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I 4114;111:st g: 4: :5 .1 W HM "{ ‘3 *1 *32’.’ My min ‘ "‘ i 3 ! g 2.; up“: g F. {1:53; a; g; 2?; z-EEE: ' 21*! if, ”I *8" figagzzgigz; £é¥fi§é¢ Fir lgi- . i(! :7" “I “1‘::l.;§‘*:.:l25ii‘§‘j?i f ‘,;Lz-.‘.?ze§*;r}!:%uf*‘3 2:? 3mg; E' mess lllllllllllllllllllUllllllllllllllllllllllllllllllllllllll Q 31293 02050 9703 4 r ’" r'\ J V, MR 19*.— Menage Unwe This is to certify that the dissertation entitled AN EVALUATION OF THE IMPACTS OF CHANGEABLE MESSAGE SIGNS ON FREEWAY DIVERSION presented by Bellandra Benefield Foster has been accepted towards fulfillment of the requirements for Ph. D. degree inC ivil Engineering Major professor Dme 12/16/99 MS U is an Affirmative Action/Equal Opportunity Institution 0-12771 PLACE IN RETURN BOX to remove this checkout from your record. TO AVOID FINE return on or before date due. MAY BE RECALLED with earlier due date if requested. DATE DUE DATE DUE DATE DUE AN EVALUATION OF THE MPACTS OF CHANGEABLE MESSAGE SIGNS ON FREEWAY DIVERSION By Bellandra Benefield Foster A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Civil and Environmental Engineering 1999 ABSTRACT AN EVALUATION OF THE IMPACTS OF CHANGEABLE MESSAGE SIGNS ON FREEWAY DIVERSION By Bellandra Benefield Foster The focus of this research is to evaluate the Changeable Message Sign (CMS) component of the Intelligent Transportation Systems (ITS) construction project completed within southeastern Michigan. The changeable message sign and detector loop infrastructure construction began in 1997. The construction and field testing phases are scheduled for completion in 1999 by the Michigan Department of Transportation contractor. This research will explore three field sites within the ITS expansion area. The three sites were selected due to their configuration which allows a driver to make a choice to divert to a route other than their present route of travel. This diversion decision may be impacted by the changeable message sign display that exists along their travel path upstream from the decision point. Volume data for each site was obtained by analyzing the available loop detector measures of volume, speed and occupancy. Each site was analyzed on the basis of ‘with’ and ‘without’ CMS message activation. The ‘without’ condition includes site analyses during periods when either a blank or default message is displayed. The ‘with’ condition consists of periods when a specific informational type of driver information is displayed. Statistical significance of driver propensity to divert was analyzed based upon a comparison of traffic volume on the alternate routes. A simulation analysis of each site was completed using the FRESIM component of the CORSIM simulation software to determine simulated driver delay, and compare actual and simulated traffic speeds. Copyright by BELLANDRA BENEFIELD FOSTER 1999 ACKNOWLEDGMENTS First of all, to My Lord and Savior Jesus Christ, I LOVE YOU. You placed me on this earth with a specific purpose in mind. You blessed me with a committee of gentlemen who graciously agreed to serve on my Ph.D. committee. Dr. William Taylor, who served as my major advisor to this dissertation, was a tremendous source of guidance, inspiration and encouragement throughout the research period. I am also thankful for the remaining members of my dissertation committee, Drs. Thomas Maleck, Frank McKelvey, Joseph Gardiner, and Mumtaz Usmen for their beneficial suggestions throughout my study period. I appreciate the opportunity presented by the Michigan Department of Transportation to undertake this research project. I am thankfiil for a loving family and for my parents, George and Ella Benefield. They raised me with continuous love, discipline, and reverence of you, Lord. Throughout my life you have always shown yourself to be faithfiil as I walked within your comfort and love. You continued to guide me throughout my life by blessing me with my husband, Michael. When I prayed for a husband who would love me for a lifetime, you answered my prayer. Michael, I thank you for taking on this role in my life and I truly love you. 1 have never doubted that you have always wanted only what was best for me. I thank you for my sons, Lance Michael and William Aaron. I love them more than words can express and I am truly blessed by them. Thank you Lord for your guidance and comfort in fulfilling my ultimate and highest calling of being a wife and mother. I am thankful for the staff of B.B.F. Engineering Services, PC. I truly appreciate your effort, dedication and loyalty. I special thank you to Ahmed Abdel-Raheem for his assistance during my data retrieval process. I thank you for my fiiends Younger and Cynthia Taueg, Lila Petett, Brenda Peek, Cedric Dargin and Pastors Larry and Sylvia Jordan who continually display their kindness and encouragement to me and my family. Thank you Lord for your blessings, love, and for saving my life ----- AMEN. vi TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES INTRODUCTION CHAPTER 1 — RESEARCH PROJECT DESCRIPTION Project Perspective Purpose of the Evaluation Problem Statement Methodology Research Objectives CHAPTER 2 — LITERATURE REVIEW Factors Influencing Driver Behavior in Making Route Choices Driver Changeable Message Sign Design Characteristics Driver Changeable Message Sign Display Information Changeable Message Sign Location Planning CHAPTER 3 — SITE REVIEW AND DATA COLLECTION Site Descriptions: Eastbound I-96, East of Beck Road — Novi, Michigan Eastbound I-696 at Manistee — Oak Park, Michigan Westbound I-96 at Buchanan — Detroit, Michigan CHAPTER 4 — DATA DESCRIPTION AND RESULTS Real Time Data Collection Diversion Ratio Confidence Limits Simulation Analysis of Travel Time and Delay Sensitivity of Delay to Diversion Model Validation Analysis of Lane Closure Impact Due to Recurring or Non-Recurring Congestion Impact of Changeable Message Sign Display Messages on Traffic CHAPTER 5 — RESEARCH SUMNIARY AND CONCLUSIONS BIBLIOGRAPHY END NOTES vii APPENDIX A FRESIM Data Coding for Eastbound [-96, East of Beck Road — Novi, Michigan FRESIM Link-Node Diagram MDOT Loop Detector and Changeable Message Sign Hardware Addresses Michigan Department of Transportation Message Log APPENDIX B FRESIM Data Coding for Eastbound I-696 at Manistee — Oak Park, Michigan FRESIM Link-Node Diagram MDOT Loop Detector and Changeable Message Sign Hardware Addresses APPENDIX C FRESIM Data Coding for Westbound 1-96 at Buchanan — Detroit, Michigan FRESIM Link-Node Diagram MDOT Loop Detector and Changeable Message Sign Hardware Addresses Michigan Department of Transportation Message Log viii 1.01 4.01 4.02 . . 