DEVELOPMENT OF FRAMEWORK FOR IMPLEMENTING SUSTAINABILITY IN
BRIDGE PROJECTS WITH GREENHOUSE GAS (GHG) EMISSIONS CALCULATION
GUIDELINES BASED ON LCA METHODOLOGY IMPLEMENTATIONS
By
Sanjog Kumar Gangwal

A THESIS
Submitted to
Michigan State University
In partial fulfillment of the requirements
for the degree of
MASTER OF SCIENCE
Construction Management
2013

ABSTRACT
DEVELOPMENT OF FRAMEWORK FOR IMPLEMENTING SUSTAINABILITY IN
BRIDGE PROJECTS WITH GREENHOUSE GAS (GHG) EMISSIONS CALCULATION
GUIDELINES BASED ON LCA METHODOLOGY IMPLEMENTATIONS
By
Sanjog Kumar Gangwal
A bridge constitutes a large investment of capital, materials, and energy and is associated with
significant social, economic, and environmental impacts. Application of sustainable practices for
bridge design, construction, and maintenance can enable an environmentally responsible and
effective use of resources for this large investment. The focus of this study is to develop a
framework that will assist transportation engineers and managers in developing more sustainable
design and construction processes for new bridges, and sustainable maintenance practices for
existing bridges. This framework consists of a green rating system, which is divided into three
categories, which are design, construction, and maintenance. The last two sections are further
divided into various criteria. For each criterion the description, intent, and requirements have
been established. The requirements are established based on various industry standards such as
the Environmental Protection Agency (EPA), American Association of State Highway and
Transportation Officials (AASHTO), Federal Highway Administration (FHWA), LEED®, and
current bridge engineering standards. The certification levels for the rating system are
established based on research panel discussion and interview with MDOT experts to categorize
sustainable bridges. A bridge can be categorized as Non-Green, Certified, Green, Total Green,
and Evergreen, depending on the total score obtained by the bridge project. Lastly, guidelines
were developed to estimate GHG emissions in bridge projects based on LCA methodology to
evaluate the framework.

ACKNOWLDGEMENTS

First of all, I would like to thank GOD and my family whose blessings and support has enabled
me to read and write and anything would not have been possible without their blessings and
support. It is with immense gratitude that I acknowledge the help and support of my advisor, Dr.
Armagan Korkmaz, who has the attitude and substance of a genius: he continually had
convincingly conveyed a spirit of adventure and excitement in regard to research and without his
guidance and persistent help, this thesis would not have been possible. I cannot find my words to
express my gratitude to my committee members, Dr. Matt Syal and Dr. Sinem Korkmaz and, Dr.
Ronald S. Harichandran whose constant help and support enabled me to develop understanding
of the subject and without them this thesis would not have been possible. At last, I want to thank
my colleagues, writing center of Michigan State University and School of Planning, Design and
Construction for their support.

iii

TABLE OF CONTENTS

LIST OF TABLES………………………………………………………………………………..vi
LIST OF FIGURES……………………………………………………………………………..viii
CHAPTER 1
INTRODUCTION...........................................................................................................................1
1.1 Overview……………………………………………………………………………………1
1.2 Need Statement…………………………………………………………………………......3
1.3 Research Goal and Objectives…………………………………………………......….........5
1.3.1 Objective 1………………...………………………………………………...…….....5
1.3.2 Objective 2……………………………………………………………….…...……...6
1.3.3 Objective 3……………………………………………………………….…………..7
1.4 Research Methodology……………………………………………………………………..8
1.5 Deliverables and Research Contribution………………………………………………….10
1.6 Summary…………………………………………...……………………………………...10
CHAPTER 2
LITERATURE REVIEW ............................................................................................................. 12
2.1 Literature Review Categories ............................................................................................. 12
2.2 Sustainability Overview…………………………………………………………………...13
2.3 Current Sustainable Practices..........................................................................….………...15
2.3.1 Sustainable Design .................................................................................................... 15
2.3.2 Sustainable Construction ........................................................................................... 20
2.3.3 Sustainable Bridge Maintenance ............................................................................... 22
2.4 Existing Major Green Rating Systems…………………………………………………….24
2.4.1 LEED (2009)-New Construction............................................................................... 24
2.4.2 EnvisionTM Rating System by Institute of Sustainable Infrastructures ..................... 26
2.4.3 GreenLITES Project Design Certification Program by NYSDOT ........................... 27
2.4.4 Sustainable Highways Self-Evaluation Tool ............................................................. 28
2.5 Current MDOT practices in Bridge Design, Construction and Maintenance……………..29
2.5.1 MDOT Design Practices ........................................................................................... 30
2.5.2 MDOT Construction Practices .................................................................................. 30
2.5.3 MDOT Bridge Maintenance Practices ...................................................................... 31
2.6 Life Cycle Assessment (LCA) Applications………………………………………………32
2.6.1 Background of LCA Applications ............................................................................. 32
2.6.2 Bridge LCA ............................................................................................................... 33
2.6.3 Available LCA Tools ................................................................................................ 37

iv

CHAPTER 3
FRAMEWORK FOR ASSESSING SUSTAINABILITY IN BRIDGE DESIGN
CONSTRUCTION AND MAINTENANCE……………………………………………............39
3.1 Definition of the Framework……………………………………………………………...39
3.2 Green Rating System for the Bridges……………..……………………………………....48
3.2.1 Category 1-Design………………………………………………………………….49
3.2.2 Category 2-Construction…………………………………………………………....49
3.2.3 Category 3-Maintenance ........................................................................................... 62
3.3 Quantifying the Green Rating System…………………………………………………….79
3.4 Certification Levels………………………………………………………………………..81
CHAPTER 4
GHG EMISSIONS CALCULATION GUIDELINES BASED ON LCA METHODOLOGY….86
4.1 Introduction………………………………………………….…………………………….86
4.2 Goals and Objectives……………………………………………………………………...87
4.3 Building Blocks for Developing GHG Emissions Calculation Guidelines…………….....88
4.4 GHG Emissions Calculation Guidelines…………………………………………………111
4.5 Case Study……………………………………………………………………………….125
4.5.1 Overview ................................................................................................................. 125
4.5.2 Structure Description ............................................................................................... 125
4.5.3 Design Alternatives ................................................................................................. 126
4.5.4 Methodology ........................................................................................................... 127
4.5.5 GHG Emissions Calculation ................................................................................... 127
4.5.6 Results ..................................................................................................................... 129
4.6 LCA Matrix for the Framework………………………………………………………….129
CHAPTER 5
RESULTS/CONCLUSIONS/LIMITATIONS AND RECOMMENDATIONS FOR FUTURE
WORK………………………………………………………………………………………….133
5.1 Results and Conclusions…………………………………………………………………133
5.2 Research Limitations.........................................................................................................134
5.3 Recommendations for the Future Work………………………………………………....134
BIBLIOGRAPHY……………….………………………………………………………….......137

v

LIST OF TABLES

Table 2.1: Embodied Energy and CO2 Levels for Steel………………………………………....17
Table 2.2: LEED V.3 Certification Levels………………………………………………………25
Table 2.3: Comparison of Environmental Impacts of Two Types of Cement………………..…37
Table 2.4: GHG Impact Tools………………………………………….………………………..38
Table 3.1: Criteria Table………………………………………….……………………………...40
Table 3.2: Scoring Criteria for Accelerated bridge Construction Techniques…………………..51
Table 3.3: Scoring Criteria for Water Use Reduction…………………………………………...55
Table 3.4: Scoring Criteria for Construction Waste Management………………………………59
Table 3.5: Example Calculations for Construction Waste Management………………………...59
Table 3.6: Scoring Criteria for Bridge Deck Joints and Seals…………………………………...76
Table 3.7: Scorecard for the Green Rating System……………………………………………...79
Table 3.8: Certification Levels Determination…………………………………………………..82
Table 3.9: Certification Levels for Bridge Green Rating System……………………………….85
Table 4.1: Emission Factors Obtained Using SimaPro…………………………………………110
Table 4.2: Material Estimator…………………………………………………………………..113
Table 4.3: Case Study-Bridge Structure Details………………………………………………..126
Table 4.6: Case Study-Design Alternatives…………………………………………………….126
Table 4.7: Case Study: GHG Emission from Materials…………………………………….…..127
Table 4.8: Case Study: GHG Emissions from Transportation…………………………….……128
Table 4.9: Case Study: GHG Emissions from Transportation………………………………….128
Table 4.10: Case Study: GHG Emissions from Diversion…………….……………………….129

vi

Table 4.11: LCA Matrix Legend………………………………………….……………………130

vii

LIST OF FIGURES

Figure 1.1: Total 2002 GHG Emissions By Sector (MMT CO2 Eq.), Factoring in Purchased
Electricity………………………………………….………………………………….8
Figure 1.2: Research Methodology………………………………………….…………………....9
Figure 1.3: Steps in the Research Study………………………………………….……………...11
Figure 2.1: Categories of Literature Review………………………………………….…………12
Figure 4.1: Building Blocks for GHG Emission Calculation Guidelines………………………..89
Figure 4.2: SimaPro Organization………………………………………….……………………97
Figure 4.3: LCI Phase………………………………………….……………………………….100
Figure 4.4: Impact Assessment Phase………………………………………….………………101
Figure 4.5: Impact Assessment Phase………………………………………….………………102
Figure 4.6: Cradle to Gate Analysis of 1-Ton Portland Cement ……………………………….103
Figure 4.7: Cradle to Gate Analysis of 1-Ton Blast Furnace Slag Cement…………………….104
Figure 4.8: Cradle to Gate Analysis of 1-Ton Concrete Block…………………………………105
Figure 4.9: Cradle to Gate Analysis of 1-Ton Sand-Lime Brick……………………………….106
Figure 4.10: Cradle to Gate Analysis of 1–Ton Polypropylene Fibers…………………………107
Figure 4.11: Cradle to Gate Analysis of 1-Ton Light Clay Brick……………………………...108
Figure 4.12: Cradle to Gate Analysis of 1-Ton Latex………………………………………….109
Figure 4.13: Cradle to Gate Analysis of 1-Ton Plastic Materials and Resins………………….110
Figure 4.14: Design-Sites Category LCA Matrix………………………………………………130
Figure 4.15: Design-Materials Category LCA Matrix………………………………………….131
Figure 4.16: Design-Other Category LCA Matrix…………………………………………. …..131
Figure 4.17: Construction Category LCA Matrix…………………………………………..…..132

viii

Figure 4.18: Maintenance Category LCA Matrix………………………………………………132

ix

CHAPTER 1
INTRODUCTION

1.1 Overview
Sustainable practices are a key component in almost every aspect of our lives; green strategies
are now being incorporated in everything from foods to building cars and building engineering
structures (Louis, 2010). The U.S. transportation system involves a substantial investment on
behalf of the government and taxpayers, and widespread concern is growing over the critical
state of infrastructure (Mistry, 2005). A bridge constitutes a large investment of capital,
materials, and energy and is thus associated with significant environmental impact. In addition to
design and construction, bridge maintenance is an important issue in the United States.
Sustainability is a long-term approach that can enable environmental protection and process
improvements (EPA, 2012). Thus application of sustainable practices for bridge design,
construction, and maintenance can enable an environmentally responsible construction and
effective use of resources for this large investment.

Many Department of Transportation (DOT) bridge designers and constructors have explained
various environmental sustainable alternatives (ASBI 2007, Hong et. al., 2006). The U.S.
department of transportation states: “DOT is committed to become leader in sustainability. The
U.S. department of transportation incorporating sustainable practices in department’s mission
helps to promote energy and natural resource conservation, decrease Greenhouse Gas (GHG)
emissions, reduces pollution and contamination releases, enhances the workplace by minimizing

1

hazardous materials and chemicals and strengthens the national interest by encouraging energy
independence” (USDOT, 2011).

In recent years, DOTs have made a great effort to implement sustainable applications in bridge
design, construction, and maintenance in order to achieve their goals in an environmentallyresponsible and cost-effective manner. The Oregon Department of Transportation is a leader in
sustainability planning and initiatives and has a sustainability program focused on health and
safety, social responsibility, environmental stewardship, land use and infrastructure, energy/fuel
use and climate change, material resource flow, and economic health (ODOT, 2012).

Similarly, other DOTs like MDOT, Texas DOT, and New York DOT, have taken step in
implementing sustainability practices in design, construction, and maintenance of highways and
bridges. These DOTs are implementing sustainability practices either through the application of
sustainable materials or using green rating systems. MDOT has recently expressed their interest
in developing a framework that can be used to categorize sustainable bridges, involving the
application of sustainable materials, standards that aim at reducing environmental pollution, and
other concepts that contribute towards sustainability.

Feedback in this study is taken from MDOT and the framework is developed based on MDOT
requirements, therefore, this study mostly relates to the bridges in Michigan. This framework can
assist MDOT in implementing sustainable approaches in bridge projects. However, these
concepts can also be used as a guideline for other transportation agencies by modifying the

2

framework or requirements of some of the criteria used to meet their own local conditions and
needs.

Chapter 1, “Introduction” discusses importance of sustainability, research goal and objectives
used to accomplish the goal. The research methodology used is also shown. Chapter 2,
“Literature Review” compiles all the current sustainable practices followed in building
construction projects, bridge projects and other sectors. Literature was reviewed related to
sustainable theoretical practices, existing green rating systems in United States and LCA
applications to compute GHG emissions in construction projects. Chapter 3, “Framework for
Assessing Sustainability in Bridge Design, Construction and Maintenance” includes the
development of framework for to implement sustainability in bridge projects. This includes
development of green rating system for the bridges, quantifying green rating system, determining
certification levels for the green rating system to categorize sustainable bridges. Chapter 4,
“GHG Emission Calculation Guidelines Based on LCA Methodology” to evaluate the
framework and support sustainable decision-making. This includes the development of excel
based tool, which can be used to compute estimated GHG emissions due to materials and
equipment that can be used in bridge projects. Chapter 5, “Results and Conclusions” discuss the
summary of results and provides recommendations for future work.

1.2 Need Statement
The built environment has great impact on the natural environment, human health, and economy
(EPA, 2010). Incorporating green strategies has seen a large number of environmental,
economic, and social benefits. The EPA lists the potential benefits of green buildings, which

3

include enhancement and protection of biodiversity and ecosystems, improving air and water
quality, reducing waste streams, conserving and restoring natural resources, reducing operating
costs, minimizing strain on infrastructures and improving overall quality of life (EPA, 2010).
Despite billions of dollars in federal, state, and local funds directed toward the maintenance of
existing bridges, 69,223 bridges, i.e., 11.5% of total highway bridges in the U.S., are classified as
"structurally deficient," requiring significant maintenance, rehabilitation, or replacement (Shoup
et. al., 2011). More than 13% (more than 1400) of Michigan bridges are considered structurally
deficient under the federal rating system and thus need significant repairs. Approximately 11,000
bridges in Michigan are about 41 years old and approaching their 50-year life (Helms, 2011).

Since many of these bridges are approaching their maximum service life, they need to be
replaced. All the activities, such as the construction of new bridges, repair, rehabilitation, and
replacement of the existing bridges are associated with considerable environmental impact.
Therefore, sustainable applications that can reduce environmental impact need to be developed
and implemented.

Activities involved in construction have a significant environmental footprint, especially in terms
of greenhouse gas (GHG) emissions and energy consumption (Orabi et. al, 2012). The
Environmental Protection Agency (EPA) ranks the construction industry third in generation of
GHG emissions with 6% of all industry related emissions in the United States (EPA, 2009).
Transportation is a vital part of the economy but also a significant source of GHG emissions. It
involves large number of construction activities, which directly or indirectly release greenhouse
gases, water, and land pollutants. Several studies have focused on measuring the environmental

4

impacts of construction activities and finding ways to minimize these impacts. There has been
recent need to adopt methodologies that aim at reducing such impacts and contribute to
sustainability. Therefore, this study is necessary for developing a framework for bridges that can
be used as a guideline to achieve sustainability.

1.3 Research Goal and Objectives
The overall research goal is to develop a framework, which can be used as a guideline to achieve
environmental sustainability in bridge projects and enable various transportation agencies and
organizations to be leading states for the green design, construction, and maintenance of bridges.
The goal was achieved by meeting the following objectives:
1. Summarize the current sustainable practices followed in building projects, bridge projects
and other sectors.
2. Develop a framework that can be used to implement sustainability in bridges. This will
include the development of a green rating system for bridges and determination of
certification levels to categorize sustainable bridges.
3. Develop GHG emissions calculation guidelines for bridges based on LCA methodology to
determine the carbon footprint associated with various items in bridge construction projects
that can enable transportation agencies that can be used to evaluate the framework and
investigate various strategies to reduce GHG emissions, thus supporting sustainable decisionmaking.
1.3.1 Objective 1
Summarize the current sustainable practices followed in building projects, bridge projects
and other sectors.

5

To achieve this objective, a theoretical analysis of journals, articles, research papers, and theses
was done. In this objective, literature is reviewed related to sustainable practices followed in
building construction and infrastructure. Various green rating systems such as LEED V.3 by
USGBC, Envision Rating System by Institute of Sustainable Infrastructure (ISI), INVEST rating
system developed by FHWA etc. were reviewed. Sustainable practices followed by various U.S.
transportation agencies were also studied in detail. Application of sustainable materials in bridge
design, construction, and maintenance and LCA applications were studied and construction
standards described by EPA, AASHTO, and FHWA etc., were reviewed to establish
requirements in the framework, which is described in detail in Chapter 3.

1.3.2 Objective 2
Develop a framework that can be used to implement sustainability in bridges. This will
include the development of a green rating system for bridges and determination of
certification levels to categorize sustainable bridges.
Based on the detailed content analysis discussed in the Objective 1, the framework consisting of
a rating system was developed. The rating is divided into three categories as follows: 1) Design,
2) Construction, and 3) Maintenance. The details of the design category can be found in MS
thesis “Life Cycle Cost Analysis and Delphi Survey to Assist Sustainable Bridge Design,
Construction and Maintenance” developed by Awan (2012), which is based on MDOT research
project work titled as “Implementation of Sustainability in Bridge Design, Construction and
Maintenance”. The description, intent, requirements, and standards have been established for
each criterion under Construction and Maintenance category by consulting various references
such as the American Association of State Highway and Transportation Officials (AASHTO),

6

American Standard for Testing Materials (ASTM), Environmental Protection Agency (EPA),
Leadership in Energy and Environmental Design (LEED®V.3) construction standards. In order to
quantify the rating system, point values are assigned to each criterion and weights are assigned to
all three categories. The weights are assigned based on the results of the Delphi survey
conducted at MDOT divisions, which were taken from thesis “Life Cycle Cost Analysis and
Delphi Survey to Assist Sustainable Bridge Design, Construction and Maintenance (Awan,
2012). The certification levels were developed based on research panel discussion and interviews
with MDOT experts to categorize sustainable bridges. The methodology is described in detail in
the relevant section.