4.03 4.04 4.05 4.06 . 4.07 4.08 4.09 . . 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 4.18 LIST OF TABLES . MDOT Changeable Message Sign Display By Priority . EB I96 East of Beck AM. Peak Period Diversion Ratios . EB 196 East of Beck 6 am. to 7 am. Diversion Confidence Intervals . EB 196 East of Beck 7 am. to 9 am. Diversion Confidence Intervals . EB 196 East of Beck Road PM. Peak Period Diversion Ratios . EB 196 East of Beck 5 pm. to 6 pm. Diversion Confidence Intervals . EB 196 East of Beck 6 pm. to 7 pm. Diversion Confidence Intervals . Accident Occurrence With No CMS Message — EB 196 East of Beck Road . Accident Data With No CMS Message — EB 196 East of Beck Road . . EB 1696 at Manistee AM. Peak Period Diversion Ratios . EB 1696 at Manistee 6 am. to 7 am. Diversion Confidence Intervals . EB 1696 at Manistee 7 am. to 8 am. Diversion Confidence Intervals . EB 1696 at Manistee 8 am. to 9 am. Diversion Confidence Intervals . WB 196 at Buchanan PM. Peak Period Diversion Ratios . WB 196 at Buchanan 4 pm. to 6 pm. Diversion Confidence Intervals . WB 196 at Buchanan 6 pm. to 7 pm. Diversion Confidence Intervals . Simulation Volumes — EB 1696 at Manistee Street Simulation Measures of Effectiveness - Existing Volumes AM. Peak (6:45 am. — 7:45 am.) — EB 1696 at Manistee Street . Simulation Measures of Effectiveness — 10% Diversion to Ramp AM. Peak (6:45 am. — 7:45 am.) — EB 1696 at Manistee Street ix 4.19 4.20 4.21 4.22 4.23 4.24 4.25 4.26 4.27 4.28 4.29 4.30 4.31 LIST OF TABLES . Simulation Measures of Effectiveness — 10% Diversion to Mainline Freeway AM. Peak (6:45 am. — 7:45 am.) — EB 1696 at Manistee Street Simulation Volumes — WB 196 at Buchanan Street . Simulation Measures of Effectiveness — Existing Volumes PM. Peak (4:35 pm. — 5:35 pm.) — WB 196 at Buchanan Street . Simulation Measures of Effectiveness — 10% Diversion to Ramp PM. Peak (4:35 pm. - 5:35 pm.) ——WB 196 at Buchanan Street . Simulation Measures of Effectiveness — 10% Diversion to Mainline Freeway PM. Peak (4:35 pm. — 5:35 pm.) - WB 196 at Buchanan Street . Simulation Volumes — EB I96 East of Beck Road . Simulation Measures of Effectiveness — Existing Volumes AM. Peak (6:25 am. — 7:25 am.) — BB 196 East ofBeck Road Simulation Measures of Effectiveness -— 10% Diversion to Ramp AM. Peak (6:25 am. — 7:25 am.) — EB 196 East ofBeck Road Simulation Measures of Effectiveness — 10% Diversion to Mainline Freeway AM. Peak (6:25 am. — 7:25 am.) — EB 196 East ofBeck Road . Actual Speed Data 6:25 am. to 7:25 am. - BB 196 East of Beck Road . Eastbound 196 East of Beck Road Recurring/Non-Recurring Congestion Analysis . WB 196 at Buchanan Accident Message Display Analysis . WB 196 at Buchanan Accident Message Analysis — 12:55 pm. to 2:55 pm. 4.32 . 4.33 4.34 4.35 LIST OF TABLES . WB I96 at Buchanan Ratio Confidence Intervals . BB 196 East of Beck Accident Message Display Analysis BB 196 East of Beck Accident Message Analysis -— 3:40 pm. to 5:40 pm. . EB 196 East of Beck Ratio Confidence Intervals 3.01 3.02 .. 3.03 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 . . LIST OF FIGURES . Site Map for Eastbound 196, East of Beck Road - Novi, Michigan . . Site Map for Eastbound 1696 at Manistee — Oak Park, Michigan . Site Map for Westbound 196 at Buchanan — Detroit, Michigan . Eastbound 196 East of Beck Road — Ratio of 196 to 1275 Traffic Volumes . Eastbound 1696 at Manistee — Ratio of 1696 to I75 Traffic Volumes . Westbound 196 at Buchanan — Ratio of 196 to 194 Traffic Volumes . Eastbound 196 East of Beck Link-Node Diagram . Eastbound 196 East of Beck — Speed and Delay on Weaving Link (104-106) Ramp . Eastbound 196 East of Beck -— Speed and Delay on Weaving Link (104-106) Mainline . Eastbound 196 East of Beck — Speed and Delay at Exit Link Speeds When One Lane of 196 is Closed / Ramp Diversion Increases . Link Speeds When One Ramp Lane is Closed / Mainline Diversion Increases xii INTRODUCTION This research project included the field site review, data collection, computer simulation and data analysis of the impact of the Michigan Department of Transportation (MDOT) Changeable Message Signs (CMS) on traffic flow at specific locations. Variable message signs comprise a portion of MDOT’s 1996-1999 expansion of the Intelligent Transportation Systems (ITS) deployment in the southeastern Michigan area. The purpose of the ITS expansion is to assist the MDOT in managing freeway incidents, reducing congestion, and distributing traffic in response to planned and unplanned incidents. This evaluation report describes the impact of CMS on delay, and the percentage of freeway traffic diverted as a result of the CMS displays. Driver diversion was analyzed at three freeway locations where CMS are present. CHAPTER 1: RESEARCH PROJECT DESCRIPTION Project Perspective The investment of public funds can be justified on the basis of benefits and costs, and investment in freeway traffic management is no exception. The Michigan Department of Transportation (MDOT) has initiated the expansion of Intelligent Transportation System (ITS) deployment in Southeastern Michigan providing a unique opportunity to evaluate the net benefits of ITS deployment on a region wide basis. This public ITS implementation project promises to improve the flow of traffic on most area freeways. The new system should increase MDOT’s ability to respond to recurring and non-recurring congestion in the deployment area. However, the benefits and costs of the planned deployment are not known with certainty. While experience shows significant value in intelligent transportation systems technology, there is a need to quantify costs and benefits for public investment purposes. The MDOT Intelligent Transportation Systems deployment project provides a singular opportunity to evaluate the impact of a multifaceted region wide ITS deployment. The MDOT deployment plan was one of the first ITS plans of its kind, and the deployment will result in one of the most comprehensive Intelligent Transportation Systems in the nation. This deployment offered a unique opportunity to collect before- and-afier data to evaluate the effectiveness of ITS. It is unique in the sense that the plan is relatively comprehensive, it covers over 150 miles of urban freeway, and there was very little detection and traffic control technology deployed on the freeway system prior to this system expansion program. The conditions are ideal for a ‘before’ (generic or blank display) and ‘afier’ (priority message display) evaluation of the CMS -- something that has not been accomplished for any other major metropolitan area in the nation. The Advanced Traffic Management System (ATMS) and Advanced Traveler Information System (ATIS) expansion should assist MDOT in managing freeway incidents, reducing congestion, and distributing traffic in response to events and incidents. By quickly identifying, verifying, and responding to incidents, MDOT should see substantial reductions in system delay. Ideally, MDOT’s efforts will be coordinated with other agencies in the region for a more fully integrated management approach. The intent is to achieve greater throughput while also reducing the variability in flow and trip times. The results of this project will enhance the ability of MDOT to assess the impacts resulting from deploying ITS Advanced Traveler Information technologies. In addition this study can make a significant contribution to our understanding of ITS deployment, locally and nationally. Phase one of the ITS evaluation included a Congestion Assessment Study. A measure of corridor and system congestion was developed and approved by MDOT. The second phase of the ITS evaluation is designed to determine whether these measures are increased or decreased by the implementation. To establish the baseline conditions, volume data were collected from selected instrumented corridors during periods when message displays either contained a default message, or were blank. Nine months of historical data were obtained from the current MDOT loop detectors in the Detroit area. Changeable message signs were deployed to communicate site-specific information to the motoring public. The evaluation was based on a comparison of data when priority, default, or blank CMS’s were displayed, including driver diversion under each of these conditions. The purpose of this study was to evaluate the impact of providing information to the driver in terms of measures of effectiveness, which will assess freeway operations. At the study locations used in this research, changeable message signs are used to provide traffic information, traffic warnings, regulations, routing, and traffic management information to highway users. They are designed to affect the behavior of motorists by providing real-time highway related information. As of July 1999, a total of 15,680 messages were available to the operator of the CMS located in the Michigan Department of Transportation traffic management center. These messages are listed by MDOT priority category as shown in Table 1.01. In addition to the five categories listed, a blank message board is also a display alternative. Table 1.01 - MDOT Changeable Message Sign Display By Priority l. Incident Management (accidents, freeway closures, etc.) 2. Traffic Management (incident and/or special event detours or road work) 3. Construction (e. g., Fines Doubled in Construction Zones) 4. Safety (e. g., State Troopers Wear Their Seat Belts, Do You?) 5. Non-MDOT, transportation related messages (e. g., Detroit Metro Airport Closed Due To Fog) Messages within categories 3 through 5 scroll every 8 seconds. Message types 1 and 2 do not scroll. The Michigan Intelligent Transportation Systems Center (MITSC), which will control the CMS sites, refuses to post the following types of messages: advertising, promotions, telephone numbers, directing motorists to certain locations while diverting them from others to the detriment of commercial interests, non-traffic related messages, and others at the discretion of the MITSC directors. Messages containing the word ‘congestion’ will not be displayed due to motorist survey results, which revealed variations in driver perception of the meaning of this word. The measures of effectiveness used in this research include reductions in delay, and percentage of diversion based upon message type displayed. The computer simulations for each analysis site include data which measure the delay consequences of incident induced or recurring congestion as a result of a drivers’ decision to divert or not divert. Other measures of effectiveness which are available from the computer simulation include speed, fuel consumption, and air quality impacts. However, these measures were not used in this project. Purpose of the Evaluation This evaluation was designed to assess the benefits and costs of the CMS component of this ATMS/ATIS expansion program. The evaluation emphasized the benefits of incident management and traffic diversion, which are the most likely benefits from CMS. Some specific evaluation questions to be answered by the evaluation project include the following: What are the impacts of traffic diversion on delay? Specifically, what happens to delay and travel times when there is driver diversion under recurring and non-recurring congestion? How well is the CMS service operating? What are the impacts of a CMS message on driver route selection? Problem Statement The objective of this research project is to evaluate the impacts of a CMS providing motorist information during peak and non-peak hours on the freeway. The FRESIM traffic