1.3.3 Objective 3
Develop GHG emissions calculation guidelines for bridges based on LCA methodology to
determine the carbon footprint associated with various items in bridge construction projects
that can enable transportation agencies that can be used to evaluate the framework and
investigate various strategies to reduce GHG emissions, thus supporting sustainable
decision-making.
Transportation sector is the second biggest contributor of GHG emissions followed by the
industrial sector, which is the biggest contributor of GHG emissions. In 2002, it is estimated that
transportation sectors is responsible for 1908 MMT CO2 Eq., which is 29% of all the key sectors
(EPA, 2008). Figure 1.1 shows estimates of GHG emissions from various sectors in United
States.

7

GHG Emissions
1%
9%
29%

Industrial
Transportation

17%

Commercial
Residential
Agriculture
17%

U.S. Territories
27%

Figure 1.1: Total 2002 GHG Emissions By Sector (MMT CO2 Eq.), Factoring in Purchased
:
Electricity (Source: EPA, Inventory of U.S. Greenhouse Gas Emissions and Sinks) (For
Greenhouse
interpretation of the references to color in this and all other figures, the reader is referred to the
electronic version of this thesis)
The guidelines include developed of excel based tool that can be used to compute GHG
emissions from materials and equipment that can be used in bridge construction projects. GHG
emission calculation can be used to evaluate the framework.

1.4 Research Methodology
A research methodology shown in Figure 1.2 has been developed that lists the steps in the
process to accomplish the goal. First, literature was reviewed related to current sustainable
practices followed in building construction, bridge construction and other sectors. Then it was
sectors
determined that which of those practices can also be used in the bridge construction projects.
Based on content analysis or the literature review, an overall framework including a green rating

8

system for bridges is developed. Feedback on the rating system is taken regularly by MDOT
until they suggest no further modifications. After the framework is approved by MDOT, the
rating system is quantified using the results of the Delphi survey conducted at MDOT divisions.
At last, GHG emissions calculation guidelines were developed to support the sustainability of
bridge projects.

Summarize the current sustainable
practices followed in building projects,
bridge projects and other sectors.

Overall Framework
System for Bridges)

If further
modification
suggested by
MDOT

(Green

Take feedback on the
framework for MDOT

Develop GHG emission
calculation guidelines

Figure 1.2: Research Methodology

9

Rating

If no further
modification
suggested by
MDOT

Quantify the
green rating
system

1.5 Deliverables and Research Contribution
This research aims to provide a framework to organizations to implement green practices in
bridge design, construction, and maintenance. This will be used to categorize sustainable bridges
and contribute to sustainable environment. These outputs were provided in the following
chapters and the relevant appendix.

1.6 Summary
As discussed in Chapter 1, sustainable construction is a key component in sustainable
development. Any bridge project should be executed in such a way that sustainability is
incorporated in every stage including design, construction, and maintenance. Sustainability is
about balancing what is beneficial to people, while considering what is economically sound and
environmentally compatible. Implementing sustainable approaches may increase the project cost,
however it may be warranted when all external cost are considered (NYSDOT, 2008). Climate
change, energy use, environmental impacts, and limits to financial resources for transportation
infrastructure are major global concerns. It requires new approaches to planning, designing,
constructing, operating, and maintaining transportation solutions and systems (AASHTO, 2009).
There are various practices followed at design, construction, operation, and maintenance levels.
Many DOTs excel in certain and are concerned with the sustainability triple bottom line as well
as the implications for mitigation and adaptation to climate change (AASHTO, 2009). The focus
of this research study is to develop a framework that will assist transportation engineers and
managers develop more environmentally sustainable design and construction processes for new
bridges, and sustainable maintenance practices for existing bridges. Figure 1.3 shows the steps in
the research study, which include the development of a green rating system for the bridges,

10

quantifying the green rating system, developing GHG emission calculation guidelines, and
recommendations for the future work.

Development of Green Rating System for
Bridges

Quantification of Green Rating System
Using Delphi Survey Method

Sustainable Framework
for Bridge Design,
Construction and
Maintenance

GHG Emission Calculation Guidelines
and Life Cycle Cost Analysis

Recommendations for the Future Work

Figure 1.3: Steps in the Research Study

11

CHAPTER 2
LITERATURE REVIEW

2.1 Literature Review Categories
In this chapter, literature is reviewed to form three categories as shown in Figure 2.1. The first
erature
category reviews literature about current sustainable practices in bridge design, construction and
maintenance by consulting articles, theses, books, journals and magazines. The second category
reviews literature about major existing Green Rating Systems in United States such as LEED V.3
re
(USGBC, 2009); EnvisionTM Rating System (ISI, 2012), GreenLITES Certification System
(NYSDOT, 2008), Sustainable Self
,
Self-Highway Evaluation Tool (FHWA, 2012). Other green
2012)
rating system for bridges developed by Lauren R. Hunt was also reviewed. The third category
g
focuses and summarizes the existing literature related to LCA applications. It includes the
concept of LCA, its applications, use of LCA software and estimating GHG emis
emissions.

Current Sustainable
Practices

Sustainable Design

Sustainable
Construction

Sustainable
Maintenance

Major Existing Green
Rating Systems in U.S.

LCA Applications

LEED V.3 (USGBC)

LCA Concepts

Envision Rating
System (ISI)
LCA Tools
GreenLITES Rating
System (NYSDOT)
Sustainable Highway
Self Evaluation Tool
(FHWA)

Figure 2.1: Categories of Literature Review
12

GHG Emission
Calculations

2.2 Sustainability Overview
Sustainable development is defined as “development that meets the needs of the present without
compromising the ability of future generations to meet their own need” (WCED, 1987). Since,
buildings in US contribute 39% of all carbon dioxide (CO2) emissions and 40% of raw material
use, 72% of the total electricity consumption, (EPA, 2009); sustainability is increasingly adopted
by the US building industry with the motivation to reduce the environmental impacts. Several
tools have been developed to serve the building industry for sustainable design and construction:
green building rating systems such as the U.S. Green Building Council’s (USGBC, 2009)
Leadership in Energy and Environmental Design (LEED®), life cycle cost analysis (LCCA), and
life cycle assessment (LCA). These tools can also be applied to bridge design, construction and
maintenance to make new and existing structures more environment friendly in the long run, in
other words more sustainable.

In the United States, sustainability assessment systems are mostly available for buildings and
there is lack of guiding and/or measuring sustainability practices for bridges (Whittemore, 2010).
United States Green Building Council (USGBC) is a non-profit organization dedicated to
sustainable building design and construction. USGBC’s Leadership in Energy and
Environmental Design (LEED®) is a rating system, used as a national standard for the design,
construction and operation of sustainable or green buildings. From 2005 to 2008, green building
construction increased dramatically from 2% to 20% of overall construction (McGraw Hill
Construction, 2012). Although, LEED® rating system is only used for buildings but some useful
metrics are also applicable to bridge sustainability assessment (Whittemore, 2010).

13

A sustainable bridge can be defined as the one that is “conceived, designed, constructed and
maintained, and eventually put out of service in such a fashion that these activities demand as
little as possible from the natural, material and energy resources from the surrounding
community” (Whittemore, 2010).

Sustainability can be explained under 1) Structural Sustainability and 2) Environmental
Sustainability in the context of bridges. The structural sustainability, in American Concrete
Institution (ACI) fall 2010 Convention, states "A structural sustainable concrete bridge should
provide an overall life of 100 to 150 years"; “They should have minimum of shrinkage (plastic,
drying, chemical shrinkage) and cracking". For example use High Performance Concrete (HPC)
to minimize dry shrinkage use saturated lightweight aggregates for internal curing for the
promotion of hydration to minimize shrinkage and cracking. HPC should have other optimum
concrete characteristics such as low water/cement ratio, high flexural strength. “Long service life
of bridge decks over 100 years can be achieved with low shrinkage, low permeability HPC,
compared to only 20 years for normal strength concrete decks.” (ACI, 2010). Although structural
sustainability is important, the focus will be on environmental sustainability of the bridges.
Environmental sustainability deals with the environmental impacts of the products or the process
in all life cycle stages of the bridge, i.e. to measure the environmental impacts and performance
of the products or process over the design, construction, use, maintenance and, disposal stages
(EPA, 2006). The following sections expand on the environmental aspect of sustainability for
bridges.

14

2.3 Current Sustainable Practices
A number of articles, theses, journals, books and magazines were consulted to review current
sustainable approaches in bridge design, construction and maintenance. This section describes
methodologies and approaches used to assess sustainability. The current sustainable practices are
reviewed in three categories, which are a) Sustainable Bridge Design, b) Sustainable Bridge
Construction and, c) Sustainable Bridge Maintenance.

2.3.1 Sustainable Design
Design of the bridges is an important phase where most of the decision taken can have impacts
on later stages. Incorporating sustainability approaches and methods in the design stage is
important for achieving sustainability. For example site selection, material selection for design,
service life design, span arrangement, substructure type, geometry, foundation types are some of
the factors that should be taken into consideration during the design stage and alternative ways
are usually considered to achieve sustainability.

Lounis & Daigle (2007) compared the environmental benefits of High Performance Concrete
Decks (HPC) and Normal Performance Concrete (NPC) bridge decks. It was found that
construction of HPC structures results in reduction in the number of maintenance and repair
actions that will result in a reduction in both materials and energy consumption as well as in a
reduction of CO2 emissions and waste production. A simplified life cycle environmental analysis
of the two bridge decks was undertaken by focusing on two impacts: a) emissions of CO2; and b)
waste production (or landfill use). In terms of environmental impact, it is estimated that the HPC
deck alternative yields a reduction of 65% in the CO2 emissions compared to the normal
15

concrete deck. It was also found that based on the onset of corrosion as the end of service life
criterion, the HPC deck alternative incorporating SCMs has a service life that can vary from 3 to
10 times the service life of normal concrete deck having the same water-to-cementitious
materials ratio (Lounis & Daigle, 2007).

High service life design requires the designer to explore outside the current codes, evaluate
environmental loading and establish material performance over a long period, requiring
extrapolation of current knowledge of climate and material properties as well as the extrapolation
of material deterioration models (Connal, 2009).

Sustainability objectives for bridges can also be best accomplished by ensuring durable bridges
with long service life and low maintenance inputs that, on a whole-of-life basis, minimize
material consumption over the long term. It is likely that such a bridge also has the lowest wholeof-life economic cost (Connal, 2009).

There is need for concrete durability design. Reinforced concrete and pre-stressed concrete
bridges, which are exposed to aggressive environments, are affected by the corrosion of steel due
to ingression of chlorides and due to carbonation. Chloride ingression has been formulated on the
assumption that it would occur by ionic diffusion. Based on it concrete mix, cementitious content
were determined and the additional materials such as fly ash and slag has been used to reduce the
heat of hydration and greenhouse gas emission thereby increasing the durability.

Another factor, which decreases the durability of the structure, is carbonation. The primary
concern is for superstructure elements. It decreases the PH value of concrete due to which the
16

passive iron oxide layer, which protects reinforcement from corrosion, is not maintained.
Therefore it is important to reduce the effect of carbonation, which can be reduced by using high
quality concrete and sufficient depth of cover. To achieve long life of a bridge, selection of good
quality of concrete; selection of greater cover to reinforcement; provision of electrical continuity
for reinforcement in substructure element and; Good detailing to enable compaction of concrete,
along with good vibration and subsequent curing during construction, to ensure a dense layer of
cover concrete are considered important factors (Connal, 2009).

Materials play an important role in sustainability and number of research studies has been
conducted to determine sustainable properties of materials. Steel bridges offer numerous
advantages contributing to sustainability. Offsite production in fabrication plants results in
minimum waste. Use of automated production, using robotic welders’ results in safe
environment. A single clear span for the bridge is one of the best environmental solutions,
avoiding permanent piers in the river. Steel is recyclable material and it can be recycled and
reused multiple numbers of times without affecting its structure or properties. It promotes
management of sustainable resources. It minimizes the effect on local community, as steel
components are manufactured offsite. Selection of steel ensures reduced energy consumption and
CO2 level emissions as shown in Table 2.1.
Table 2.1: Embodied Energy and CO2 Levels for Steel (BCSA & Corus, 2009)
Steel Sections

Steel Plate

Embodied CO2

0.762 tCO2/t

0.919 tCO2/t

Embodied Energy

0.762 tCO2/t

0.919 tCO2/t

17

Use of weathering steel minimizes the need for future maintenance and any associated road
closures (BCSA;Corus, 2009). Weathering steels are high strength, low alloy steels that can
provide greater protection to corrosion. Since copper is used as an alloy, it provides a
mechanism, which provides prevention from atmospheric corrosion. FHWA is emphasizing on
using weathering steel for bridge construction as it improves the performance and research and
studies are underway of weathering steel bridge performance in macro and microenvironments.
(Kozy & Triandafilou, 2011).

TxDOT has built over 100 weathering steel bridges since 1970. A research study was conducted
for TxDOT, which includes field visits where different samples where collected to examine the
presence of protective oxide film, section loss, and presence of chlorides, cause and control of
staining, and any other apparent corrosion and aesthetic performance issues. And it was found
that uncoated weathering steel is a very good material for TxDOT bridges as it provides a good
protective oxide film forms, protecting the steel from further corrosion (McDad et. al., 2000).

GRP decks have great significance in sustainability of bridges. It is a composite steel hybrid
structure, which has requires minimal maintenance and is much economical. In the longer term,
road users should benefit from reduced delay and disruption, since the bridge will need minimal
maintenance. Fast installation with less disruption to traffic, and reduced long-term maintenance
are two compelling reasons for the selection of a composite bridge deck over concrete. GRP
offers several advantages over conventional bridge materials such as reinforced concrete,
including: higher strength to weight ratio; high degree of pre-fabrication possible; faster
installation; and corrosion resistance (Jacob, 2008).

18

Transportation industry uses alternative materials in the construction of pavements as they are
currently using bulk materials such as natural and fine aggregates. Materials including industrial
by-products, concrete aggregates, old asphalt pavement, scrap tires, fly ash, steel slag, and
plastics are often used as alternate materials for natural aggregates. These materials are best used
for their environmental suitability, recyclability and sustainability in concrete and road pavement
applications, as well as their environmental impact on surface and ground waters. Many types of
products result in the creation of large quantities of solid waste materials (SWMs). Many of these
SWMs remain in the environment for long periods of time and cause waste disposal problems.
Existing landfills are reaching maximum capacity and new regulations have made the
establishment of new landfills difficult. Disposal cost continues to increase while the number of
accepted wastes at landfills continues to decrease. Use of use of industrial by-products in the
construction of transportation networks can contribute to sustainable development (Kassim et. al.
2008).

Currently, industrial by-products (such as fly ash, steel slag, plastics, and scrap tires) are used as
substitutes for natural aggregates in road construction. Various solid wastes that have been used
in several highway applications for sustainability considerations are bag-house fines, blast
furnace slag, carpet fiber dusts, coal bottom ash/boiler slag, coal fly ash, contaminated soils, flue
gas desulfurization scrubber material, foundry sand kiln dusts, mineral processing wastes,
municipal solid waste incinerator ash (Kassim et. al. 2008).

Other practices that are considered to contribute to sustainable design are longer spans, high
strength, more durability-better long term performance, and smaller cross-sectional area; use of

19

high performance composites: fiber reinforced polymers (FRP), FRP wraps used for
rehabilitation projects; use of aluminum as light weight bridge decks results in 80% lighter deck
than concrete and is more corrosion resistant, requires fewer welds than steel thus reducing
potential failure points; use of high performance steel, for example a new grade of steel: hps485w which results in increased toughness, superior weldability and high corrosion resistance;
using hybrid designs results in 17% weight savings, 11% cost savings (Gilbertson, 2008).

2.3.2 Sustainable Construction
There are two main processes during construction stage, which are responsible for energy
consumption and emissions. These are a) Transportation and b) Operation. In a normal life cycle,
main transportation operations occur ‘‘to site’’, ‘‘from site’’ and “on site”. For the evaluation of
energy releases during transportation, average distance travelled and fuel efficiency of the
vehicles which travels to and from the site are considered (Pacheo & Campos, 2010). Energy
consumption during construction operations is an important factor that should be considered.
Energy consumption is found considering the weight of equipment, energy it consumes per hour
of operation and the duration of a construction of a typical bridge deck (Pacheo & Campos,
2010).

Different road equipment such as trucks and other vehicles are used during construction
operations to transport materials to and from site, which consumes fuel and release wastes to
atmosphere. Non-efficient fuel vehicles can increase fuel consumption and also releases GHG
emissions. Similarly, various non-road construction equipment such as excavators, bulldozers,
compactors, pressure washers, cement and mortar mixers, pumps, trenchers, rollers and other

20

construction equipment used during operation consumes fuel and releases energy. Air emissions
from construction equipment contribute significantly to the degradation of the environment.
Therefore, it is imperative to use such type of equipment, which produces lesser emissions than
conventional ones. “Non-road engines are all internal combustion engines except motor vehicle
(highway) engines, stationary engines (or engines that remain at one location for more than 12
months), engines used solely for competition, or engines used in aircraft. The non-road standards
cover mobile non-road diesel engines of all sizes used in a wide range of construction,
agricultural and industrial equipment” (EPA, 2004). So, Non-road equipment is used in
construction and not on roads like cars, buses etc.

EPA recommends non-road construction equipment to “have engines that meet the current U.S.
Environmental Protection Agency (EPA) Tier emission standards (Tier 3/Interim Tier 4 as of
April 2011) in effect for non-road engines of the applicable engine power group and; “have
diesel retrofit devices for after-treatment pollution control verified by EPA or the California Air
Resources Board (CARB) for use with non-road engines” (FHWA, 2012). Using alternative
fuels such as biofuels and material recycling have been considered as green practices.

Reducing fuel use can be an effective step in reducing GHG emissions. Diesel contributes to
22.37 lbs of CO2/gallon and Gasoline contributes to 19.54 lbs. of CO2/gallon. Similarly Propane
and Natural Gas contributes to 12.66 lbs. CO2/gallon and 11.7 lbs. CO2/1000 cu.ft. These show
that significant amount of CO2 emissions are associated with fuel use. LCA helps in determining
the total emissions and could provide support in investigating various strategies to reduce these

21

emissions. If ways are implemented to reduce fuel use by 3%, 2.02 MMT of CO2 emissions will
be reduced. Using biofuels for trucks and non-road equipment can reduce significant GHG
emissions (EPA, 2009).

Accelerated bridge construction technique is an innovative approach greatly contributing towards
sustainability. Accelerated construction is used to achieve the construction of structures in a
shortest possible time while decreasing delays and traffic disruption. It is not just building
structures rapidly but also entails a variety of techniques, processes, and technologies to achieve
the desired result of reducing congestion due to construction while improving quality. These
techniques are used for the construction of new bridges and also the replacement of existing
bridges (Ralls, 2007). Using precast bent caps, precast columns, precast deck panels, precast
barriers, prefabricated trusses, precast abutments, retaining walls and footings allows
manufacturing to take place in a controlled environment thereby reducing impacts to traffic and
reducing environmental impacts. The main reason for using such techniques is to reduce on-site
construction time and mobility impact time (FHWA, 2012).