simulation program will be used to evaluate traffic conditions at each diversion site selected for evaluation. The study locations include three new CMS sites. The FRESIM simulation program assists the user in determining the value of various measures of effectiveness. The following measures will be utilized to evaluate the MOE’s for each CMS analysis location. Vehicles In - Total number of vehicles which entered the upstream link and each of the downstream links since the beginning of the simulation. Vehicles Out - Total number of vehicles discharged from these links since the beginning of the simulation. Average Total Travel Time —— Average vehicle minutes of travel time incurred by all vehicles that traversed the upstream link and one of the downstream links since the beginning of the simulation. Moving Time - Average travel time of the vehicles on the network while moving at a speed greater than zero. 0 Delay Time in Units of Vehicle Seconds — Total time in which vehicles are slowed or stopped en-route through the network due to congestion delays. The difference between the Total Travel Time when allowed to travel at posted speed, and the Total Travel Time when congested traffic congestions result in delays. 0 Density in Units of Vehicles/Lane Mile - Ratio of the average number of vehicles to the total lane-miles on each link. 0 Speed in Units of Miles per Hour - Ratio of the Vehicle-Miles to Vehicle- Hours. Methodology The evaluation included monitoring detectors both upstream and downstream at three locations where CMS’s are installed (diversion points). Analysis of speed and volume measures were performed under the following conditions: a. The system displays a message within priority category 4 or 5 as stated in Table 1.01. b. The system displays a message within priority categories 1, 2, or 3 as stated in Table 1.01. Total freeway volume upstream from the nearest freeway diversion point downstream from the CMS, and the fi'eeway volume on each of the alternative paths at the diversion point were compared. A simulation analysis of the freeway segment studied was conducted to conduct the incident impact analyses. The following CMS locations were selected: 1. Eastbound I-96 east of Beck Road — City of Novi, Michigan 2. Eastbound I-696 at Manistee — City of Oak Park, Michigan 3. Westbound 1-96 at Buchanan — City of Detroit, Michigan Research Objectives The objectives of this research were to: 1. Determine the impacts on driver diversion and speed due to the display of priority messages, versus generic message or blank display periods. 2. Based upon the computer simulation models developed for the selected sites, evaluate freeway incident impacts by varying the capacity of the freeway segments to simulate varying degrees of incident severity. CHAPTER 2: LITERATURE REVIEW Factors Influencing Driver Behavior in Mm Route Choices Driver travel behavior can be effected by two primary situations: 1) the traveler makes a one-time decision to change the planned travel route or travel time based upon the influence of an external event, such as traffic information and 2) a drivers’ typical travel habits are modified over some time period due to changing circumstances in their environment. In the first situation, a message displayed on a changeable message sign could be used by the driver in selecting a route. The possible driver responses to the information displayed on a CMS would be to do nothing or to take an alternate route, depending on; the degree of congestion, the clarity, usefulness and reliability of the displayed information, and the individual driver tolerance to the prevailing traffic conditions: 1 The reaction of a driver is also determined by the individual’s past experience in obtaining and utilizing traffic information. Many drivers may not use traffic recommendations due to one or more of the following reasons:2 0 An acceptable alternative route is unavailable during the drivers’ time of travel. 0 The variable message sign information displayed is not relevant or reliable. o The traffic usually clears within an acceptable length of time for the driver. 0 Driver fear of getting lost if an alternative route is used. Driver diversion behavior has been researched using the stated preference approach, the revealed/reported preference approach, or the field study approach.3 The primary goal of the stated preference approach is to analyze what drivers say they would do in response to hypothetical traveling situations. The revealed preference approach analyzes driver behavior in real-life situations on the basis of reports from the respondents about previous actions or responses to typical driving situations. This research study is based upon the field study approach, which consists of the analysis of driver behavior through field observation of traffic, including observation of actual diversion behavior in response to specific messages. Based upon a survey completed by Wohlschlaeger“, in order of importance, the survey results revealed that motorists prefer to travel a route which is more direct, faster and less congested than the alternate routes. Based upon studies completed by Huchingson and Dudek,5 using the stated preference approach, the median value of delay for drivers to make the decision to divert was 15-20 minutes for different locations within the United States. A study in Houston, Texas found the median value of delay for diversion to be only 5-6 minutes in the case where a service road is available as a convenient alternative route.6 The research completed by Khattak, Schofer, and Kopplemen provided a summary of factors that were found to influence driver diversion behavior. These factors included the following:7 0 Level of Traffic Information 0 Travel Time on the Preferred Route 0 Travel Time on an Alternative Route 0 Delay on the Preferred Route 0 Congestion on the Preferred Route 0 Congestion on the Alternative Route 10 o Familiarity with the Alternative Route 0 Number of Traffic Stops on the Preferred and Alternative Routes8 Diversion behavior relative to an