2.3.3 Sustainable Bridge Maintenance
Bridge maintenance is major part of a bridge life cycle. There are number of activities involved
in bridge maintenance which may have significant impacts on environment. Bridge maintenance
usually includes short-term fixes, medium-term fixes and long-term fixes. Short-term fixes
include capital preventive maintenance (CPM). It applies lower-cost treatments to slow the
deterioration rate, maintain or improve the functional condition and extend the pavement's
service life. Medium term fixes includes rehabilitation. Rehabilitation is the application of

22

structural enhancements, such as multiple course resurfacing or concrete pavement repairs, that
improves the roadway or overlaying a bridge deck and superstructure repair to improve a bridge.
Long-term fixes include reconstruction/replacement. Reconstruction is the entire building of the
roadway. Replacement refers to replacement of the bridge deck, super structure replacement or
replacement of whole bridge (MDOT, 2011).

Many attempts have been made to reduce number of maintenance activities to reduce
environment impacts associated with them. Use of durable materials prolong service life of
bridge components and thus reduce future maintenance activities. High performance structural
materials and FRP can be used to design bridges for more durability thus reducing future
maintenance activities (Tang, 2004). Efficient inspection technologies should be used to properly
assess the condition of bridges timely so that proper actions can be taken regarding maintenance
actions. Use of efficient inspection technologies can ensures improved data quality while
simultaneously controlling the cost of data collection. Further development and evaluation of
improved visual inspection procedures, innovative nondestructive testing methods, and
automated methods to gather and manage data should be encouraged (Hearn et. al., 2008).
FHWA categorizes bridges as structurally deficient or functionally obsolete based on their
conditions and ratings. Bridge eligible for rehabilitation or replacement is determined by a rating
formula. This information is used by FHWA to develop National Bridge Inventory (NBI). In
order to estimate the future maintenance and repair needs, a bridge management system (BMS)
can be used. BMS provides comprehensive management of bridge system and provides
improvement in the type and quality of data is collected, stored, managed and used in a bridge

23

system analysis; realistic and reliable forecast of future needs and; a logical methods for setting
priorities for current needs (WSDOT, 2010).
The focus should be more on quantitative assessment of performance of bridge performance
rather than visual inspections and condition ratings. A variety of permanent sensors can be
installed on bridges, which can automatically detect the data with the change in chemical and
electrical properties of materials related to deterioration, aging in coatings and changes in service
environment or exposure. Sensors can report to wireless networks and data can be analyzed and
deterioration can be detected automatically by computer workstations (Hearn et. al., 2008).

2.4 Existing Major Green Rating Systems
Since the focus of this study is to develop a green rating system for the bridges, which can be
used to define and measure sustainability in bridges, various major green rating systems
currently used in the United States shown in Figure 2.2 were reviewed. These green rating
systems are developed mostly for buildings and highways. Brief overviews of the existing green
rating systems are as follow.

2.4.1 LEED (2009)-New Construction
Leadership in Energy and Environmental Design (LEED®) is a rating system for design,
construction and operation of sustainable buildings. It was developed by the USGBC in 1998.
This rating system was mainly developed to define and measure Green Buildings. So far,
USGBC has developed five versions i.e. version 1.0 in 1998, version 2.0 in 2000, version2.1 in
2002, version 2.2 in 2005 and version 3.0 in 2009. The latest, LEED® version 3.0 is currently
used for existing and new commercial, residential and institutional buildings. Since its inception

24

in 1998, USGBC has grown to encompass more than 24,662 projects in the United States and 30
countries covering over 1.627 billion square feet of development area which shows the impact
and wide recognition for LEED® in US and around the globe.

The rating system is divided into six main categories with additional points awarded for
innovation. These categories are based on energy consumption, location, environmental
principles and material used. They are: Sustainable Sites, Water Efficiency, Energy and
Atmosphere, Indoor Environmental Quality, Material and Resources, and Innovation in design.
These categories are further divided into various credits. Each credit has certain requirements,
listing strategies to fulfill those requirements. The rating system has a total of 100 base points
and four certification levels i.e., certified, silver, gold and platinum. The Figure 2.3 shows the
categories and credits of LEED® 2009. It is important to mention here that this is the most
updated version of LEED®, credit weights are calculated based on a life cycle analysis tool
(TRACI), and additional regional priority points are taken into account. There are four
certification levels are developed in LEED rating system as shown in Table 2.2.
Table 2.2: LEED V.3 Certification Levels (USGBC, 2009)
Certification Level

Score Range

Certified

40-49

Silver

50-59

Gold

60-79

Platinum

80 and above

Certain credits can be adopted from LEED® 2009 rating system to develop the rating system for
bridges. The factors considered in analyzing the sustainability of buildings are materials, water,

25

energy, location and indoor air quality while the critical factors that apply to bridges are location,
materials, water and traffic impacts. Whittemore (2010) explained the equivalent goals for
sustainable bridges by comparing them with the sustainable goals for buildings. His analysis
explained the useful metrics from LEED® 2009 that can be taken to define and measure
sustainability in bridges. So, some useful metrics can be extracted to define sustainable bridges.

For instance, when crediting for water use and quality, how the hydraulic openings will affect the
upstream and downstream floodplains and what systems are in place, ensures that the
consumption of the potable water is the least and the runoff from the structure is of the highest
quality (Whittemore, 2010). Therefore, such requirements are to be established after reviewing
the standards, which ensures the optimum use of water and its quality. Likewise, certain other
credits and prerequisites from LEED® can also be adopted in the rating system for bridges. These
are Construction activity pollution prevention, Site selection, Brownfield Redevelopment, Stormwater Management-Quantity Control, Storm-water Management-Quality Control, Recycled
Content, Material Reuse, On-Site Renewable Energy, Regional Materials.

2.4.2 EnvisionTM Rating System by Institute of Sustainable Infrastructures
The institute for sustainable infrastructure (ISI) developed a new rating system to evaluate the
sustainable infrastructure projects. This rating system evaluates the sustainability for wide range
of infrastructure including bridges. ISI was formally launched in 2011 and introduced a rating
system that was developed by a working group from American Council of Engineering
Companies (ACEC), American Public Works Association (APWA) and American Society of
Civil Engineers (ASCE).

26

Envision is an objective and comprehensive framework that describes criteria, which can
influence the project elements, and processes, which can significantly influence the outcome of
the infrastructure project and its impacts on the environment. Not only has it focused on
environmental, social and economic performance, but the overall delivery of the infrastructure
project. This rating system promotes project management and business strategy for sustainable
infrastructure solutions. Envision evaluates the sustainability of a wide range of civil
infrastructure projects vital to our communities, to protecting the environment, and will award
and recognize projects that meet that goal. The system will evaluate and score existing
infrastructure and serve as a goal for new and renovating projects to achieve (ISI, 2012). The
Envision rating system is divided into 10 sections are Project pathway contribution, Project
strategy and management, Communities: long and short term effects, Land use restoration,
Landscapes, Ecology and Biodiversity, Water resources and environment, Energy and carbon,
Resource management including waste, Access and mobility. These are the ten criteria that
include 74 sub-criteria each of which is assigned point values to rate the sustainable
infrastructure.

2.4.3 GreenLITES Project Design Certification Program by NYSDOT
The New York State Department of Transportation has developed a GreenLITES (Leadership in
Transportation and Environmental Sustainability) certification program for implementing
sustainability in transportation projects. GreenLITES project design certification program
developed by NYSDOT in 2008 includes the development of a green rating system to define and
measure sustainability of highways. It shows their commitment in improving the quality of

27

transportation infrastructures by minimizing environmental impacts and reducing depletion of
resources.

The rating system is based on five categories, which are sustainable sites, water quality,
materials and resources, energy and atmosphere and innovation. It has four certification levels
i.e. certified, silver, gold and evergreen. The project rating may fall into any of the category
based on the cumulative score obtained. The cumulative score is obtained by summing points of
each criterion. It was formed after the US Green Building Council's LEED program and the
University of Washington's Greenroads program and is useful in determining sustainability in
transportation infrastructure projects. Many of the criteria are also directly applicable for the
bridges (NYSDOT, 2008). “The program is also intended to be a model for other department
sustainability initiatives, providing a benchmark to follow for incorporating greater levels of
sustainability into the department's work” (NYSDOT, 2008).

2.4.4 Sustainable Highway Self-Evaluation Tool
INVEST is a self-evaluation tool developed by FHWA is a web-based collection of criteria,
allows states to integrate sustainability in transportation projects. It is a voluntary tool and can be
used by state and various stakeholders to measure sustainability of transportation projects. This
tool can be accessed at https://www.sustainablehighways.org/All_Pilot_Criteria_11_1_2011.pdf

FHWA’s INVEST can help transportation agencies and organizations integrate sustainability
practices in transportation projects and provide practitioners to evaluate sustainability in their
transportation projects as it provides information and techniques to integrate sustainability best

28

practices. It is developed with input from state and local transportation agency officials and staff
and professional organizations such as AASHTO and ASCE. FHWA is continually updating this
tool as the transportation sustainability advances. It is divided into three main categories:
planning and process criteria, project development criteria and operations and maintenance
criteria. A total of 61 criteria are described under these categories. This rating system can also be
used as a benchmark to develop a rating system specifically for the bridges (FHWA, 2012).

2.5 Current MDOT practices in Bridge Design, Construction and Maintenance
Current MDOT applications related to bridge design, construction and maintenance were
reviewed. In addition, current MDOT practices related to sustainable applications have been
compiled. The construction of a bridge mainly involves three stages i.e. design, construction and
maintenance. These stages are all related to each other: design practices affect the construction
stage; and design and construction stages affect maintenance over the lifetime of bridge. The
design stage of the bridge commences with the selection of materials, span arrangements, girder
spacing, bearing types, substructure type and geometry, and foundation types. Design of deck
slab, interior and exterior girders, bearing, abutments, piers and foundations are the main steps in
design. The bridge design should consider construction and long-term maintenance costs
(AASHTO 2003).

All these design parameters coupled with environmental conditions such as location and site lead
to various procurement and construction applications in the next stage. In the long run
maintenance processes to keep bridges operational and safe also are affected by all the decisions
made in the design and construction stages. When considering bridge maintenance, preservation

29

techniques should also be considered. As, preservation treatments over time can reduce the
overall cost of bridge maintenance. All decisions made in the life cycle of a bridge, especially the
ones that are made early in the process, impact consequent stages. They all need to be critically
analyzed for environmental and economic effects during the life cycle of a bridge. Therefore,
examining current MDOT practices is vital in this study to determine the key decisions made in
design, construction and maintenance of the bridges. MDOT current practices were established
by studying MDOT bridge design manual, MDOT soil erosion and sedimentation control
manual, MDOT drainage manual, MDOT scoping manual, capital preventive maintenance
manual, material source guide and MDOT P/PMS task manual. These manual and guides can be
accessed at http://www.michigan.gov/mdot/0,1607,7-151-9622_11044_11367---,00.html.

2.5.1 MDOT Design Practices
The following design practices of MDOT were studied in detail:
a) General Information Site Condition: Temporary support systems and construction methods,
clear zone considerations, concrete QA/QC.
b) Preliminary design calculations: Design specifications, design methods, and design stress.
c) Design: In design practices bridge materials, span arrangements; girder spacing, bearing
types, substructure type and geometry, and foundation type were examined (MDOT, 2012).

2.5.2 MDOT Construction Practices
a) Erosion and Sedimentation Control: The primary intent is to protect the waters of the state by
minimizing erosion and controlling sediment. MDOT adopts a soil erosion and sedimentation
control program, consists of commitment to environmental stewardship responsibilities;

30

appropriate staff training; specifications and project plans that address erosion control issues
(MDOT, 2006). The development of the program is divided into three phases which planning,
design and construction phase.

b) Maintenance Activities and Projects
Since maintenance activities also have potential impacts on lakes, streams and wetlands, MDOT
also conduct soil erosion and sedimentation control measures in maintenance projects.
Appropriate SESC measures and NPDES requirements will be included when planning,
designing, and completing maintenance projects and activities involving earth disturbances,
regardless of size and location. An earth change plan is also prepared for the maintenance.

c) MDOT Storm-Water Management
MDOT has large transportation network and associated drainage system, which accumulate large
amount of contaminants. These contaminants may be washed away by the rain, snow melts and
may enter streams, rivers and lakes. Excess contaminants may cause public health concerns,
harm aquatic and animal life. MDOT developed a storm water management plan (SWMP) to
reduce or eliminate the storm water pollution. The SWMP describes procedures and practices
used throughout the planning, design, construction, operation and maintenance of the
transportation infrastructure to limit the discharge of pollutants (MDOT, 2012).

2.5.3 MDOT Bridge Maintenance Practices
MDOT uses mix of fixes strategy for the maintenance of bridges. This strategy uses combination
of long-term fixes, medium term fixes and short term fixes. Long-term fixes include

31

reconstruction/replacement. Reconstruction is the entire building of the roadway. Replacement
refers to replacement of the bridge deck, super structure replacement or replacement of whole
bridge. Medium term fixes includes rehabilitation. Rehabilitation is the application of structural
enhancements, such as multiple course resurfacing or concrete pavement repairs, that improves
the roadway or overlaying a bridge deck and superstructure repair to improve a bridge. Shortterm fixes include capital preventive maintenance (CPM). It applies lower-cost treatments to
slow the deterioration rate, maintain or improve the functional condition and extend the
pavement's service life. The mix of fixes strategy is used to improve the condition of the bridges
and increasing the service life of the bridges.

2.6 Life Cycle Assessment Applications
2.6.1 Background of LCA Applications
EPA defines LCA (also known as life cycle analysis, eco balance, and cradle-to-grave analysis)
as a cradle-to-grave approach for assessing systems that evaluates all stages of a product's life. It
provides a comprehensive view of the environmental aspects of the product or process. “The
term “life cycle” refers to the major activities in the course of the product’s life-span from its
manufacture, use, and maintenance, to its final disposal, including the raw material acquisition
required to manufacture the product” (EPA, 2006).
In simple words, LCA is a methodology, which is used to analyze environmental impacts of
products through its all life cycle stages. An ideal life cycle would account for all the phases of
the product. This is called Cradle to Grave approach. Similarly, LCA has different stages, which
are Cradle to Gate, which includes raw material acquisition to production stage and Gate to Gate
stage, which includes only production stage. The decision makers in the industry use LCA for

32

planning environmental strategies, product development, marketing, product comparisons, ecolabeling etc. (GaBi, 2012).

2.6.2 Bridge LCA
The life cycle of the bridges play an important role in determining the sustainability of the
system. Life cycles can be evaluated in terms of environmental or economic impacts. Assessing
the life cycle can help us become more aware of sustainable solutions for bridges. Life-cycle
models, weather through assessments, inventories or cost analysis, are complex and rely on
consistent and available historical information. In simple words, LCA is a method to assess the
environmental performance of the product or a process over its life cycle. The use of a product
throughout its life cycle may have many negative impacts on the environment. Some of the
terms, which are measured to assess the environmental performance of the product (Trusty,
2006) are Toxic releases to air, water and land; Fossil fuel depletion, CO2 emissions, Nonrenewable energy use, Global warming potential, Acidification and Acid Deposition,
Nutriphication/Eutrophication of water bodies, Stratospheric ozone depletion.

GHG emissions are one of the major contributors to the negative impacts to the environment and,
the main focus of this study developing guidelines for determining GHG emissions or the carbon
footprint of the bridges. Guidelines for calculation of GHG emissions are based on LCA
methodology. It is well known that bridge construction project involves large number of products
and processes. Cement is the most common material used in large quantity in construction.
Cement is highly energy intensive material (Worrell et. al., 2001). It consumes as well as release
high amount of energy into the surroundings during all life cycle stages like raw material

33

extraction, transportation to manufacturing facility, manufacturing, packaging, transportation to
site, use, maintenance and disposal. Cement production is energy intensive and accounts for 5%
of global anthropogenic CO2 emissions (Worrell et. al., 2001) and significant levels of SO2,
NOx, particulate matter and other pollutants. Similarly, different products and products release
significant amount of GHG emissions during their life cycle. Therefore, it is imperative to
calculate the GHG emissions of these products and processes using LCA approach and
investigate strategies to reduce these emissions. Since GHG emissions can be calculated based
on LCA methodology therefore it is important to review the LCA concepts and applications. A
number of LCA studies had been made and extensive literature is published recently. Singh,
Berghorn, Joshi and Syal (2011) had made a systematic compilation of all the Construction-LCA
related literature and presented its structured review. These research work reviews the literature
in four major categories: LCA applications for construction products selection; LCA applications
for construction systems/process evaluation; LCA tools and databases related to the construction
industry; and LCA methodological developments related to the construction industry. Current
challenges for using LCA in construction are discussed and potential areas for future research are
highlighted (Syal et. al., 2011). This study gives a good idea of the LCA methodologies and
databases for LCA.

An integrated LCA-LCCA model was developed and applied on highway overpass bridge deck,
and two alternative bridge deck designs were compared. The model is applied to alternative
concrete bridge deck design options: one conventional steel reinforced concrete bridge deck with
mechanical steel expansion joints and the other an SRC deck with Engineered Cementetious
composite (ECC) link slabs. Factors or indicators important in evaluating the sustainability such

34

as life cycle energy, greenhouse gas emissions, agency, rehabilitation, social, constructionrelated user delay costs and environmental pollutant damage costs are quantified for both
systems over a 60 year bridge design life. The integrated model consists of two integrated
elements; life cycle inventory analysis and life cycle cost model of agency and social costs. They
are further integrated into the factors that characterize the infrastructure system. These indicators
are evaluated for total 60-year service life with a traffic flow rate of 35,000 cars per day in each
direction. Study shows that ECC link slab system has a 37% cost advantage over the
conventional system, consumes 40% less total primary energy (Kendall et. al., 2008).

LCA approaches can be used to analyze the impacts of requirements of credits in the rating
system. In research study conducted, individual credits within the LEED program were critically
analyzed using life cycle approach. A case study of building was conducted to measure life cycle
energy consumption and solid waste generation to analyze the impacts of implementation of
LEED requirements (Scheuer & Keoleian, 2002).

LCA approaches can be integrated into LEED. Lloyd described that USGBC has recognized the
benefits of using quantitative and holistic life cycle information and an “LCA into LEED”
program has been initiated to determine how best to integgrate LCA into LEED Building for
Economic and Environmental Sustainability (BEES) which is an LCA software tool developed
by National Standards of Intitute and Technology takes a life cycle approach to building
materials and focus on both life cycle environmental and cost data. It was shown that BEES can
be used to integrate LCA itno LEED (Lloyd, 2005).

35

There are two ways to conduct an LCA - using an input-output based LCA, or a process based
LCA. Economic input-output based LCAs are based on economic transactions and resource
interactions between an exhaustive set of economic sectors. “The Economic Input-Output Life
Cycle Assessment (EIO-LCA) method estimates the materials and energy resources required for,
and the environmental emissions resulting from, activities in our economy. It is one technique
for performing a life cycle assessment, an evaluation of the environmental impacts of a product
or process over its entire life cycle”.

EPA has developed a report, which gives an overview of sources and magnitude of construction
and GHG emissions and ways to reduce them. The opportunities to reduce GHG emissions are
presented based on best available sources and information. EPA describes that Fuel selection,
equipment idling, electricity use, equipment maintenance, equipment selection and material
recycling are the construction activities that results in GHG emissions and have the most
influence on contractors potential ability to affect emissions. Similarly, material selection,
employee commuting, materials shipment and vegetation removal have some influence and site
selection and structural design and performance have little influence (EPA, 2009).
Emphasis on recycling and reusing of materials is placed as GHG emissions released during the
manufacturing and transportation of the construction materials are avoided. Therefore, recycled
materials should be used on the project like Fly ash, blast furnace slag and recycled steel. Fly ash
and blast furnace slag can be used as supplemental cementitious materials and replace a portion
of the cement. The emission factor of such type of blended cement is greatly reduced. Table 2.3
shows the environmental impact score of the traditional Portland cement and the blended cement
(Huntzinger & Eatmon, 2009). The software tool SimaPro was used to assess the environmental

36

impact score of the two types of cement using LCA methodology. It can be seen that use of
blended cement reduces GHG emissions by 21.6% (Huntzinger & Eatmon, 2009).
Table 2.3: Comparison of Environmental Impacts of Two Types of Cement (Huntzinger &
Eatmon, 2009)
Environmental Impact

Traditional Portland

Blended

Category

Cement

Cement

Greenhouse

.088

.069

Acidification

.043

.034

Also, recycling steel reduces GHG emissions and save energy by 56%. Also recycling 1 ton of
steel conserves 2500 pounds of iron ore, 1400 pounds of coal and 120 pounds of limestone
(West, 2012).

2.6.3 Available LCA Tools
LCA tools are the applications to conduct LCA of construction products and systems. These can
be used to quantify energy and material usage, as well as quantification of environmental
releases across all the life cycle stages. LCA tools can widely be used for environmental
labeling, product environmental improvement, ecodesign and policy evaluation (Menke et. al.,
1996). Menke, Davis and Vigon (1996) identified comprehensive list of 37 LCA tools and the
related literature was reviewed.

LCA tools measures the environmental impacts primarily across a five set of environmental
indicators which are fossil fuel use; global warming potential, toxic releases to air; toxic releases

37

to water and solid waste generation. Mukherjee and Cass (2011) surveyed GHG impact
assessment tools shown in Table 2.4 and classified according to the institution type such as
Academic tools, Government and Industry.
Table 2.4: GHG Impact Tools (Adopted from (Mukherjee & Cass, 2012) )
Institution Type
Life Cycle
Assessment
Government

GHG Impact Tools
Emission
Calculators

NREL-LCI

SGEC Tool

Academic State

EIO-LCA PaLATE

Industry

Road Construction
Emission Model
GreenDOT
CHANGER
e-CALC
AggRegain

SimaPro
AsPECT

38

Rating/Point
Systems
FHWA SelfEvaluation Tool
Greenroads
GreenLITES
I-LAST
GreenroadsTM

CHAPTER 3
FRAMEWORK FOR ASSESSING SUSTAINABILITY IN BRIDGE DESIGN,
CONSTRUCTION AND MAINTENANCE

3.1 Definition of the Framework
Based on the detailed content analysis discussed in the previous sections, the framework is
divided into three sections: 1) Design, 2) Construction, and 3) Maintenance. The design section
entails site, materials and others while construction section is based on construction techniques,
water use, renewable energy, construction waste, and fuel efficiency. The maintenance section
highlights sustainability issues in bridge painting, cleaning, drainage and impacts on aquatic and
wildlife. Each category is divided into various criteria. The description, intent and requirements
have also been established. Table 3.1 shows the list of criteria and construction standards that
were used to establish the requirements for each criterion. The lists of criteria were obtained
based on detailed content analysis. The final list of the criteria included in the framework is
based on MDOT suggestions, which are based on their requirements for bridges in Michigan.

39

Table 3.1: Criteria Table
Criteria

Title

Intent

Standards

1. Design
1.1 Site
Site Selection

To avoid environmental impacts Appendix M of Construction General Permit of US
due to the location of a site.
department of Environmental Protection Agency (EPA).

Criteria
1.1.1

http://www.epa.gov/npdes/pubs/cgp_appendixm.pdf;
Appendix D of EPA’s Construction general permit.
http://www.epa.gov/npdes/pubs/cgp_appendixd2011.pdf.

Criteria
1.1.2

Criteria
1.1.3

Historic
Preservation

Site To avoid development of historic Section 106 of the National Historic Preservation Act;
sites and reduce the socio-cultural
environmental impact from the State Historic Preservation Office (SHPO);
location of a bridge on a site.
2311 Cultural Resources Survey, P/PMS Task Manual
MDOT.

Soil
Erosion
and To reduce pollution such as soil
Sedimentation Control erosion, sedimentation and dust
and particulate matter generation
resulting due to construction
activities.

Principles of Runoff Control for Roads, Highways, and
Bridges; Erosion, Sediment and Runoff Control for
Roads and Highways, Environmental Protection Agency
(EPA); http://water.epa.gov/polwaste/nps/runoff.cfm;
Part 1.1.2: Soil Erosion and Sedimentation Control,
Chapter 9, Storm-water Best Management Practices
(BMP’s);
Michigan
(MDEQ).

40

Department

of

Environmental

Quality

Table 3.1 (cont’d)
Criteria

Title

Intent

Standards

Brownfield
Redevelopment

To rehabilitate contaminated sites Section 2.4, Contamination Investigation (2800 Series),
and
reduce
pressure
on P/PMS task manual, MDOT;
undeveloped land.
EPA 2011, Environmental Protection Agency,
Brownfield Sites, Region 4: Land Revitalization and
Reuse.

Storm-Water
Management

To reduce the quantity of
pollution and run-off from stormwater that is discharged into
surface waterways or stormsewers.

Criteria
1.1.4

Criteria
1.1.5

Michigan
(MDEQ);

Department

of

Environmental

Quality

Chapter 9, Storm-water Best Management Practices,
MDOT Drainage Manual;
MDOT Soil Erosion and Sedimentation Control Manual.

1.2 Materials
Use
of
Materials
Criteria
1.2.1

Recycled To increase the demand for
materials
that
incorporate
recycled
materials,
thereby
reducing environmental impacts
resulting from extraction and
processing of virgin materials.

41

Section 3.12.3 "General Recommendations for DOTs
with Regard to Recycling and Waste Management" of
Chapter 3 "Designing for Environmental Stewardship in
Construction & Maintenance" 3.12.3

Table 3.1 (cont’d)
Criteria
Criteria
1.2.2

Criteria
1.2.3

Title

Intent

Standards

Supplemental
Cementitious Materials

To reduce the embodied energy
associated with the cement by
replacing a part of it with
supplemental cement. materials

Section 3.12.3 “General recommendation for DOT with
regard to recycling and waste management” of chapter 3
“Designing for environmental stewardship in
construction and maintenance” 3.12.3.

Reduction in Quantity To reduce the quantity of Development of Rating System for Sustainable Bridges"
materials in bridges to avoid MS Thesis, Massachusetts Institute of Technology, MA
of Materials
environmental impacts associated by Lauren Hunt, 2004
with the life cycle of materials.
Material Reuse

To reuse bridge materials and
attachments to reduce demand for
virgin materials and reduce
waste.

Regional Materials

To
increase
demands
for Material and Resource Credit 5 of LEED® 2009.
materials and products that are
extracted
and
manufactured
within the region, thereby
supporting the use if indigenous
resources and reducing the
environmental impacts resulting
from the transportation

Criteria
1.2.4

Criteria
1.2.5

42

Section 5.7.14 "Aluminum Sign Recycling and
Chromate Coating Elimination" and Section 5.7.3
Recycled Concrete Material/Aggregate (RCM/RCA) of
Chapter 5 "Pavement, Materials, and Recycling".

Table 3.1 (cont’d)
Criteria

Title

Intent

Standards
1.3 Other

Renewable Energy Use
Criteria
1.3.1

Criteria
1.3.2
Criteria

Bicycle
Pathways

Pedestrian To promote the use of alternative Bicycle and Pedestrian Legislation in Title 23 United
transportation in order to reduce states Code (U.S.C), Office of Planning, Environment
energy demand and reduce and Reality (HEP), FHWA.
pollution due to automobile use.
Title

Lane Adaptability
Criteria
1.3.3

Life
Cycle
Analysis
Criteria
1.3.4

To promote the use of renewable ANSI/ ASHRAE/ IESNA Standard 90.1-2007 (Exterior
energy on site thus reducing Lighting).
economic and environmental
impacts associated with nonrenewable energy use.

Intent

Standards

To provide a framework for High-Performance
Materials
for
Substructures,
additional
lanes
for
any Foundations, and Earth Retaining Systems Workshop,
Bridge and Structures Research and Development
unforeseen conditions.
(R&D), Federal Highway Administration Research and
Technology, FHWA, Publication Number: FHWAHRT-08-058, February 2009.
Cost To estimate the overall cost of the NCHRP, National Cooperative Highway Research
project alternatives and select the Program, 2003. “Bridge Life Cycle Cost Analysis
design that ensures the facility Report 483”.
will provide the lowest overall
cost of the ownership consistent
with its quality and function

43

Table 3.1 (cont’d)
Criteria

Title

Intent

Standards

2. Construction

Criteria 2.1

Criteria 2.2

Criteria

Accelerated
Construction
Techniques

Bridge The objective is to reduce the Federal Highway Administration (FHWA).
construction time of the project
thereby reducing environmental
and traffic mobility impacts.

Corrosion
Resistant To prevent bridge reinforcement
from corrosion by penetration of
Steel Reinforcement
sodium chloride thus preventing
the
bridge
from
early
deterioration and extending the
service life of the bridge.

Title
Efficient Water Use

Criteria 2.3

Criteria 2.4

Intent
To conserve
efficient use
construction.

Performance of epoxy-coated rebar in bridge decks
volume 60-No. 2, FHWA;
Stainless steel reinforcement, MDOT bridge design
manual section 7.04;
Epoxy coated rebar bridge decks; expected service life,
MDOT bridge design manual section 12.
Standards

water through Specification C94 for Ready Mixed Concrete;
during bridge
Section 911 of 2012 MDOT standard specifications for
construction.

Non-road Equipment To reduce air emissions from Project Development Criteria 27, “Sustainable Highways
Self Evaluation Tool” FHWA, US Department of
Emission Reduction
non-road equipment.
Transportation, 2011

44

Table 3.1 (cont’d)
Criteria

Title
Construction
Management

Criteria 2.5

Criteria 2.6

Intent

Standards

Waste To divert waste generated in Section 01 74 19 - Construction Waste Management,
construction and demolition from EPA.
disposal and in landfills and
incineration.

Use of Certified Wood

To
encourage
best
management practices.

forest Designing and Building with FSC, Forest Stewardship
Council, Forest Product Solutions.

3. Maintenance

Criteria 3.1

Efficient
Inspection To use efficient inspection
technologies and processes for
Technologies
proper
maintenance
action
decision thus enhancing the
service
life
and
reducing
associated
environmental
impacts.
Bridge
Painting/Coating

AASHTO, 2009, Chapter 7, Bridge Maintenance,
“Center of Environmental Excellence by AASHTO”,
www.environment.transportation.org;
MDOT Bridge Inspection Manuals and MDIOT
Inspection
Manual,
Michigan
Department
of
Transportation.

To prevent bridge components OSHA; CFR 29 1926.62, Lead in Construction;
from deterioration due to
corrosion thus increasing the age Zinc-Rich Bridge Coatings, FHWA Bridge Coatings
Technical Note: Zinc-Rich Bridge Coatings;
of bridges.
Clean Air Act Amendments;
Society for Protective Coatings (SACE);
National Association of Corrosion Engineers (NACE)

45

Table 3.1 (cont’d)
Criteria

Title
Bridge
Painting/Coating

Intent

Standards

To prevent bridge components OSHA; CFR 29 1926.62, Lead in Construction;
from deterioration due to
corrosion thus increasing the age Zinc-Rich Bridge Coatings, FHWA Bridge Coatings
Technical Note: Zinc-Rich Bridge Coatings;
of bridges.
Clean Air Act Amendments;

Criteria 3.2

Society for Protective Coatings (SACE);
National Association of Corrosion Engineers (NACE);
GS11 Green Seal Environmental Standard for Paints and
Coatings.

Bridge Cleaning

Criteria 3.3

Bridge Deck Drainage
Criteria 3.4

To clean components of bridges
susceptible to dirt, bird-drop
accumulation etc. thus increasing
efficiency
of
the
bridge
components
and
lessen
maintenance requirements.

Drainage System cleaning, Pavement Cleaning, MDOT
Scoping
Manual,
Michigan
Department
of
Transportation;
“Part 7.1.3, Bridge Cleaning; Chapter 7, Bridge
Maintenance, Center for Environmental Excellence by
AAHSTO” American Association of State and
Transportation Officials. NCDOT Guidelines for
Managing Bridge Wash Water Version 1.0.

To avoid impacts on the deck Proper Drainage Reduces Roadway Problems. Nevada
structure and reinforcing bars due Milepost, Nevada’s Technology Transfer Quarterly, Vol.
to inefficient drainage.
12, No. 1, (Spring 2002) p. 1.

46

Table 3.1 (cont’d)
Criteria

Title

Intent

Standards

Avoiding
and To avoid impacts on fish and Federal Endangered Species Act;
Minimizing Impacts to wild life due to maintenance
Rivers and Harbor Act;
Fish and Wild Life
activities
Criteria 3.5

Clean Water Act;
Michigan
(MDEQ).
Corrosion
Materials

Criteria 3.6

Criteria 3.7

of

Environmental

Quality

Control To prevent or minimize the MDOT standard specifications for construction section
corrosion of bridge elements due 712.03
to the penetration of sodium
Michigan State University Report, 2000, “Repair of
chloride.
Corrosion Damaged Columns Using FRP Wraps”

Bridge Deck Joints and To minimize or eliminate poorly Evaluation of various types of bridge deck joints, Final
maintain bridge deck joints and Report 510, Baker Engineering and Energy, Arizona
Seals
seals thus maintaining the service Department of Transportation;
life of the bridge.
Michigan Department of Environmental Quality
(MDEQ).
Snow and Ice control

Criteria 3.8

Department

To implement snow and ice Sustainable Highways Self-Evaluation Tool, FHWA,
control techniques to reduce USDOT
associated impacts of snow and
ice on the bridge.

47

3.2 Green Rating System for the Bridges
An extensive content analysis of MDOT's current practices as well as existing sustainability and
bridge related sources was carried out to develop the framework. After going through a
significant research session by consulting different journals, articles, books and websites,
MDOT's design and construction manuals, New York State Department of Transportation
(NYSDOT) Leadership In Transportation and Environmental Sustainability Project Design
Certification Program (NYSDOT, 2008), LEED®, 2009 and a master's thesis on "development of
a rating system for sustainable bridges" provided significant guidance in selecting and defining
categories and credits for the framework to assess in this work. Current sustainable practices in
design, construction and maintenance followed by MDOT have also been reviewed. For this
purpose MDOT manuals such as MDOT scoping manual, MDOT design manual, MDOT
drainage manual and MDOT bridge preservation matrix have been reviewed.

MDOT follows best management practices for storm water management (Quality and Quantity
Control), measures to avoid soil erosion and sedimentation control, and efficient drainage
systems. MDOT, under agreement with the MDEQ is also certified as a storm water management
operator on all transportation related construction sites statewide, and requires project managers
to attend training to keep certifications current. In addition to these, MDOT uses recyclable
materials such as concrete incorporating wastes such as fly ash and recycled-in-place asphalt
pavements. Fiber Reinforced Plastics (FRP) is also used by MDOT for the bridge decks and
other structural member applications. Various studies have demonstrated that FRP is more
effective than other material with regard to the amount of CO2 emissions and is corrosion
resistant material.

48

3.2.1 Category 1-Design
The design category focuses on measures that can be taken during the design of bridges. Creating
plans and employing methods in the design that result in achieving sustainability will be the
intent of this category. The design principles will be consistent with MDOT policy and
standards. MDOT has already been practicing several sustainable techniques and has
incorporated these criteria in their design strategies, which are environmentally responsible. The
design section is divided into sites, materials and other which are further subdivided into various
criteria. Guidance is given under each criterion for assigning points to the particular category.
This study describes in detail the construction and maintenance category while details on design
category can be found in MS thesis completed by Awan (2012), which is based on the research
work for MDOT titled as “Implementation of Sustainability in Bridge Design, Construction and
Maintenance (MDOT, 2012).

3.2.2 Category 2-Construction
Construction is an important phase, which incorporates the rehabilitation, replacement or
addition of an entire structure. A successful project includes timely completion, costeffectiveness and quality. The following sections will define the criteria and standards
recommended to incorporate in bridge projects during the construction phase. These credits will
help in promoting a sustainable environment and lessening the impacts on nature by integrating
recycled or reused materials, efficient water use, managing waste material on-site, utilizing
sustainable energy resources and employing fuel efficient vehicles in the construction process.

49

Criteria 2.1: Accelerated Bridge Construction Techniques (ABCT) (14 Points)
Description:
Accelerated construction is used to achieve the construction of structures in a shortest possible
time while decreasing delays and traffic disruption. It is not just building structures rapidly but
also entails a variety of techniques, processes, and technologies to achieve the desired result of
reducing congestion due to construction while improving quality. These techniques are used for
the construction of new bridges and also the replacement of existing bridges (Ralls, 2007).

Intent:
The objective is to reduce the construction time of the project thereby reducing environmental
and traffic mobility impacts.

Requirements:
Adopt one of the outlined techniques below:
Self-Propelled Modular Transports (SPMT): It offers numerous marketing strengths due to the
straightforward, demonstrable, easily comprehendible nature of its value proposition. Saving
time, money (in terms of the costs of travel delay), and possibly lives, by removing older
structures and replacing them in minutes or hours with new structures constructed offsite is an
obvious improvement over conventional methods (AASHTO, 2010).

Incremental Launching: In this method, bridge is prefabricated in 50-100 feet long units under
factory conditions behind an abutment and bridge is launched by sliding it on bearings into the
final position without the aid of scaffolding. The advantages are less first cost due to less

50

equipment and less labor and less maintenance cost (Leshko, 2007). This can be done through
super-structure roll in, super-structure lift in and using pre-fabricated bridge elements and
components.

Scoring Criteria:
Points can be scored based on the percentage of time saved by using ABC techniques as shown
in Table 3.2. The points will be awarded based on the time reduced due to the application of
accelerated bridge construction techniques. The points will be awarded based on the following
criteria:
Table 3.2: Scoring Criteria for Accelerated bridge Construction Techniques
% Reduction in Time
0-10
11-25
26-40
41-60
61+

Points Scored
3
5
7
10
14

Standards/Resources:
• Accelerated Bridge Construction Techniques, US department of Federal Highway
Administration (FHWA)

51

Criteria 2.2: Corrosion Resistant Steel Reinforcement (8 Points)
Description:
Chloride salt-based deicing chemicals the most common of which is sodium chloride are used for
snow and ice control on bridges in winter. Sodium chloride can penetrate through cracks and
over time through diffusion and acts as catalyst for reinforcement corrosion. This is one of the
primary reasons of deterioration of the structure. Adding corrosion resistant steel reinforcement
helps establish a barrier that attempts to block the penetration of water, oxygen, and other
elements that promote corrosion of the reinforcement (Boatman, 2010).