immediate warning message was studied by Firmin, Bonsall and Beaumont9 with the following results: Driver Stated Reaction to Immediate Warning Message Divert at Next Opportunity 54% Delay Diversion Until Problems Occur 14% Would Not Divert — Continue to Proceed Ahead 32% A 1997 survey completed by the Hanshin Japan Expressway Public Corporationlo included questions pertaining to drivers’ desire for traffic information. One of the primary goals of the survey was to understand drivers’ needs for traffic information. The survey included a section for driver response to informational devices or media. In response to a listing of various methods of information transmittal, 50% of drivers considered AM/FM radio as the most desirable method. It is believed that this response is due to the simplicity and familiarity of AM/FM to drivers in receiving traffic information. Research completed by Khattak, Schofer, and Koppleman,11 indicated that drivers can successfully be diverted to alternate routes during special events through display of diversion messages. There was not enough evidence to indicate that drivers can be diverted during incidents. Field study results based upon research completed by Dudek ll in San Antonio, Texas, revealed no statistical evidence that diversion increased due to the messages displayed under incident conditions. 12 A model of driver response to delay was developed by Khattak, Schofer and Koppleman. The model predicts the increased propensity to divert based upon the following; number of alternative routes which the driver has formerly used, length of delay on preferred route, driver travel time, the drivers’ risk taking behavior, and the driver’s preferences about diverting. Other influential factors included driver gender and residential location.13 The model also indicated an increased likelihood of a driver to take an alternate route if they received delay information through traffic reports as opposed to visual observation of traffic delays. Evidenced from prior research in various aspects of traffic information, there is a close relationship between the acquisition of traveler information and the quality of information. Based upon research completed in 1994 by the Peter Harris Research Group,14 a widely accepted hypothesis states that as the information quality improves, the more people are likely to use the information. A driver perceives quality of information in terms of clarity, usefirlness and reliability of the displayed information. Although the literature review revealed that one study found no statistical evidence to support the hypothesis that CMS message displays increase a driver’s diversion probability, most studies resulted in the conclusion that driver’s show an increased potential to divert based upon CMS message information. 12 Driver Changeable Message Sign Des_ign Characteristics Variable message signs have been used in highway applications in the United States for over 30 years. In the early 1970’s, computer equipment to control the devices became relatively inexpensive, and many manufacturers began incorporating computer technology into their designs. This development was significant in providing unlimited message capability.15 In terms of the technology used, variable message signs can be classified into three categories: 1. Light reflecting 2. Light emitting 3. Hybrid Light reflecting signs reflect light from an external light source such as the sun or automobile headlights. Light emitting signs generate their own light on or behind the viewing surface. Some manufacturers have combined the two technologies to produce hybrid displays which exhibit the qualities of both light reflecting and light emitting devices. In the case studies that are the focus of this research, the cms manufacturer is Voltron, Incorporated. The locations are equipped with hybrid type signs that combine light emitting and light reflecting technologies. When a driver uses the information available on traffic reporting devices, such as a cms, benefits can occur in many ways. In addition to travel time savings, the intangible benefits include reduced anxiety, increased knowledge of travel options, increased reliability, and enhanced ability to avoid congestion and a reduction in the possibility of 13 getting lost.16 Based upon a research survey completed by Yim, Hall and Weissenberger, driver survey participants stated the most significant benefit received from traffic reports as the ability to make informed decisions. Other important benefits as reported by the driver included travel time savings, and a reduction in driver anxiety. Changeable Message Sign Display Informtion To be effective, a CMS must achieve the following:17 Attract the motorists’ attention Be legible and provide significant legibility distance. Cause minimal visual discomfort to the driver. Be effective under a variety of lighting conditions, including bright daylight, night, and low sun angles. Be effective under backlight and washout conditions — where backlight describes the condition where the sun is directly behind the sign and washout occurs when the sun is directly behind the driver. When a driver simulation study was performed to evaluate different forms of variable route guidance messages at the TNO Institute for Perception in the Netherlands, the conclusions of the study included the following:18 1. The changeable message sign (CMS) format has a considerable influence on driver propensity to diverge from a ‘normal’ route. Of the CMS implementations reported, the combination of crossing out the critical destination of the main sign with an 14 indication of the reason that diverging is advised was the most effective message format. 2. More persuasive messages lead to less hesitation in driving behavior at the diversion point. A case study was completed using drivers in Seattle, Washington. The purpose of the study was to investigate commuter behavior and decision making to develop functional requirements for an advanced driver information system. Results from the initial survey indicated that motorists could be clustered into four commuter groups, based upon variables that indicated how they modified their willingness to change departure time, route, or mode. The study defined the following motorist groups:19 0 Route changers (20.6%) — motorists who were familiar with alternative routes and were willing to change routes before entering the major commuter freeway. o Non-changers (23.4%) — motorists who were unwilling to change time, route, and mode. 0 Route and time changers (40.1%) — motorists who were willing to change route and departure time. 0 Before or ‘pretrip’ changers (15.9%) — motorists who were willing to make time, mode, or route changes before leaving home for their morning commute. Approximately 1% of the route changers and non changer groups (11 of 1,588) indicated a willingness to adjust the time they left for work based on traffic information, as opposed to over 99% of the route and time changers and pretrip changer groups (2,010 of 2,018). 15 The survey subjects were asked to rank the various forms of information contained within the message display screen according to how helpful they felt the information would be in selecting a driving option. Ranking values were from one to five, with one being the most helpfirl. Time of delay estimates were clearly preferred across all commuter groups with a mean rank value of 1.97. Text messages ranked second with a mean value of 2.32 across all commuter groups except the non-changers. Pictures of actual traffic were ranked third with a mean of 2.86, and maps fourth with a mean of 3.17. Bar graphs shown on CMS’s as a method of representing traffic conditions ranked a distant fifth with a mean of 4.5 1 .20 In a study completed by M. Brocken and M. Van der Vlist,” the analysis of driving behavior at the diversion point in relationship with the inclination to diverge reveals that both are inter-related. The results of the study revealed that CMS configurations which contained all of the information drivers desired resulted in less hesitant behavior than in conditions when CMS’s lacked the desired information. A high inclination to diverge appeared to be accompanied by early exiting and by maintaining a relatively high speed. According to the simulator results of this research, driver compliance rate to CMS display information is highest when the divergence is recommended based upon the message displayed. A route information system would provide CMS system evaluators with a better explanation of the variability in route choice behavior than would a route recommendation system. A route information system would include congestion and travel time information and route recommendations indicate specific alternate route(s). In a study completed by Firmin, Bonsall and Beaumont,22 driver attitudes toward information from CMS’s implemented in London were investigated through the 16 CLEOPATRA Project. The sign message texts for 22 signs within the study area were set by the Metropolitan Police Department. Two basic message types are used, immediate warning messages and advance warning messages. Common legends in the advance warning messages for the London CMS system include; the date and time of a roadway incident, incident location, cause for the incident and recommendation(s) for driver alternative action. Common legends for causes of the roadway incidents include the following wording: o ACCIDENT o CONGESTION o ROADWORK Commonly recommended legends for driver action or driver expectations include: o DELAYS 0 LONG DELAYS o AVOID AREA 0 CLOSED o DIVERSION o SLOW DOWN Another facet of this study was a survey to determine driver interpretation and preference for the message board when there are no relevant messages. The survey results of this study of reactions to a blank CMS were:23 17 Driver Interpretation of Blank Variable Message Signs No Problems Ahead 57% No Information Available 35% Other 8% Information Preference When No Information Is Indicated Blank VMS Sign 27% A Message Stating ‘No Information’ 17% A Message Displaying the Speed Limit 13% A Message Displaying the Time of Day 12% A Message Stating ‘Light Traffic’ 9% Other 22% The study concluded that drivers’ preferences tend to be for up-to-date information and notification of alternative routes. Drivers would prefer to receive information specific to the route they are travelling and have signs used when no warning messages are available, rather than being left blank. The results of a research study completed by the Ministry of Transportation in Ontario concluded the following as a result of a survey of 539 drivers on message display preferences.24 0 The most preferred term for stop-and-go traffic overall was ‘Heavy Congestion’. I8 Equal numbers of drivers preferred to be warned 2 to 3 kilometers or 4 to 5 kilometers in advance of traffic problems. To describe rush hour congestion, respondents preferred the terminology ‘Rush Hour Conditions Next 5 Kilometers’. To describe normal free flowing traffic conditions, respondents preferred the terminology ‘Normal Traffic Next 5 Kilometers’. Messages n_ot_ relating to traffic conditions were clearly opposed by the majority of respondents. The greatest diversions were indicated when a message about lane closure, congestion or reduced speed was combined with an action directive such as ‘Heavy Congestion Ahead. . . .Use Collector Lanes’. A 1997 survey completed by the Hanshin Japan Expressway Public Corporation25 included questions pertaining to drivers’ needs for traffic information. The questionnaire consisted of the following four parts: 1. 