Intent:
To prevent bridge reinforcement from corrosion by penetration of chloride thus preventing the
bridge from early deterioration and extending the service life of the bridge

Requirements:
a) Consider using corrosion resistant reinforcing steel such as epoxy coated reinforcement,
stainless steel reinforcement, stainless steel clad reinforcement.
b) Stainless steel industry share of CO2 emissions could be around 12% of global emissions.
Stainless steel contributes greatly towards sustainability and it leaves reduced carbon
footprint (Gopal, 2006).

Scoring Criteria:
4 Points will be awarded if epoxy coated reinforcement are used on the project and 8 points will
be awarded for both stainless steel reinforcement and epoxy coated reinforcement.

52

Standards/Resources:
•

Performance of epoxy-coated rebar in bridge decks volume 60-No. 2, FHWA

•

Stainless steel reinforcement, MDOT bridge design manual section 7.04

•

Epoxy coated rebar bridge decks; expected service life, MDOT bridge design manual section
12

•

ASTM E937 - 93(2011) Standard Test Method for Corrosion of Steel by Sprayed FireResistive Material (SFRM) Applied to Structural Members

•

ASTM A1035 (low carbon, chromium) – MMFX2

•

Stainless steel conforming to ASTM A955 – UNS designations: S24100, S30400, S31603,
S31653, S32101, S32201, S32205

•

Stainless steel clad bars conforming to AASHTO MP13M

53

Criteria 2.3: Efficient Water Use (2 Points)
Description:
Water is one of the most valuable resources on the planet earth, and although the United States
has a copious supply, it is not evenly distributed throughout the country. Recent droughts
illustrate that many areas are severely undersupplied. A truck roughly utilizes around 50 to 200
gallons of water in washing out (Lob, 2010). Therefore, innovative and cost-effective water
efficiency strategies will help in saving this natural resource.

Intent:
The objective is to efficiently use water during the bridge construction and incorporate water
efficiency and conservation in equipment washing. It entails considerable reduction in use of
potable water and employs on-site resources in order to lessen demand on municipal water
supply.

Requirements:
Consider use of gray water in making ready mix concrete (ASTM, 2009). Consult Section 911 of
the 2012 MDOT Standard Specifications for the standard limits the amount of total solids; total
organic content and alkalinity of non-potable water that can be used in concrete mix designs.
Any gray water used that has values higher than those listed Table 911-1 will lower the concrete
life expectancy and therefore cannot be used. Store, recycle and reuse water already utilized for
equipment washing (Lob, 2010). Other means to decrease the water usage could be using
recycled water in Plant and truck washing, Plant and yard wash down, Slump adjustment
Aggregate sprinklers.

54

Scoring Criteria:
Compute the quantity of gray water or recycled and reused water used on the project as a
percentage of quantity of water if only municipal water is used. Points can be scored according
to the percentage of water saved as shown in Table 3.3 using any of the outlined or other
techniques.
Table 3.3: Scoring Criteria for Water Use Reduction
% Water reduced using
water efficiency techniques
20
30

Score
1
2

Standards/Resources:
•

Specification C94 for Ready Mixed Concrete

•

Section 911 of the 2012 MDOT Standard Specifications

55

Criteria 2.4: Non-Road Equipment Emission Reduction (2 Points)
Description:
Air emissions from construction equipment contribute significantly to the degradation of the
environment. Therefore, it is imperative to use such type of equipment, which produces lesser
emissions than conventional ones. “Non-road engines are all internal combustion engines except
motor vehicle (highway) engines, stationary engines (or engines that remain at one location for
more than 12 months), engines used solely for competition, or engines used in aircraft. The nonroad standards cover mobile non-road diesel engines of all sizes used in a wide range of
construction, agricultural and industrial equipment” (EPA, 2004). So, Non-road equipment is
used in construction and not on roads like cars, buses etc.

Intent:
The objective is to reduce air emissions from non road equipment.

Requirements:
“Use non-road equipment that meet at least one of the following criteria” (FHWA, 2012).
a) Have engines that meet the current U.S. Environmental Protection Agency (EPA) Tier
emission standards (Tier 3/Interim Tier 4 as of April 2011) in effect for non-road engines of
the applicable engine power group.
b) Have diesel retrofit devices for after-treatment pollution control verified by EPA or the
California Air Resources Board (CARB) for use with non road engines.”

56

Scoring Criteria:
One point will be awarded if 50% of the equipment meets the above requirement.
Two points will be awarded if 75% of the equipment meets the above requirement.

Standards/Resources:
Project Development Criteria 27, “Sustainable Highways Self Evaluation Tool” FHWA, US
Department of Transportation, 2011

57

Criteria 2.5: Construction Waste Management (4 Points)
Description:
Waste management entails identify, collect and remove the waste materials from the construction
site to the appropriate land. A construction waste management plan is the first step in managing
construction waste because it requires contractors to establish a system for tracking waste
generation and disposal during construction.

Intent:
The objective is to divert construction and demolition debris from disposal in landfills and
incineration facilities. Redirect recyclable recovered resources back to the manufacturing process
and reusable materials to appropriate sites (USGBC, 2009).

Requirements:
Recycle and/or salvage nonhazardous construction and demolition debris. Develop and
implement a construction waste management plan that, at a minimum, identifies the materials to
be diverted from disposal and whether the materials will be sorted on-site or comingled. In
addition, establish a comprehensive plan to assist the contractor in proper disposal of the hydrodemolition water. This plan entails the collection, management and disposal of hydro-demolition
water from a hydro-demolition process used for bridge deck restoration (North Carolina
Department of Transportation, 2008). Calculations can be done by weight or volume, but must
be consistent throughout. Develop a construction waste management plan that results in end of
project rates for salvage/ recycling of 95 percent by weight of construction and demolition waste
(EPA, 2007).

58

Scoring Criteria:
The points will be awarded based on percentage of total construction waste diverted from the
landfills as shown in Table 3.4. An example for calculations is shown in Table 3.5.
Table 3.4: Scoring Criteria for Construction Waste Management
% Construction Waste Diverted
20
40
60
80

Points
1
2
3
4

Table 3.5: Example Calculations for Construction Waste Management
Material
Description

Diversion

Quantity of Diverted
Material

Recycling
Concrete
Steel Collector
Steel
Reuse
Wood
Landfill
Mixed Waste
On-site Reuse
Rubble
Total Construction Waste Diverted
Total of all Construction Waste
% of Construction Waste Diverted

210.6
6.5
8.0
52.0
60.0
337.1
500.00
67.5 %

Unit
Tons
Tons
Tons
Tons
Tons
Tons
Tons

Standards/Resources:
•

Section 01 74 19 - Construction Waste Management, EPA

•

Section 03SP712(C), Special Provision for Managing Hydro-demolition Runoff Water,
MDOT

59

Criteria 2.6: Use of Certified Wood (1 Point).
Description:
Forest Certifications has grown rapidly over the last decade. This practice is used to effectively
use and manage nature’s resources. “The Forest Stewardship Council (FSC) is an international
not-for-profit, multi-stakeholder organization established in 1993 to promote responsible
management of the world’s forests. Its main tools for achieving this are standard setting,
independent certification and labeling of forest products. This offers customers around the world
the ability to choose products from socially and environmentally responsible forestry”. “FSC
certification for wood products represents a real approach to assuring customers that the
product they choose come from forest that were managed in a sustainable manner” (FSC, 2011).

Intent:
To encourage the best forest management practices.

Requirements:
“Use a minimum 50% (based on cost) of wood based materials and products that are certified in
accordancewith the Forest Stewardship Council’s principles and criteria for wood building
components” (USGBC, 2009). “This should include, but not limited to, general dimensional
framing, and non-rented temporary construction applications such as bracing, concrete form
work and predestrian barriers” (Hunt, 2004). Preservative treated woods also provide
environmental, economical and social benefits for our communities (McConnell & Irby, 2011).

60

Scoring Criteria:
1 point for using certified wood in the project.

Standards/Resources:
•

“Designing and Building with FSC”, Forest Product Solutions, Forest Stewardship Council.

61

3.2.3 Category 3-Maintenance
Majority of the bridges built in around 1960’s and 1970’s need significant repair and
maintenance actions (Helms, 2011). Lead and Chromate based paints and coatings removal may
have significant impacts on the environment, workers and public. This section outlines the
requirements of inspection technologies, bridge painting, cleaning, deck drainage and impacts to
fish and wild life that should be met in order to reduce environmental impacts associated with
these.

62

Criteria 3.1: Efficient Inspection Technologies (3 Points)
Description:
Inspection technologies play a very important role in collecting data and reliability indices of
various structural and environmental conditions. Use of efficient equipment and processes can
help in assessing the conditions of the bridge more efficiently and accurately. Efficient and
accurate data is required to make decisions regarding various maintenance actions. Therefore, it
is recommended to use efficient inspection technologies and processes for assessing the bridge
conditions for proper maintenance action decisions. Taking proper and timely maintenance
actions would ensure increasing service life and be cost-effective.

Intent:
To use efficient inspection technologies and processes for proper maintenance action decision
thus enhancing the service life and reducing associated environmental impacts.

Requirements:
a) Follow Recommended Framework for a Bridge Inspection QA/QC Program of National
Bridge Inspection Standards, FHWA. The framework describes the quality control and
quality assurance procedures for accuracy and consistency in the bridge inspections. The
framework outlines documentation of QA/QC program, Quality Assurance (QA) procedures,
and Quality control (QC) procedures.
b) Use of specialized bridge equipment such as under bridge inspection vehicles, mobile
inspection platforms, non-destructive evaluation equipment and data collection and analysis

63

equipment (Lwin, 2005) for efficient data collection and to allow workers to maneuver safely
into position allowing for hands-on inspection and maintenance work.

The office of bridge technology, FHWA, outlines a policy regarding the use of federal-aid
funds, specifically highway bridge replacement and rehabilitation programs (HBRRP) funds
for the purchase or rent of the specialized inspection equipment. Federal HBRRP funds may
also be used for the installation of permanent features that facilitate inspection activities on
highway bridges as defined in 23 CFR 650.305. Such features as handrails, anchor points for
a horizontal lifeline, and catwalks would be a few examples. In addition to HBRRP funds,
National Highway System, Surface Transportation Program, and State Planning and
Research funds may be used for development, establishment, and implementation of bridge
management systems and associated data collection activities.

Scoring Criteria:
2 points for meeting the first requirement only.
2

points for meeting both requirements.

Standards/ Resources:
•

Recommended Framework for a Bridge Inspection QA/QC Program, National Bridge
Inspection Standards (NBIS), Bridge Technology, Federal Highway Administration and
Funding For Bridge Inspection Equipment And Access Features, National Bridge Inspection
Standards (NBIS), Bridge Technology, Federal Highway Administration (FHWA)

64

•

MDOT Bridge Inspection Manuals and MDOT Inspection Manual, Michigan Department of
Transportation

65

Criteria 3.2: Bridge Painting/Coating (6 Points)
Description:
Bridge painting and cleaning are important part of the bridge life cycle. The painting enhances
the aesthetics and protects the steel bridge elements against corrosion and other weather
deterioration (AASHTO, 2012).Paints should be used to slow corrosion cause by moisture, air,
and oxidizing chemicals (Chang, Abdelrazig, & Chen., 2000). An effective bridge painting and
cleaning plan is required as certain activities can be expected during bridge painting and cleaning
such as traffic lane closures, pedestrian and bicycle detours, moderate construction noise and
dust and normal work hours of 7 AM to 4 PM with occasional night time and weekend works.
Paint should be used to slow corrosion cause by moisture, air, and oxidizing chemicals.
Typically, bridge abutments and piers are made of concrete. The beams and diaphragms made of
steel are what needs to be painted.

Intent:
To prevent bridge components from deterioration due to corrosion thus increasing the life
expectancy of bridges and also protect the workers and the environment from paint related byproducts.

Requirements:
a) Utilize best practices to protect workers and environment during lead paint removal and
remove lead from existing structures and replace with zinc-rich type 4 systems (AASHTO,
2012).

66

b) Consider applying coating to the structural steel or reinforcement i.e. consider using zinc rich
coatings that provide galvanic protection with additional coatings of epoxy and urethane
paints (MDOT, 2012). Consider galvanizing, metallizing methods and inorganic zinc-rich
paints (Kline, 2009). The concentration of zinc powder in the mixed coating is >80% by
weight for the best performing inorganic zinc paints. AASHTO M300 covers zinc-rich
coatings for steel (FHWA, 2012).

Scoring Criteria:
3 points are awarded, if zinc rich coatings are used for all the components and 6 points are
awarded for meeting all the requirements.

Standards/Resources:
•

Zinc-Rich Bridge Coatings, FHWA Bridge Coatings Technical Note: Zinc-Rich Bridge
Coatings

•

Clean Air Act Amendments

•

Society for Protective Coatings (SACE)

•

National Association of Corrosion Engineers (NACE)

•

GS11 Green Seal Environmental Standard for Paints and Coatings

67

Criteria 3.3: Bridge Cleaning (2 Points)
Description:
Bridge cleaning is important in bridge maintenance. It consists of cleaning of all bridge
components vulnerable to dirt, bird-drop accumulation, accumulation of any chemicals etc. by
using a suitable means or method such as hand tools, air blasting or water jetting. Bridge
cleaning may increase the life of bridge components significantly (AASHTO, 2009).

Intent:
To clean components of bridges vulnerable to dirt, bird drop accumulation etc. thus increasing
the longevity of the bridge components and lessening future maintenance requirements.

Requirements:
Bridge components subjected to dirt, bird drop accumulation etc. should be cleaned periodically
by using hand tools, air blasting or preferably water jetting. Specifically:
a) Use proper respirators to avoid inhalation of dust or any other material.
b) Bridge components such as decks, pier caps, abutment seats, select beam flanges, wing walls,
bearing systems, open expansion joints should receive water flush.
c) Use best practices in channel maintenance for cleaning of weeds, float, debris etc. from the
vicinity of the bridge.
d) Develop a management plan for containment of wash water i.e. to collect, sample, test,
monitor and disposal of wash water. Avoid entering wash water into storm sewers, surface
water, wetlands, ditches, floodplains etc., unless in compliance with the local standards.
e) Determine the pollutant level of the wash water to select suitable disposal method, such as

68

disposing it off in surface waters or below the ground surface.
f) The wash water may also be hauled to a licensed treatment or disposal facility, in accordance
with the approved wash water sampling and disposal plan (North Carolina Department of
Transportation, 2008).

Scoring Criteria:
•

1 point will be awarded for developing schedule of cleaning operations.

•

2 points will be awarded if wash water management plan is also developed.

Standards/Resources:
•

Drainage System cleaning, Pavement Cleaning, MDOT Scoping Manual, Michigan
Department of Transportation

•

“Part 7.1.3, Bridge Cleaning; Chapter 7, Bridge Maintenance, Center for Environmental
Excellence by AAHSTO” American Association of State and Transportation Officials.

•

NCDOT Guidelines for Managing Bridge Wash Water Version 1.0

69

Criteria 3.4: Bridge Deck Drainage (2 Points)
Description:
Bridge deck drainage is an important feature and care should be given while designing and
maintaining the deck drainage. It should be designed to accommodate runoff. Effective design
and maintenance of deck drainage is required to prevent the deck structure and reinforcing steel
from corrosion due to deicing salts and moisture (AASHTO, 2009).

Intent:
To avoid impacts on the deck structure and reinforcing bars due to inefficient drainage.

Requirements:
a) Gutter flow from roadways should be intercepted before it reaches a bridge;
b) Avoid zero gradients and sag vertical curves on bridges;
c) Larger grates and inlet structures can be used onto the subsequent roadway sections to collect
runoff from bridge decks immediately (AASHTO, 2009).

Scoring Criteria:
1 point for meeting any of the two requirements.
3 points for meeting all of the requirements.

Standards/Resources:
•

"Proper Drainage Reduces Roadway Problems." Nevada Milepost, Nevada’s Technology
Transfer Quarterly, Vol. 12, No. 1, (Spring 2002) p. 1.

70

Criteria 3.5: Avoiding and Minimizing Impacts to Fish and Wild Life (1 Point)
Description:
Bridge maintenance operations can severely disrupt the natural flow of river and stream
ecosystems. The road crossings like bridges and culverts have a growing concern in altering
habitats and disrupting the river and stream current (Jackson, 2003). Stream crossing methods
include bridges, open-bottom or arch culverts, box culverts, and pipe culverts. Depending on the
type of crossing, its size, method of installation, and maintenance, a crossing may have many or
relatively few adverse impacts on a river or stream ecosystem.

Intent:
To avoid impacts on fish and wild life due to maintenance activities.

Requirements:
a) Seek ways to build more durable structures, and in an environmentally sound fashion.
Identify opportunities to Avoid and Minimize Impacts
b) Scheduling Maintenance and Improvements to spend minimal time in sensitive environments.
Practices may include scheduling bridge maintenance to avoid egg spawning incubation,
juvenile rearing and downstream migration periods of fish (AASHTO, 2009).

Scoring Criteria:
•

Point is awarded for meeting the requirement.

71

Standards/Resources:
•

Federal Endangered Species Act

•

Rivers and Harbor Act

•

Clean Water Act

72

Criteria 3.6: Corrosion Control Materials (3 Points)
Description:
This criterion will address corrosion control materials that can be used during rehabilitation and
maintenance of bridges.

Intent:
To prevent or minimize the corrosion of bridge elements due to the penetration of chloride based
deicers. This minimizes early deterioration of the structure. Each recommended method would
either result in an increased amount of time between maintenance cycles or extend the bridge’s
service life.

Requirements:
a) Consider using galvanic anodes in all concrete patches that extend below the top layer of
reinforcement. Only galvanic anodes listed on MDOT’s QPL can be used.
b) Consider using Carbon Fiber Reinforced Polymer (CFRP) wrap. This increases the strength,
is lightweight and provides additional corrosion resistance.

Scoring Criteria:
2 points are awarded, if any one requirement is met.
3 points are awarded for meeting both the requirements.

Standards/Resources:
•

MDOT standard specifications for construction section 712.03

73

•

Michigan State University Report, 2000, “Repair of Corrosion Damaged Columns Using
FRP Wraps”

74

Criteria 3.7: Bridge Deck Joints and Deck Joint Seals (4 Points)
Description:
Bridge deck joints are important components for proper functioning of the structure. Various
factors such as temperature change, deflection caused by loads, creep and shrinkage of concrete,
stream or ice flow and longitudinal force of vehicles causes bridge to expand and contract.
Bridge deck joints allow the bridge to expand and contract while protecting critical elements
underneath the joint.

Intent:
To minimize or eliminate poorly maintained bridge deck joints and seals thus maintaining the
service life of the bridge

Requirements:
Consider:
a) Eliminating bridge deck joints (when possible) or moving joints off bridge with the use of
sleeper slabs.
b) Discontinue to the extent possible the use of compression seals in new construction,
replacement, and rehabilitation. Replace existing compression seals and block out style joints
in those locations where expansion or rotation is needed with strip seal style expansion
devices.
c) Establish a routine maintenance procedure to maintain joints.