2. Individual respondent attributes Evaluation of the present information provided by the existing expressway information system Travel behavior at the time of receipt of the questionnaire Driver assessment of type(s) of information and device needs The survey results revealed that 50% of drivers always or frequently pay attention to information pertaining to congestion. The results also revealed that more than 60% of drivers make use of the travel time information for their route choice, and about 40% of 19 drivers consider the information useful for reducing their irritation in congested traffic conditions. Of the 45% of survey respondents that stated congestion information is most desirable, the percentage of those who chose congestion and estimated travel time as most desirable information is over 85%. Driver preferences for future investments pertaining to the vms signing were surveyed in the study completed by Firmin, Bonsall and Beaumont.26 The driver responses resulted in the following: Driver Preference for Future Sign Investment Funds Provide More Signs 37% Update Information More Frequently 36% Maintain and Improve Ordinary Signs 15% Provide More Information on Signs 11% Do Not Invest in Variable Message Signs 1% Research completed by Khattak, Schofer and Koppleman27 included driver expected length of delay, regular travel time on the usual route, and anticipated congestion level on the alternate route as three of the factors which influence en route diversion behavior. Changeable Message Sign Location Plflnirgg Based upon the review of a research document completed by Leo D. Klein of the I-INTB Corporation,28 the most desirable location for a CMS is overhead, so the sign is in 20 the motorists’ direct line of sight. For interstate roadway systems, the signs should be placed about % mile before the alternative route decision point. A study completed by the Ministry of Transportation of Ontario defines the appropriate distance of a CMS from the gore of the downstream diversion point as follows:29 (Safe Weaving Distance + Reaction Distance — Sight Distance) Where: Safe Weaving Distance = 1,000 meters (at Level of Service D) Reaction Distance = 60 meters (2 seconds at 100 kilometers or 197 linear feet) Sight Distance = 270 meters (886 linear feet) Therefore: Minimum Distance (CMS to Diversion Point) = 1000 + 60 - 270 = 790 Meters (2,592 linear feet) In order to provide a factor of safety to this calculation, the changeable message signs are preferably located more than 900 meters before the diversion point. The Ministry of Ontario study provided a summary of placement guidelines for CMS sign locations on Highway 401. These guidelines are summarized as follows:30 0 Locate CMS 900 meters to 1,200 meters upstream of a diversion point. 0 Locate CMS 300 meters upstream of any existing sign. 0 Locate CMS such that all drivers entering the freeway have an opportunity to view a CMS before their first opportunity to utilize collector or expressway transfer roadways or other major diversion points. 21 o Desirable minimum spacing between CMS’s is 3,000 meters and desirable maximum spacing is 5,000 meters. 0 Locate CMS’s over the collector lanes and adjacent to express lanes (if applicable) more than 150 meters apart along the freeway. Based upon research completed by Upchurch, Thomas, Armstrong and Baaj, a CMS must be legible from a sufficient distance such that the driver, at a typical travel speed, has enough time to read the message. Based upon a review of previous research, a minimum exposure time of 6.0 seconds on a three line sign is recommended. As drivers approach an overhead sign, sign readability becomes restricted by the vertical cut-off angle of the windshield. The sign will become hidden from the motorist’s view at a distance of about 150 feet. Based upon a 60 mile per hour travel speed, to be acceptable, a CMS sign with a three-line message should be legible from a minimum distance of 678 feet.31 Each of the CMS sign locations analyzed in this research contains three-line message displays, and they all meet this criterion. 22 CHAPTER 3: SITE REVIEW LOCATIONS AND DATA COLLECTION firstbound I-96 Bag of Beck Road This analysis site is located along eastbound I-96 within the city of Novi, Michigan. ' The CMS at this site is the only one that is not positioned on an overhead structure. The CMS is located on a tower structure located on the south side of the freeway. Traveling eastbound, a driver would traverse the freeway detector loops and enter into the analysis site at 9,665 feet past the centerline of the Beck Road overpass. The changeable message sign tower is positioned on the right side of the freeway at the same milepoint as the detector loops. Based upon the message displayed on the CMS, the driver would make a decision to remain on [-96 which transitions to eastbound I-696, or divert to southbound [-275 This analysis site presents the possibility for the driver to reach a destination in downtown Detroit by using either I-696 and M-lO or I-275 and I-96. The diversion analysis will be based upon the percentage of drivers who travel on I- 696 versus the drivers who divert to southbound I-275. After passing the CMS, the driver would continue to travel 15,520 feet within the analysis zone to reach the exit detection loops on I-696. If the driver diverts to southbound I-275, the distance from the CMS to the diversion route exit loops is 9,500 feet. Based upon an analysis of volume data for five dates available in the months of November and December 1998, this site has a morning peak hour that occurs between 6:25 am. and 7:25 am. Figure 3.01 shows the site area with approximate locations of the detector loops and CMS labeled. 23 o «9‘ R ’5 LE 13 MILE now E > 3 fa r: V: w a z 3) o E / § w L OAD 12MlLE ROAD 1 12 MLEROAD fl 3, a, 2 2 E U 3 ..~- . 31 3 3%? CMS TOWER -. , %: HILL TECH EB [96 .3? "33$ RA/E AVE E8 196 ENTRY DETECTORS EB I696 RANIP ’ DETECTORS 1 MILE ROME Novl 1 MILE 11 MILE no : 73.1 g i .11 IINQENTI " E _‘ SB [275 r RAW J1 . 5 a DETEC roas ’4 w - o 5 a — “We 11 ER 2 2 2 m 10 E R D 10 MLE ROAD LE § a i 0 r 5 ‘1 < \ r. n a it‘s” 5 '3 J m C MEMO 53‘ ur c1 GeoSystems Global Corp C Figure 3.01 - Site Map for Eastbound 196, East of Beck Road — Novi, Michigan USA98 Streets and Destinations is a Trademark of Sierra Online, Incorporated. Copyright 1991-1998 GeoSystems Global Corporation. Used With Permission. 