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Scoring Criteria:
The points are awarded based on the requirement met as shown in Table 3.6

Table 3.6: Scoring Criteria for Bridge Deck Joints and Seals
Requirement
a
b
c

Points
2
1
1

Standards/Resources:
• “Evaluation of various types of bridge deck joints”, Final Report 510, Baker Engineering and
Energy, Arizona Department of Transportation

76

Criteria 3.8 Snow and Ice Control (1 Point)
Description:
Michigan is one of the states that get heavy snow in winters. The standard procedure to remove
snow or ice is by chemical treatment and plowing. Deicers are applied to roadway to break up
frozen precipitation provide traction and ease cleanup efforts. The most commonly used deicer in
Michigan is salt.

Intent:
To implement snow and ice control techniques to reduce associated impacts of snow and ice on
the bridge.

Requirements:
a) Implement snow and ice control plan including techniques to remove snow and ice from
bridges.
b) Implement management plan to monitor the quantity of deicer applied.
c) Applying appropriate treatments or putting sensors on the bridge in order to track weather
and bridge conditions. Currently MDOT uses weather stations on some bridges. By
monitoring air temperature anti-icing chemicals can be applied prior to storm events or frost.
As long as anti-icing agents are applied before the bridge deck freezes, deicing agents (such
as salt) will not have to be added immediately and the snow and ice do not bond to the deck
surface, making cleanup easier.
d) Anti-icing measures should take place before the snow falls and ice forms on the roadway.
Liquid form (brine) is generally used as anti-icing chemicals to road surfaces just before a

77

snow or ice storm. “Liquid sodium chloride (NaCl) is the most effective choice for anti-icing
above 15° F (-9.4° C)” (Salt Institute, 2011)
e) Pre-wetting is effective method of spraying deicing salt as it assist in spreading less salt,
saving money and minimizing the threat to the environment. Also wet salt clings to the road
instead of bouncing off or being swept off by traffic thereby saving the amount of salt.
Sodium chloride (salt) brine is a low-cost, effective alternative to liquid calcium chloride as a
pre-wetting agent (Donahey & Burkheimer, 1996).

Scoring Criteria:
1 point will be awarded for making a snow and ice control plan and using any one method to
implement the plan.

Standards/Resources:
•

Operation and Maintenance Criteria 9- Snow and Ice Control, Sustainable Highways SelfEvaluation Tool, FHWA, USDOT

78

3.3 Quantifying the Green Rating System
A Delphi Survey conducted by another member of the research group is used to assign weights
to category and point values to the criteria. The details of the survey can be found in the thesis
“Life Cycle Costs Analysis and Delphi Survey to Assist Sustainable Framework for Bridges in
Michigan” developed by Awan (2012). Based on the results of Delphi survey, scorecard for the
rating is developed which is shown in Table 3.7
Table 3.7: Scorecard for the Green Rating System
Scorecard
1. Design (47 Points)
Maximum

Criteria

Criteria Name

Criteria 1.1.1

Site Selection

6

Criteria 1.1.2

Historic Site Preservation

3

Criteria 1.1.3

Soil Erosion & Sedimentation Control

6

Criteria 1.1.4

Brownfield Redevelopment

2

Criteria 1.1.5

Storm-Water Management

5

Criteria 1.2.1

Use of Recycle Materials

5

Criteria 1.2.2

Supplemental Cementitious Materials

3

Criteria 1.2.3

Reduction in Quantity of Materials

3

Criteria 1.2.4

Material Reuse

2

Criteria 1.2.5

Regional Materials

3

Criteria 1.3.1

Renewable Energy Use

1

Criteria 1.3.2

Bicycle/ Pedestrian Pathways

2

Criteria 1.3.3

Lane Adaptability

1

Criteria 1.3.4

Life Cycle Cost Analysis

5

79

Available Points

Table 3.7 (cont’d)
Scorecard
2. Construction (31 Points)
Criteria

Criteria Name

Criteria 2.1

Accelerated Bridge Construction

Maximum
Available Points
14

Techniques
Criteria 2.2

Corrosion resistant steel reinforcement

8

Criteria 2.3

Efficient Water Use

2

Criteria 2.4

Non-road equipment emission reduction

2

Criteria 2.5

Construction Waste Management

4

Criteria 2.6

Use of Certified Wood

1

3. Maintenance (22 Points)
Maximum

Criteria

Criteria Name

Criteria 3.1

Efficient Inspection Technologies

3

Criteria 3.2

Bridge Painting/Coating

6

Criteria 3.3

Bridge Cleaning

2

Criteria 3.4

Bridge Deck Drainage

2

Criteria 3.5

Avoiding and Minimizing Impacts to

1

Available Points

Fish and Wild Life
Criteria 3.6

Corrosion Control Materials

3

Criteria 3.7

Bridge Deck Joints and Deck Joint Seals

4

Criteria 3.8

Snow and Ice Control

1

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3.4 Certification Levels
After assigning points to each criterion, the next step is to decide certification levels to categorize
sustainable bridges. The methodology for determining certification levels is shown in Table 3.8.
Each criterion is determined whether it is easy to implement, difficult to implement or has
medium level of difficulty in achieving the criteria. This was first determined by the discussion
of research panel. It was sent for further review to MDOT experts and the justification for its
level of difficulty to achieve has been then provided by MDOT. The sum of points of easy to
implement, medium to achieve and difficult to achieve were found.

81

Table 3.8: Certification Levels Determination
Criteria

Level of Implementation
Easy Medium Difficult
6

Criteria Name

Criteria
1.1.1
Criteria
1.1.2
Criteria
1.1.3
Criteria
1.1.4
Criteria
1.1.5
Criteria
1.2.1

Site Selection

Criteria
1.2.2
Criteria
1.2.3

Supplemental
Materials
Reduction in
Materials

Criteria
1.2.4
Criteria
1.2.5
Criteria
1.3.1

Renewable Energy Use

Historic Site Preservation

3

Soil Erosion & Sedimentation
Control
Brownfield Redevelopment

2

Storm-Water Management

2

Available
Points
6
3

4

6
2

3

2
5

Use of Recycle Materials

5

5

2

3

3

3

Material Reuse

2

2

Regional Materials

3

3

Cementitious
Quantity

1

of

1

1

82

Justification
Bridge designers normally do not have a
choice in site selection.
Required by MDOT
Requirements “a”, “b” & “c” are
required. BMP's are optional
Usually avoided. MDOT does not want
to assume liability
Requirement “a” is optional
FHWA requires new materials to be
used in all new constructions. Has been
mandated in some pilot projects as
backfill
Dictated by the mix design
Deflection req. limit the beam shape so
we can choose higher strengths but may
not be able to reduce cross section
Again, FHWA limit materials to new
Existing supplier may be outside the
500-mile radius. Contractor choice and
not MDOT's
This is considered and applied where
feasible

Table 3.8 (cont’d)
Criteria
1.3.2
Criteria
1.3.3

Bicycle/ Pedestrian Pathways
Lane Adaptability

1

1

Mandated to consider this in design but
not required to construct
Standard practice now

Criteria
1.3.4
Criteria 2.1

Life Cycle Cost Analysis

5

5

Standard practice now

Accelerated Bridge Construction
Techniques

3

5

14

SPMT work in Utah but so far unsuccessful
in MI. FHWA now mandates that 25% of
all bridges use ABCT

Criteria 2.2

Corrosion
resistant
reinforcement
Efficient Water Use

4

4

8

Epoxy coated rebar is required above
ground.
Gray water is not allowed in mix design so
this may be impossible to get.
Contractors choice

Criteria 2.3

steel

2

2

6

2

2

2

2

2

4

Criteria 2.5

Non-road equipment emission
reduction
Construction Waste Management

Criteria 2.6

Use of Certified Wood

Criteria 3.1

Efficient Inspection Technologies

Criteria 3.2

Bridge Painting/Coating

Criteria 3.3

Bridge Cleaning

Criteria 3.4

Bridge Deck Drainage

2

2

Required by MDOT

Criteria 3.5

Avoiding
and
Minimizing
Impacts to Fish and Wild Life
Corrosion Control Materials

1

1

Required by MDOT

3

Use of anodes is standard practice.

Criteria 2.4

Criteria 3.6

2

1

MDOT Spec 205.03P requires us to handle
all waste within right of way.
Not applicable

3

3

Standard practice now

3

6

Should receive 6 points if concrete beams
are used.

1

3

1

2

1

1

83

2

Table 3.8 (cont’d)
Criteria 3.7
Criteria 3.8
Total

Bridge Deck Joints and Deck
Joint Seals
Snow and Ice Control

2

2

4
1

1
33

31

36

84

Requirement “a” and “b” are MDOT policy.
Standard practice now

100

The score range are divided into in three major levels which are 0-33 which represents the lower
range, 34-64 which represents the middle range and 65-100 which represents the higher range.
The lower range and the higher range is further divided into two halves since some of the criteria
are easy to achieve and very basic component of every bridge design and construction project
and they are likely to achieve Certified level in every project as any project can easily obtain at
least 1 or 2 points therefore, the certified level is further relegated to non-green level. Similarly,
in order to achieve complete sustainability in bridge project, the total green level to further
upgraded to Evergreen level. The certification levels are shown in the Table 3.9.
Table 3.9: Certification Levels for Bridge Green Rating System
Certification Level
Non-Green
Certified
Green
Total Green
Evergreen

Score Range
0-16
17-34
35-64
65-82
82-100

85

CHAPTER 4
GHG EMISSIONS CALCULATION GUIDELINES BASED ON LCA METHODOLOGY

4.1 Introduction
The construction sector accounts for 131 Million metric tons of CO2 equivalents (EPA, 2009).
The transportation sector is one of the biggest contributors of Greenhouse Gas (GHG) emissions.
According to greenhouse report by Environmental Protection Agency (EPA), transportation
sector is responsible for 27% of GHG emissions in 2002 and is the second biggest contributor by
sector followed by Industrial sector, which is responsible for 32% of GHG emissions (EPA,
2008). Therefore, significant amount of GHG emissions are associated with the construction and
use of transportation infrastructure and this has led State Department of Transportation Agencies
to take the challenge of global climate change and investigate strategies that reduce the life cycle
GHG emissions associated with transportation infrastructure which involves the design,
construction and maintenance of bridges (Mukherjee & Cass, 2012).

California Environmental Protection Agency has already developed a greenhouse gas emission
inventory that provides the estimate of the amount of GHG emissions associated with the various
activities. The inventory includes estimation of various gas pollutants such as Carbon-dioxide
(CO2), Methane (CH4), Sulphur hexafluoride (SF6), Nitrous oxide (N2O) etc. (California EPA,
2012). This study propose guidelines to measure GHG emissions for bridge construction projects
with the aim to calculate the carbon footprint, defined as a composite measure of all GHG
emissions expressed as equivalents of carbon dioxide emissions, and to develop a tool that can be
used to estimate and benchmark carbon footprints for bridge construction projects. Cradle to

86

Gate LCA approach is taken into account to estimate the emissions from raw material
acquisition, manufacturing and construction phase of different bridges.

4.2 Goals and Objectives
The goal of this section is to develop an LCA framework, which include guidelines for
determining carbon footprint associated with various items in bridge construction projects that
can enable various transportation agencies to evaluate the framework and investigate various
strategies to reduce GHG emissions thus supporting sustainable decision-making. This would
allow them to consider such alternatives that reduce GHG emissions. The guidelines were
developed using the following objectives:

Objective 1 – Develop a construction inventory, which includes list of materials and equipment
that can be used in bridge projects.
To accomplish this objective, list of materials and equipment that can be used in bridge project
were collected using MDOT construction plans and specifications and from construction
inventory developed by Mukherjee & Cass (2011) for computing GHG emissions in highway
reconstruction and rehabilitation projects.

Objective 2 - Report estimated emission factors for all the materials and equipment.
Estimated emission factors were found out for the products based on literature review, reviewing
historical databases and using software tool “SimaPro”.

87

Objective 3 – Provide a tool to calculate the quantity of GHG emissions due to materials and
equipment used in the bridge project.
Excel based tool is developed to calculate the quantities of GHG emission from the products.
This tool is based on the web-based tool called project estimator developed by Mukherjee &
Cass (2011) for calculating GHG emission in highway reconstruction and rehabilitation projects.
This tool can be found at
http://www.construction.mtu.edu:8000/cass_reports/webpage/estimator.html.

Objective 4 – Conduct a case study and compare GHG emissions based considering two
alternatives.
A case study is conducted which include a MDOT bridge replacement project. This case study is
used to compare GHG emission for two alternative bridge decks – conventional concrete bridge
deck and the Fiber Reinforced Polymer (FRP) bridge deck.

4.3 Building Blocks for Developing GHG Emission Calculation Guidelines
The building blocks for developing GHG emission calculation guidelines shown in Figure 4.1
are research study “Carbon Footprint for HMA and HCC Pavements” most of the products and
emissions factors are obtained from product inventory developed in this study; literature and
historical databases as these are used to obtain emission factors of some of the products and
software tool “SimaPro” as emission factors are also obtained using this tool.

88

Literature Review

Historical Databases

Building Blocks for
Developing GHG
Emission Calculation
Guidelines

Previous Research Study "Carbon
Footprint for HMA and HCC
Pavements

Software Tool SimaPro

Figure 4.1: Building Blocks for Developing GHG Emission Calculation Guidelines

a) Carbon Footprint for HMA and HCC Pavements
Mukherjee and Cass (2011) conducted this research study and prepared a report for MDOT.
They proposed a project based life cycle assessment framework that can be used to estimate
GHG emissions of typical highway reconstruction and rehabilitation projects. The aim of the
research study is to calculate the carbon footprint of Hot Mix Asphalt (HMA) and Portland
Hot-Mix
Cement Concrete (PCC) pavements for both reconstruction and rehabilitation projects. The
objectives stated in the research study are:
a) Report construction inventories for 14 highway reconstruction, rehabilitation and Capital
ion
Preventive Maintenance (CPM) projects observed over a period of two summers
b) Report estimated emission factors for construction materials and equipment used
c) Report estimated emission factors for use phase of highways
d) Provide contractors a tool to benchmark construction and rehabilitation projects
89

e) Provide MDOT a tool to assess emissions through the different life cycle stages of a
pavement (Mukherjee & Cass, 2012)

State Agencies and contractors can use it to estimate GHG emissions for specific construction
operations. These can be used to investigate or identify alternative materials or improvements in
construction processes to reduce their emissions. In turn, this will encourage the adoption of low
emission products and techniques into practice, thus indirectly including other stakeholders such
as material suppliers and equipment manufacturers. The framework was developed using the
following steps:
Data Collection Phase:
In this phase, data were collected from fourteen different highway construction and maintenance
project sites in the state of Michigan to develop a comprehensive project inventory of materials
and equipment. These projects included HMA and concrete reconstruction, maintenance and
rehabilitation projects. The data were collected during the construction phase and use phase of
the pavement. The collection of this data was very important to know the materials, equipment
and processes involved to develop project inventory. Estimates of GHG emissions from these
products were calculated, taking advantage of the existing methods of calculating GHG
emissions. It accounts for emissions from the following stages:
a) Extraction of raw materials or mining;
b) Manufacturing and production of the products (materials and equipment used to construct the
pavement);
c) Off-road and On-road transportation of the products;
d) Processes involved during the construction and maintenance of the pavement

90

e) Service life (use-phase of the pavement)

Motor Vehicle Emission simulator (MOVES), which is a traffic simulation environment
developed by EPA, is used to estimate the use phase emissions due to on-road vehicular traffic.
Excess emissions due to traffic delays and reduced speeds in construction zones are also
considered.

Emission factors were collected from existing literature, historical databases to estimate the
emissions from these products. EPA defines emission factor as: “An emissions factor is a
representative value that attempts to relate the quantity of a pollutant released to the atmosphere
with an activity associated with the release of that pollutant. These factors are usually expressed
as the weight of pollutant divided by a unit weight, volume, distance, or duration of the activity
emitting the pollutant (e.g., kilograms of particulate emitted per mega-gram of coal burned).
Such factors facilitate estimation of emissions from various sources of air pollution. In most
cases, these factors are simply averages of all available data of acceptable quality, and are
generally assumed to be representative of long-term averages for all facilities in the source
category (i.e., a population average)” (EPA, 2011).

Once emission factor is developed for a product, emissions due to the product in a life cycle can
be calculated by multiplying the emission factor by its quantity. For example, if the emission
factor is .012 and 100 MT of asphaltic material is used in the project. Then emissions due to
asphaltic material will be .012 X 100 MT = 1.2 MT of CO2 i.e. CO2 equivalent emissions of
asphaltic materials will be 1.2 MT/100 MT of material. Similarly, emission factor for other

91

products can be developed and emissions can be calculated. Once the emissions from all the
products and process are calculated these can be summed up to calculate the total project
emissions.

Inventory Development:
The data that were collected through the fourteen projects were organized into material and
equipment categories to develop a project inventory. The inventory would consist of product and
processes, their emission factors and other details.

Analyzing the inventory and estimating project life cycle GHG emissions:
LCA techniques were used to assess the environmental impacts of the products and processes.
Economic Input Output Life-cycle Assessment (EIO-LCA) (Hendrickson et al. 1998, Cicas et al.
2007) is one of the many methods used to assess environmental impacts. The principal
investigator in this research study uses this method in his previous work to assess the
environmental impact associated with the products and processes.

Hybrid LCA Methodology:
There are two ways to conduct an LCA a) input-output based LCA, or b) a process based LCA.
Economic input-output based LCAs are based on economic transactions and resource
interactions between an exhaustive set of economic sectors. The Economic Input Output-Life
Cycle Assessment (EIO-LCA) is also used in the hybrid model. It is a model that defines the
scope and number of environmental effects quantified in a LCA, developed at Carnegie Mellon

92

University (Hendrickson , 2006). It estimates the economic contribution, resource requirements
and environmental emissions for a particular product, service, or activity.

In this study, in order to estimate the GHG for all materials and equipment inputs, an inputoutput and/or process LCA tool is used to take advantage of the most recent emission factors that
have been reported in the process LCA literature, when applicable, as well as maximize the
advantages of an input-output LCA. In the model, the GHG emissions are quantified as a
function of the construction and vehicle operations in terms of material/fuel usage.

The emission factors used in this study are from process LCAs reported in literature. They have
been taken primarily from the Stripple (Stripple, 2011), Athena (AETHNA, 2006) and NREL
(NREL) inventories. These emission factors are usually expressed as Tons of CO2 equivalents
per unit weight or volume. Therefore, given a bulk volume or weight of a material use on a
particular project, the emissions can be calculated by using the emission factors.

The proposed framework is based on process, product, service (PPS) method which includes
different process and product components. This approach uses existing calculation methods of
GHG emissions but uses the data collected through fourteen highway construction projects.

Product Components:
All the materials that are listed in department of transportation agency specification were
accounted for. Both virgin materials and recycled materials were taken into consideration and
were accounted for during the mining, manufacturing and transportation of the materials to and

93

from the site phases. All the equipment that are used in highway construction were taken into
consideration and accounted for emissions due to manufacturing, transportation, construction and

maintenance operations (Mukherjee & Cass, 2012). For each of these products, emission factors
were developed emissions can be calculated depending on the quantity of these products.

Process Components:
It includes two components - the processes on site that are directly involved in the highway
construction and maintenance operations, e.g., construction schedule and operation design; and
the processes that directly influence decisions of long-term pavement behavior, e.g.,
determination of maintenance schedules (Mukherjee & Cass, 2012).

Service life components:
Since, it can be difficult to estimate, a traffic simulation environment MOVES [35] was used to
estimate use phase emissions due to on-road vehicular traffic.

Implementation of web based tool to calculate GHG emissions of the products:
The Project estimator tool PE-2 is developed which is an easy to use interface to calculate GHG
emissions in a project. This tool can be accessed at
http://www.construction.mtu.edu:8000/cass_reports/webpage/estimator.html. The purpose of the
tool is:
1) Inventory Reporting:
User can query all relevant data collected and creates a report for the project.

94

2) Benchmarking and Estimating:
PE-2 tool can be used at the project level to estimate and benchmark emissions. To benchmark
expected project emissions, use the bill of materials and estimated material and equipment use in
the project. At the end of the project, use PE-2 to generate an emissions report using the actual
data collected. MDOT should encourage contractors (through direct economic or equivalent
incentive) to reduce the actual project emissions when compared to the benchmark for the
project. Incentive plan can be generated for the contractor’s efforts at reducing GHG emissions
during the project construction process. This could be through more efficient project site design
and schedule planning or using alternative materials during the construction process.

b) Literature and Historical Databases
Various historical databases are available to get emission factors for calculating life cycle GHG
emissions from products. National Renewable Energy Laboratory (NREL) has developed a life
cycle inventory database to assess life cycle impacts. NREL and its partners created the “U.S.
Life Cycle Inventory (LCI) database provides individual gate-to-gate, cradle-to-gate and cradleto-grave accounting of the energy and material flows into and out of the environment that are
associated with producing a material, component, or assembly in the U.S” (NREL, 2012).
Various other databases such as life cycle inventory of Portland concrete, life cycle inventory of
steel and other products were accessed to determine GHG emissions from those products.

Most of the emission factors in this study are adopted from the research report “Carbon Footprint
for HMA and HCC Pavements” developed by Amlan Mukherjee and Darrell Cass. Emission
factors of all the equipment are adopted from this report.

95

c) SimaPro
SimaPro is one of the LCA tool and is most widely used in the industry. SimaPro is used in this
study to calculate emission factor of some of the products that can be used on bridge projects.
Cradle to Gate LCA is performed using SimaPro according to International Standard ISO 14040
i.e. it includes all the four phases, which are described before. These are goal and scope
definition, life cycle inventory analysis, impact assessment and interpretation. Environmental
performance is generally measured in terms of a wide range of potential effects, such as
(Carmody & Trysty, 2005) Fossil fuel depletion, Other non-renewable resource use, Water use,
Global warming potential, Stratospheric ozone depletion , Ground level ozone (smog) creation,
Nutrification (excess nutrients)/eutrophication (oxygen deficiency) of water bodies ,
Acidification and acid deposition (dry and wet) , Toxic releases to air, water, and land.

All of these measures are indicators of the environmental loadings that can result from the
manufacture, use, and disposal of a product. SimaPro is used in this study to calculate total
cradle to gate CO2 equivalent releases of different products. The international standard
organization ISO 14040 and ISO 14044 has developed a framework and guideline on how to
conduct an LCA. SimaPro is organized according to ISO 14040 and ISO 14044 guidelines for
conducting LCA shown in Figure 4.2. The following steps are defined in conducting an LCA
(ISO 14040, 2006; ISO 14044, 2006):
a) Defining goal and scope of the study;
b) Development of an exhaustive inventory of all energy and material inputs, and the
environmental outputs and emissions associated with each life cycle phase;
c) Analysis of impacts of inputs and outputs identified in the inventory analysis on humans and

96

ecology, and;
d) Appropriate interpretation of the analysis to support policy and decision- making.

Figure 4.2: SimaPro Organization (The text is not meant to be readable, but for visual
reference only)

All the general decisions regarding the LCA study are defined in the goal and scope phase. The
reason for the study and the overall goal of the study is defined in this stage. The product
description and all the assumptions are also described. System boundaries, impact categories,
data quality, methodology are also described in the goal and scope definition phase. It also needs

97

to be decided that what is included and what is excluded from the product system and whether all
or part of the product life cycle is taken into the account.
In the Life Cycle Inventory (LCI) phase shown in Figure 4.3, all the processes are defined in
each life cycle phase and energy and material inputs and environmental emission outputs are
determined and included. The outputs can be air emissions, water pollutants, solid wastes and
other releases. The inputs and outputs can be determined through an exhaustive data collection
procedure. Quantitative and qualitative data for every process in the system can be collected
through site visits, commercially or publicly available databases or through the collection of
secondary data from literature. The LCI database list all the material and energy inputs and
outputs.

The LCI result allows calculating potential impacts of a product system on humans and ecology.
This impact assessment method is known as Life Cycle Impact Assessment (LCIA). There are
four steps in calculating LCIA, which are Classification, Characterization, Normalization and
Evaluation. The last two steps are optional. Each output is classified into one or more impact
categories. Impact categories can be Global Warming Potential (GWP), Fossil Depletion,
Freshwater Eutrophication, Ozone Depletion, and Terrestrial Acidification etc. Therefore, the
issue of Global Warming is represented by the GWP category. Any emission to air that
contributes to global warming is classified as contributors to GWP. The quantity of each of these
pollutants is then converted to quantity of eq. CO2 by multiplying their quantities by a
characterization factor (these factors are determined by different scientific groups and different
methodologies, most commonly impact category methodology is Tools for the Reduction and
Assessment of Chemical and other Environmental Impacts (TRACI) (EPA, 2012) in USA) to

98

determine their CO2 equivalent if eq. CO2 is the reference unit of the impact category. The total
quantity of CO2 equivalent can be calculated for the impact category. This study is focused on
determining the GHG emissions in terms of CO2 equivalent thus determining the GWP of the
product system.

99

Systems: Only inputs from
nature and emissions

Unit Processes: Also includes sub
process in addition to inputs from
nature and emissions

Unit and
Quantity

Figure 4.3: LCI Phase (The text is not meant to be readable, but for visual reference only)

100

The last step, which is interpretation of the results shown in Figure 4.4 and Figure 4.5, has great
significance as it can be used to determine the environmental hotspots and conclusions. These
can be used to support policy and decision-making. Figure 4.6 to Figure 4.13 and Table 4.1
shows the results obtained from SimaPro. It shows cradle to gate CO2 eq. emissions from
different products. Table 4.2 list emission factors of all the materials.

Figure 4.4: Impact Assessment Phase (The text is not meant to be readable, but for visual
reference only)

101

Figure 4.5: Impact Assessment Phase (The text is not meant to be readable, but for visual reference only)

102

Label

Portland cement, at plant/US
1000
900
800

Transport, train, diesel
powered/US

kg CO2 eq

700
600

Transport, ocean freighter,
residual fuel oil powered/US

500
400
300

Transport, ocean freighter,
diesel powered/US

200
100

Transport, ocean freighter,
average fuel mix/US

0
1
Analyzing 1 ton 'Portland cement,
at plant/US';
Method: ReCiPe Midpoint (H) V1.05 / World
ReCiPe H / Characterization

Transport, combination truck,
diesel powered/US

Figure 4.6: Cradle to Gate Analysis of 1-Ton Portland Cement (Pre-Consultants, 2012)

103

Label
450
400

Carbon dioxide, fossil

kg CO2 eq

350
300

Carbon dioxide, fossil

250
Carbon dioxide, fossil

200
150

Methane, fossil

100
50

Methane, fossil

0
1

Dinitrogen monoxide
Analyzing 1 ton 'Blast furnace slag cement, at plant/CH
with US electricity U';
Method: ReCiPe Midpoint (H) V1.04 / Worl
ReCiPe H / Characterization

Sulfur hexafluoride
Dinitrogen monoxide

Figure 4.7: Cradle to Gate Analysis of 1-Ton Blast Furnace Slag Cement (Pre-Consultants,
2012)

104

Label

100

kg CO2 eq

120

Carbon dioxide, fossil

80

Carbon dioxide, fossil

60

Carbon dioxide, fossil

40

Methane, fossil

20
Dinitrogen monoxide
0
1

Methane, fossil

Analyzing 1 ton 'Concrete block,
at plant/DE U';
Method: ReCiPe Midpoint (H) V1.04 / World
ReCiPe H / Characterization

Methane, tetrafluoro-, CFC14
Dinitrogen monoxide

Figure 4.8: Cradle to Gate Analysis of 1-Ton Concrete Block (Pre-Consultants, 2012)

105

100
Label

90
80

Carbon dioxide, fossil

kg CO2 eq

70
60

Carbon dioxide, fossil

50
40

Carbon dioxide, fossil

30
20

Methane, fossil

10
0

Dinitrogen monoxide

1

Methane, fossil
Analyzing 1 ton 'Sand-lime brick,
at plant/DE U';
Method: ReCiPe Midpoint (H) V1.04 /
World ReCiPe H / Characterization

Dinitrogen monoxide
Dinitrogen monoxide

Figure 4.9: Cradle to Gate Analysis of 1-Ton Sand-Lime Brick (Pre-Consultants,
2012)

106

2500

Label

2000

Carbon dioxide, land
transformation
Methane

kg CO2 eq

Dinitrogen monoxide
1500

Ethane, 1,2-dichloro-1,1,2,2tetrafluoro-, CFC-114
Methane, trichlorofluoro-,
CFC-11
Methane, dichlorodifluoro-,
CFC-12
Methane, chlorotrifluoro-,
CFC-13
Methane, chlorodifluoro-,
HCFC-22
Methane, tetrafluoro-, CFC14
Sulfur hexafluoride

1000

500

0
1

Methane, dichloro-, HCC-30
Analyzing 1 ton 'Polypropylene fibres (PP), crude oil based,
production mix, at plant, PP granulate without additives EU-27 S';
Method: ReCiPe Midpoint (H) V1.04 / World ReCiPe H /
Characterization

Figure 4.10: Cradle to Gate Analysis of 1–Ton Polypropylene Fibers (Pre-Consultants,
2012)

107

140
Label
120

kg CO2 eq

100

Carbon dioxide, fossil

80

Carbon dioxide, fossil

60
Carbon dioxide, fossil
40
Methane, fossil

20
0

Dinitrogen monoxide
1
Analyzing 1 ton 'Light clay brick, at
plant/DE U';
Method: ReCiPe Midpoint (H) V1.04 / World
ReCiPe H / Characterization

Dinitrogen monoxide

Figure 4.11: Cradle to Gate Analysis of 1-Ton Light Clay Brick (Pre-Consultants, 2012)

108

3000
Label
2500

kg CO2 eq

Carbon dioxide, fossil
2000
Methane, fossil

1500
1000

Carbon dioxide, fossil

500

Carbon dioxide, fossil

0

Dinitrogen monoxide

1

Methane, fossil

Analyzing 1 ton 'Latex, at plant/RER
with US electricity U';
Method: ReCiPe Midpoint (H) V1.04 /
World ReCiPe H / Characterization

Methane, biogenic
Hydrocarbons, chlorinated

Figure 4.12: Cradle to Gate Analysis of 1-Ton Latex (Pre-Consultants, 2012)

109

1.4
Label

kg CO2 eq

1.2
1

Carbon dioxide

0.8
0.6

Methane

0.4
0.2

Methane, chlorodifluoro-,
HCFC-22

0
1
Analyzing 1 USD 'Plastics materials and resins';
Method: ReCiPe Midpoint (H) V1.04 /
World ReCiPe H / Characterization

Methane, tetrachloro-,
CFC-10
Dinitrogen monoxide

Figure 4.13: Cradle to Gate Analysis of 1-Ton Plastic Materials and Resins (PreConsultants, 2012)

Table 4.1: Emission Factors Obtained Using SimaPro (Pre-Consultants, 2012)
Product

Unit

Emission Factor (MT eq. CO2)

Portland Cement

Ton

.928

Blast Furnace Slag Cement

Ton

.522

Concrete Block

Ton

.121

Sand Lime Brick

Ton

.13

Polypropylene Fibers

Ton

2.33

Light Clay Bricks

Ton

.161

Latex

Ton

2.63

Plastics and Resins

Ton

.00168

Portland Slag Cement

Ton

.776

110

4.4 GHG Emissions Calculation Guidelines
In order to develop LCA guidelines for the bridges, the framework described above can directly
be used. The following steps can be followed for conducting LCA of bridges and determining the
carbon footprint:
a) Use bill of materials to determine all the materials to be used on the project. Also determine
all the construction equipment to be used, their number and estimated hours of usage.
b) Use the emissions estimating tool (refer to the format. xlsx) to calculate the emission from
the products. This tool is based on Project Estimator Tool PE-2, which can be found at
http://www.construction.mtu.edu:8000/cass_reports/webpage/estimator.html (Mukherjee &
Cass, 2012) to determine life cycle GHG emissions (Cradle to Gate) associated with the
materials and equipment to create benchmark emissions of the project.

The excel file has two sheets. Material emission estimator calculates the emission from
materials and Equipment emission estimator calculates the emissions from the equipment.
The material and equipment categories were organized according to MDOT pay-item
specifications. A separate category “Other” is also included in the Material emissions
estimator, which list the recommended sustainable products from the framework.

Use material estimator show in Table 4.2 for calculating GHG emissions from various
materials. Input the quantity of materials corresponding the material selected to determine
emissions from that material.

111

Use equipment estimator from the project estimator tool developed by Mukherjee & Cass
(2011) for calculating GHG emissions from various equipment. It is required to enter the
number of equipment and the estimated hours of usage of the equipment corresponding to
the equipment of selected to calculate GHG emissions from that equipment. All the
emissions will sum up which will be the benchmark emissions for the project. At the end of
the project, use emission estimator tool to generate an emissions report using the actual data
collected. MDOT should encourage contractors (through direct economic or equivalent
incentive) to reduce the actual project emissions when compared to the benchmark for the
project (Mukherjee & Cass, 2012). Investigate strategies to identify alternative products and
processes to reduce GHG emissions of products, which have higher GHG emissions.
Determine all the recommended solution and alternative products that can be used on the
project.Calculate the GHG emissions of all the final products that will be used and know the
carbon footprint of the sustainable bridge project. Table 4.3 is a material estimator which
calculates the cradle to gate emissions from materials. The sum of emissions in the last row
is the emission due to unit quantity of all the materials.

112

Table 4.2: Material Estimator

Cradle to Gate Emissions

Material

Unit

Quantity

Emission Factor

Section 901 (Cement and Lime)
1
0.928
1
0.0177

Emissions (MT CO2
Eq.)

Remarks/Details

0.928
0.0177

(Pre-Consultants, 2012)
(Mukherjee & Cass,
2011)
(Pre-Consultants, 2012)

Portland Cement
Fly Ash

Ton
Ton

Blast Furnace Slag Cement

Ton

Natural Aggregates

Ton

Aggregates 21A

Ton

1

0.0061

0.0061

Aggregates 21AA

Ton

1

0.0061

0.0061

Aggregates 21AA Crushed Concrete

Ton

1

0.0021

0.0021

Aggregates 22A

Ton

1

0.0061

0.0061

Aggregates 22A Crushed Concrete

Ton

1

0.0021

0.0021

Aggregates 22A (For Temp Use
Only)

Ton

1

0.0061

0.0061

1
0.522
Section 902 (Aggregates)
1
0.0061

113

0.522
0.0061

(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)

Table 4.2 (cont’d)
Aggregates 23A

Ton

1

0.0061

0.0061

(Mukherjee & Cass,
2011)

Material

Unit

Quantity

Emission Factor

Emissions (MT CO2
Eq.)

Remarks/Details

Aggregates 23A Carol Pit 11-077

Ton

1

0.0061

0.0061

Aggregates 23A (For Temp Use
Only)
Aggregates 23A (Reed Pit A 11-085)

Ton

1

0.0061

0.0061

Ton

1

0.0061

0.0061

Aggregates 25A

Ton

1

0.0061

0.0061

Aggregates 29A

Ton

1

0.0061

0.0061

Aggregates 2FA

Ton

1

0.0061

0.0061

Aggregates 34R

Ton

1

0.0061

0.0061

Aggregates 3FA

Ton

1

0.0061

0.0061

Aggregates 4G

Ton

1

0.0061

0.0061

Aggregates 4G Modified Crushed
Concrete
Aggregates 4G Modified Limestone

Ton

1

0.0021

0.0021

Ton

1

0.0061

0.0061

Aggregate 6A

Ton

1

0.0061

0.0061

Aggregate Coarse CS-2

Ton

1

0.0061

0.0061

(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)

114

Table 4.2 (cont’d)
Fine Aggregate 2fa

Ton

1

0.0061

0.0061

Fine Aggregate 2FA

Ton

1

0.0061

0.0061

Flowable Fill

Cyd

1

0.0001

0.0001

Granular Material

Cyd

1

0.0001

0.0001

Granular Material CL II

Cyd

1

0.0001

0.0001

Material

Unit

Quantity

Emission Factor

Emissions (MT CO2
Eq.)

Remarks/Details

Granular Material CL III

Cyd

1

0.0001

0.0001

Granular Material CL IIIA

Cyd

1

0.0001

0.0001

Granular Material CL II Modified

Cyd

1

0.0001

0.0001

Granular Material CL II Newark

Cyd

1

0.0001

0.0001

Granular Material CL Tri City

Cyd

1

0.0001

0.0001

Granular Material CL (Ton)

Ton

1

0.00006

0.00006

Pulverized HMA

Ton

1

0.0049

0.0049

Sound Class II (D) for Underdrain

Cyd

1

0.0001

0.0001

Sound earth

Cyd

1

0.0001

0.0001

(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)

115

(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)

Table 4.2 (cont’d)

White Membrane Curing
Compound for Bridge Decks
Non-Chloride Accelerator

Section 903 (Admixtures and Curing Materials for Concrete)
Gal
1
0.01255
0.01255
Cft

1

NanoMT

Latex Admixtures
Polypropylene Fibers

Ton
Ton

Asphalt Binder PG 58-28

Ton

Emulsified Asphalt

Gal

1

0.0071

0.0071

Material

Unit

Quantity

Emission Factor

Emissions (MT CO2
Eq.)

Remarks/Details

Emulsified Asphalt CSS-1hM

Gal

1

0.0071

0.0071

Ashpalt emulsion Chip Seal

Gal

1

0.0071

0.0071

Asphalt Emulsion CSS-1hM

Gal

1

0.0071

0.0071

Asphalt Emulsion CSS-1mM

Gal

1

0.0071

0.0071

Asphalt Emulsion HFRS-2M

Gal

1

0.0071

0.0071

Asphalt Emulsion RC-250

Gal

1

0.0071

0.0071

(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)

Dowel Bar

Ea

1
2.63
1
2.33
Section 904 (Asphaltic Materials)
1
0.1569

NanoMT

Section 905 (Steel Reinforcement)
1
0.001627

116

2.63
2.33

(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Pre-Consultants, 2012)
(Pre-Consultants, 2012)

0.1569

0.001627

(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)

(Mukherjee & Cass,
2011)

Table 4.2 (cont’d)
Dowel Bar Epoxy Coated

Ea

1

0.001627

0.001627

Steel Reinforcement

Lbs

1

0.0003

0.0003

Steel Reinforcement Epoxy Coated

Lbs

1

0.0003

0.0003

Lane Ties Epoxy Coated

Ea

1

0.01512

0.01512

Load Transfer Device

Ft

1

0.006

0.006

Steel Reinforcement Cable BarrierC Slagter

Lbs

1

0.003

0.003

Section 906 (Structural Steel)
1
0.0016

Steel Sections

Ton

Hot Rolled-Coil Steel

Ton

1

0.002

0.002

Material

Unit

Quantity

Emission Factor

Emissions (MT CO2
Eq.)

Remarks/Details

Hot-Dip Galvanized Steel

Ton

1

0.0025

0.0025

Steel Sheet Piling

Sft

1

0.0589

0.0589

Beam Plate Sealant Sherwin Wili
1550A
Guardrail Anchorage Bridge

Tube

1

0

0

Ea

1

0

0

Structural Steel

Cft

1

NanoMT

1

(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)

117

0.0016

(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)

Table 4.2 (cont’d)
Structural Steel Pin and Hangers

Cft

1

0

Barbed Wire

Cft

Fence Chain Link (ft)

Ft

1

0.0092

0.0092

Fence Gate Chain Link

Cft

1

NanoMT

NanoMT

Fence Post Chain Link Corner

Ea

1

0.0722

0.0722

Fence Post Chain Link Line

Ea

1

0.0722

0.0722

Fence Post Steel

Ea

1

0.0722

0.0722

Fence Post Steel Woven Wire

Ea

1

0.0722

0.0722

Fence Post Wood

Ea

1

0.0066

0.0066

Protective Fence

Ft

1

0

0

Fence Woven Wire

Ft

1

0.0092

0.0092

Section 907 (Fencing Materials)
1
NanoMT

118

0

(Mukherjee & Cass,
2011)

NanoMT

(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)

Table 4.2 (cont’d)

Material

Anchor Bolts

Unit

Quantity

Emission Factor

Emissions (MT CO2
Eq.)

Section 908 (Miscellaneous Metal Products)
Cft
1
NanoMT

NanoMT

Bushings

Ea

1

0

0

Steel Beam Guardrail

Ft

1

0.0656

0.0656

Gaurdrail Approach Terminal 1 B

Cft

1

NanoMT

NanoMT

Gaurdrail Approach Terminal 1 T

Ea

1

0

0

Gaurdrail Approach Terminal 2 B

Cft

1

NanoMT

NanoMT

Gaurdrail Approach Terminal 2 T

Cft

1

NanoMT

NanoMT

Gaurdrail Reflectorized Washers

Ea

1

0

0

Sleeve Steel

Ea

1

0

0

End Section Concrete

Ea

End Section Metal

Ea

1

1.1995

1.1995

End Section Grate

Lbs

1

0.0003

0.0003

Pipe Cl A

Ft

1

0.1464

0.1464

Section 909 (Drainage Products)
1
0.802

119

0.802

Remarks/Details

(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)

Table 4.2 (cont’d)
Pipe Cl E

Ft

1

0.1464

0.1464

Pipe Concrete

Ft

1

0.0663

0.0663

Material

Unit

Quantity

Emission Factor

Emissions (MT CO2
Eq.)

Remarks/Details

Pipe Steel

Ft

1

0.1464

0.1464

Pipe Plastic

Ft

1

0.0259

0.0259

Pipe RCP

Ft

1

0.0663

0.0663

Pipe Perforated Underdrain

Ft

1

0.0004

0.0004

Pipe Non-Perforated Underdrain

Ft

1

0.0004

0.0004

Pipe Corrugated

Ft

1

0.0259

0.0259

Expansion Joint Device

Ea

1

0

0

(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)

Biaxial Geogrid

Syd

Geotextile Blanket

Syd

1

0.0013

0.0013

Geotextile Liner

Syd

1

0.0013

0.0013

Geotextile Separator

Syd

1

0.0013

0.0013

Section 910 (Geo-synthetics)
1
0.0013

Section 912 (Timber and Lumber)

120

0.0013

(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)

(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)

Table 4.2 (cont’d)
Guardrail Post Wood

Cft

1

NanoMT

NanoMT

Wood Post

Cft

1

NanoMT

NanoMT

Post Wood Guard

Cft

1

NanoMT

NanoMT

(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)

Section 913 (Masonry Units)
Material

Unit

Quantity

Emission Factor

Emissions (MT CO2
Eq.)

Remarks/Details

Clay Brick
Concrete Brick

Ton
Ea

1
1

0.161
0.0014

0.161
0.0014

(Pre-Consultants, 2012)
(Mukherjee & Cass,
2011)
(Pre-Consultants, 2012)
(Pre-Consultants, 2012)

Concrete Block
Sand Lime Brick
Fiber Joint Filler

Ton
1
0.121
0.121
Ton
1
0.13
0.13
Section 914 (Joint and Waterproofing Materials)
Sft
1
0.0015
0.0015

Hot Poured Joint Sealant

Lbs

1

0.0006

0.0006

Foam Backer Road

Ft

1

0.0001

0.0001

1

Epoxy Resin Adhesive
Waterproofing Membrane
Preformed
Cobblestone
Fabric

Syd

1

1

0.0094

0.0094

Section 916 (Erosion and Sedimentation Control Materials)
Syd
1
0.0172
0.0172
Cft

1

NanoMT

121

1

(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)

Table 4.2 (cont’d)
Plain Rip Rap

Syd

1

0.0172

0.0172

Silt Fence

Ft

1

0.0008

0.0008

Fertilizer Chemical Nutrient

Section 917 (Turf and Landscaping Materials)
Lbs
1
0.0008
0.0008

(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)

Mulch

Ton

1

0

0

Material

Unit

Quantity

Emission Factor

Emissions (MT CO2
Eq.)

Remarks/Details

Mulch Blanket

Syd

1

0.0008

0.0008

Mulch Tackifier

Gal

1

0

0

Seeding

Lbs

1

0.001

0.001

Seeding Mixture

Lbs

1

0.001

0.001

Sod

Cft

1

NanoMT

NanoMT

Tack

Gal

1

0

0

Tackifier

Gal

1

0

0

Topsoil 4in.

Cft

1

NanoMT

NanoMT

Turf Reinforcement Mat

Syd

1

0.0008

0.0008

(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)

Section 918 (Electrical and Lighting Materials)

122

Table 4.2 (cont’d)
Conduit

Cft

1

NanoMT

NanoMT

High Intensity Light

Ea

1

0

0

Reflective Sheeting Material

Section 919 (Permanent Traffic Sign and Support Materials)
Cft
1
NanoMT
NanoMT

Dileneator Reflector

Cft

1

NanoMT

NanoMT

Temporary sign

Sft

1

0

0

Sign Cover

Ea

1

0

0

Pavement Marking Glass Beads

Section 920 (Permanent Pavement Marking Materials)
Lbs
1
0.0004
0.0004

Pavement Marking Poly BlendGlass Beads
Pavement Marking Polyurea

Lbs

1

0.0004

0.0004

Gal

1

0.059

0.059

Pavement Marking Polyurea White

Lbs

1

0.0071

0.0071

Pavement Marking Polyurea Yellow

Lbs

1

0.0071

0.0071

Reflective Marker

Cft

1

NanoMT

NanoMT

Thermoplastic

Lbs

1

0.0071

0.0071

123

(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)

Table 4.2 (cont’d)
Concrete Barrier Temporary

Ea

1

0

0

Drum Plastic

Ea

1

0

0

Stainless Steel
Plastic Materials and Resins
Portland Slag Cement
Precast Concrete (Mix 1)
Precast Concrete (Mix 2)

Ton
USD
Ton
Ton
Ton

1
1
1
1
1

Other Products
0.00151
0.00168
0.776
0.49
0.43

Sum of Emissions

124

0.00151
0.00168
0.776
0.49
0.43

(Mukherjee & Cass,
2011)
(Mukherjee & Cass,
2011)
(ISSF, 2010)
(Pre-Consultants, 2012)
(Pre-Consultants, 2012)
(Marceau et. al., 2007)
(Marceau et. al., 2007)

4.5 Case Study
4.5.1 Overview
GHG emission tool developed in the study can be used to compare different alternatives and
choose the best one which has the lower GHG emissions. MDOT provided the research team
with bidding documents and data on different bridges in Michigan, to calculate GHG emissions
from the products and find out the best alternative for the bridge superstructure. These bridges
either require repair/ rehabilitation or replacement.

GHG emissions were calculated from

alternatives on a concrete bridge to evaluate the sustainability of superstructure. This case study
compares two bridge decks one using conventional concrete bridge deck and the other using
Fiber Reinforced Polymer (FRP) bridge deck.

4.5.2 Structure Description
The structure considered is located on I-96 EB over Grange Road in Clinton County, 3.5 miles
southeast of Ionia. The bridge needs superstructure replacement. The structure must be able to
carry the loads prescribed in AASHTO HS-20 specifications, and it must last at least 75 years.
The further details of the structure were found in Table 4.3 using National Bridge Inventory
(NBI) website (NBI, 2012).

125

Table 4.3: Case Study-Bridge Structure Details
Description
NBI Structure Number
Route Sign Prefix
Year Built
Record Type
Service On Bridge
Service Under Bridge
Latitude
Longitude
Material Design
Design Construction
Structure Length
Approach
Roadway
Width
Lanes on Structure
Average Daily Traffic
Year of Average Daily
Traffic
# of Spans in Main
Structure
Structural Evaluation
Sufficiency Rating

Details
0000000000001789
Interstate
2007
Roadway is carried ON the
structure
Highway
Highway, with or without
pedestrian
42 48 47.16 N
84 47 18.90 W
Pre-stressed concrete
Stringer/ Multi-beam or Girders
37.5 m
13.4 m
2
19469
2007
3
Better than present mini criteria
95.2 %

4.5.3 Design Alternatives
This case study considered two alternatives: Table 4.4 below shows a comparison between
conventional concrete mix and alternative blast furnace slag cement concrete mix.
Table 4.4: Case Study-Design Alternatives
Alternatives
Base
Case:
Conventional
Concrete Mix Bridge Deck

Alternative Case:
Fiber Reinforced
(FRP) Bridge Deck

Details
Concrete Bridge Deck
Concrete Mix Ratio 1:2:4

FRP Bridge Deck
Composition: Glass Fibers
Epoxy Resins

Polymer

126

4.5.4 Methodology
Two stages are considered in the study:
(a) Demolition of the existing bridge superstructure
(b) Construction

Within each stage, three sources of carbon emissions are considered:
(a) Embodied carbon of any new materials/products
(b) Transportation of waste to landfills and transportation of products to site
(c) Traffic diversions

4.5.5 GHG Emission Calculation
1. Cradle to Gate GHG Emission due to Materials/Products
Table 4.5: Case Study: GHG Emission from Materials

Portland Cement

(Conventional Concrete Bridge Deck)
Unit
Quantity
Emission Factor
(MT CO2
Eq./Unit)
Ton
.928

Aggregates

Ton

.0061

Reinforcement
Steel

Lbs.

.0003

Material

(FRP Bridge Deck)
Epoxy Resin
GRP
Asphalt

127

Emissions
(MT CO2
Eq.)

2. Emissions due to transportation of waste to landfills and transportation of new products
a) Emissions due to transportation of waste to landfills
Table 4.6: Case Study: GHG Emissions from Transportation
Material

Unit

Type of
Transport

Transportation
Distance

Emissions

b) Emissions due to transportation of products to site
Table 4.7: Case Study: GHG Emissions from Transportation
Material

Unit

Type of
Transportation
Transport
Distance
Concrete Bridge Deck

Cement
Aggregates
Reinforcement
steel
FRP Bridge Deck
FRP Deck
Panel

128

Emissions

3) Emissions due to traffic diversions
Table 4.8: Case Study: GHG Emissions from Diversion
Type of
Construction
Convention

Period of
Disruption

Length of
Diversion

Average Daily
Traffic Volume
19469

Emissions

Concrete Bridge
Deck
19469

FRP Bridge Deck
Construction

4.5.6 Results
The emissions due to material are calculated based on emission factor method as shown in Table
4.7. The emissions can be obtained by multiplying the quantity of materials by the emission
factor. The emissions due to transportation can be calculated by knowing the transportation
distance of landfill from the site, type of transport and the total distance travelled. It is required
to determine the emissions due to vehicle travelling unit distance. The emission due to
transportation can then calculated by multiplying the total distance travelled by unit value of
carbon emissions. Emissions due to diversion of traffic can be calculated as Length of diversion
X Avg. daily traffic volume X Unit value of carbon emissions X Period of disruption from
vehicles. EPA’s MOVES (Motor Vehicle Emission Simulator) (EPA, 2012) can be used to
estimate unit value of carbon emissions from vehicles.

4.6 LCA Matrix for the Framework
The LCA matrix shown Figure 4.14 to 4.18 shows that which criteria in the framework is
impacted by LCA and which tools or metrics can be used to assess the environmental impacts

129

due to that criteria. The criteria of the framework can be evaluated using LCA matrix to
ia
evaluated
determine the impact of each criteria. The factor that each value represent is shown in Table 4.11

20

15

10

5
Sustainabil…
Sustainabil
Metrics/Tools

0

Impacted…

Impacted by LCA

Metrics/Tools

Sustainability Criteria

Figure 4.14 Design-Sites Category LCA Matrix
4.14:
Table 4.9 LCA Matrix Legend
4.9:

Impacted by LCA
Metrics/Tools
Sustainability Criteria

5
impacted

Not
LCA
NA
Economic

10
by Impacted by LCA
SimaPro
Social

130

15
NA
Excel based tool
Environmental

16
14
12
10
8
6
4
2
0

Sustainability Criteria
Metrics/Tools
Impacted by LCA

Impacted by LCA

Metrics/Tools

Sustainability Criteria

Figure 4.15: Design-Materials Category LCA Matrix
:

15
10
5
0

Sustainability Criteria
Metrics/Tools
Impacted by LCA

Impacted by LCA

Metrics/Tools

Sustainability Criteria

Figure 4.16 Design-Other Category LCA Matrix
4.16:

131

16
14
12
10
8
6
4
2
0

Sustainability Criteria
Metrics/Tools
Impacted by LCA

Impacted by LCA

Metrics/Tools

Sustainability Criteria

Figure 4.17 Construction Category LCA Matrix
4.17:

15
10
5
0

Sustainability Criteria
Metrics/Tools
Impacted by LCA

Impacted by LCA

Metrics/Tools

Sustainability Criteria

Figure 4.18 Maintenance Category LCA Matrix
4.18:

132

CHAPTER 5
RESULTS/CONCLUSIONS/LIMITATIONS AND RECOMMENDATIONS FOR
FUTURE WORK

5.1 Results and Conclusions
The focus of this report was to develop a framework that will assist transportation engineers and
managers develop more sustainable design and construction processes for new bridges, and
sustainable maintenance practices for existing bridges. As a result of this study, following results
were obtained:
a) Sustainable practices were synthesized which can be used in bridge construction projects.
b) A framework is developed to implement sustainable strategies in bridge projects. The
framework includes a Green rating system, which is divided into three major categories,
Design, Construction, and Maintenance. The details of the design category can be found in
MS thesis completed by Awan (2012), which is based on the research work for MDOT titled
as “Implementation of Sustainability in Bridge Design, Construction and Maintenance
(MDOT, 2012). The construction and maintenance sections are further divided into various
criteria. For each criterion the description, intent, and requirements have been established.
c) A scorecard for the rating system is developed based on the results of the Delphi Survey
conducted by Awan (2012) at MDOT divisions. It is found that Design category carries 47%
weightage, construction category carries 31% weightage and maintenance category carries
22% weightage.
d) Certification levels are developed to categorize sustainable bridges. The certification levels
are Non-Green, Certified, Green, Total Green and Evergreen. The score range for these
certification levels are 0-16, 17-34, 35-64, 65-82 and 83-100 respectively.
133

e) Guidelines were developed to estimate cradle to gate GHG emissions from materials and
GHG emissions from construction equipment in the use phase and can be used to evaluate
the framework.
f) Excel based tool is developed which consist of material estimator to compute GHG
emissions from materials and equipment estimator to compute GHG emissions from
equipment.

5.2 Research Limitations
a) The research uses the term green and sustainable interchangeably.
b) The research study mainly focuses on environmental sustainability.
c) The framework developed is mostly related to the bridges in Michigan as feedback is taken
only from Michigan Department of Transportation. However, the framework can also be
used by other DOT by modifying the framework or requirements of the criteria to meet their
own conditions and needs.
d) Life cycle Assessment methodology is focused to assess global warming impact potential and
ignores other impact categories.
e) Survey results are used to quantify the rating system and do not use scientific LCA approach.
f) Estimated emission factors may have been taken using old databases and records.

5.3 Recommendations for the Future Work
1. Framework can be updated based on different requirements.
This framework has been developed based on feedback from MDOT. Some of the criteria like
snow and ice control may not be required for other DOT, therefore that criteria can be excluded

134

from the framework. Similarly, other criteria may be included in the framework. Requirements
of criteria can also be modified by other DOT to meet their own conditions and needs.

2. Quantify the rating system using scientific LCA approach.
In this study, the survey results were used to quantify the rating system i.e. assigning point
values to all the criteria. In this study, case studies were not used to perform complete LCA of
bridges due to lack of time and data availability constraints. With the use of LCA software, it is
required to add each process associated with each life cycle stage. It is also required to enter
inputs and outputs for each process. This requires large collection of data. This is very time
consuming process and also due to data availability constraints complete LCA was not
performed to quantify the rating system. It is recommended to use LCA approach to quantify the
rating system. For this it is required to conduct 3-4 bridge case studies and perform a complete
LCA of those bridges. Then, it is required to assess the overall relative environmental impact of
each criterion of the framework on the environment. This will help in assessing the overall
impact of each criterion across all the impact categories. Then the points should be distributed to
the criteria according to the overall impact they have on the environment.

3. Apply the rating system on 20-30 bridges and adjust the certification levels.
It is possible that most of the bridges may easily achieve the green certification level or most of
the bridges may not achieve it. Therefore it is recommended to apply the rating system on 20-30
different bridges and adjust the certification levels. In this study, rating system was not applied
on 20-30 different bridge case studies as due lack of time and data availability constraints.
Methodology for determining certification levels used in GreenLITES rating system for

135

highways developed by NYSDOT can be used. In order to set a baseline, statistical thresholds
can established for each certification level (by standard deviation from the mean). Certification
levels can be determined by dividing all project scores into thirds representing low, middle, and
high levels of environmental sustainability. The lower third of all projects did not receive
certification, the middle third are Certified, and the upper third can be further subdivided into
Green, Total Green, and Evergreen, with progressively increasing requirements for attainment to
each successive level (NYSDOT, 2008).

136

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137

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