24 All Rights Reserved. Maps Eastbound [-696 at Mzflstee This analysis site is located along eastbound 1-696 within the city of Oak Park, Michigan. Traveling eastbound, a driver would traverse the freeway detector loops into the analysis zone at a point 5,540 feet east of the changeable message sign which is located on the Manistee Street bridge overpass. Based upon the message displayed on the CMS, the driver would make a decision to remain on I-696 or divert to northbound (or southbound) I-75. Based upon a combination of freeway and arterial route choices, a driver could reach a destination in the northeast section of the Detroit Metropolitan area by using either eastbound 1-696 or northbound 1-75. The diversion analysis will be based upon the percentage of drivers who continue using [-696 compared with those who choose to divert to northbound 1-75. Afier passing the CMS, the driver would continue to travel 14,370 feet within the analysis zone to reach the exit detection loops on eastbound 1-696. If the driver chooses to divert to I-75, the distance from the CMS to the diversion route exit loops is 14,400 feet. Figure 3.02 shows the site area with approximate locations of the detector loops and CMS labeled. 25 EB I696 DETECTORS EB 1696 NB r75 EXIT RAMP EB 1696 ENTRY DETECTORS DETECTORS SB 175 EXIT RAMP DETECTORS 01991-1997 Figare 3.02 - Site Map for Eastbound 1696 at Manistee — Oak Park Michigan USA98 Streets and Destinations is a Trademark of Sierra Online, Incorporated. Copyright 1991-1998 GeoSystems Global Corporation. All Rights Reserved. Maps Used With Permission. 26 Westbound I-96 fiuchanan This analysis site is located along westbound 1-96 within the city of Detroit, Michigan. Traveling westbound, a driver would travel 2,890 feet west of the site entrance loops to the CMS that is located on the Buchanan Street bridge overpass. Based upon the message displayed on the CMS, the driver would make a decision to remain on I-96 or divert to eastbound 1-94. Based upon a combination of freeway and arterial route choices, a driver could reach a destination in the western suburbs of the Detroit Metropolitan area by using either westbound 1-96 or a combination of I-94 and M-IO. The diversion analysis will be based upon the percentage of drivers who continue to use I-96, compared with those who choose to divert to eastbound I-94. After passing the CMS, the driver would continue to travel 4,300 feet within the analysis zone to reach the exit detection loops on westbound 1-96. If the driver chooses to divert to eastbound I-94, the distance from the CMS to the diversion route exit loops is 2,070 feet. Figure 3.03 shows the site area with approximate locations of the detector loops and CMS labeled. 27 '. .0 ‘ " ’\%‘\\\ \ ‘ “ ’ i O \‘a \wggggrgaa a \- \ \\%\\$ 3‘39“? “V a.- “an" , «3 ‘MMR‘EQQQ 733:... ‘ VV‘ 3"" ’ . 91‘. , ‘ 01991-1997 ‘21 GeoSystems Global Corp re 3.03 - Site Ma for Westbound 196 at Buchanan — Detroit MI USA98 Streets and Destinations is a Trademark of Sierra Online, Incorporated. Copyright 1991-1998 GeoSystems Global Corporation. All Rights Reserved. Maps Used With Permission. 28 CHAPTER 4: DATA DESCRIPTION AND RESULTS R311 Time Data Collection As built plans for each analysis site were reviewed to obtain the specific loop and CMS hardware addresses. Each ‘address’ consisted of a number assigned to each loop segment. As part of the construction of the ITS project in southeastern Michigan, the design included assigning hardware addresses for CMS and loop locations. Site entrance, exit and ramp loops were used to obtain the required real-time data for each analysis site. Data were available beginning in November 1998. Data tapes containing the loop data were formatted for use within the statistical analysis program SPSS (version 9.0). Two data directories were established for each analysis site. One directory was used to establish data files for the time period of November and December 1998. This time period was early in the CMS message development phase; therefore most display text consisted of default messages that were unrelated to specific incident occurrences. The second directory contained 1999 data for January through May 1999. Real time data were available for various dates in 1999. Data for Friday through Monday was avoided due to a higher potential for increased variances in traffic volumes. Diversion Ratio Confidence Limits The ratio of drivers who exited the analysis site via the mainline exit compared to the ramp exit were compared for the peak morning or afiemoon volume period at each analysis site. The dates used for this analysis were: 29 0 Wednesday, November 17, 1998 0 Thursday, November 18, 1998 0 Tuesday, December 8, 1998 0 Wednesday, December 9, 1998 0 Thursday, December 10, 1998 Each site was analyzed to determine the volume ratio between the mainline freeway and the exit ramp for the condition when there were no messages on the CMS. The analysis was completed for the higher of the peak morning or aftemoon traffic volume period of6 am. to 9 am. or 4 pm. to 7 pm. Eastbound I-96 East of Beck Road The diversion ratios for the eastbound I-96 at Beck site for the peak three-hour moming travel period are recorded in Table 4.01, and shown graphically in Figure 4.01: 30 Table 4.01 —- EB 196 East of Beck AM. Peak Period Diversion Ratios Date Time (a.m.) Ratio Mean Mean Ramp Mean Mainline Exit Volume Mainline Exit Volume Exit Speed onph) 11/17/98 6:00-7:00 1.18 3354 2837 64.00 11/18/98 600-7200 1.16 3378 2902 67.00 12/08/98 6 :00-7200 1.20 3514 2923 67 .00 12/09/98 6:00-7z00 1.20 3417 2852 68.00 12/10/98 6:00-7100 1.16 3361 2898 68.00 11/17/98 7:00-8:00 1.30 3947 3031 54.00 11/18/98 7:00-8:00 1.36 4203 3101 64.00 12/08/98 7:00-8:00 1.27 3871 3028 48.00 12/09/98 7:00-8:00 1.28 4021 3136 51.00 12/10/98 7:00-8:00 1.31 4136 3162 58.00 11/17/98 8:00-9:00 1.35 3506 2606 59.00 11/18/98 8:00-9:00 1.36 3438 2520 67.00 12/08/98 8 :00-9:00 1.28 3582 2777 61.00 12/09/98 8 200-9200 *1.08 2857 2653 *28.00 12/10/98 8 :00-9:00 1.27 3502 2764 62.00 1 . 4k f rfigfl I! 1“ IX \‘g MEAN RATI 0 I... 1.21 (man, I J / XX. 1 ETD-Cf 1’ ‘1“; 1.1L 6-7 6-7 6-7 7-8 7-8 8-9 8-9 8-9 PEAK PERIOD 6 a.m. T0 9 a.m. Figure 4.01 — EB 196 East of Beck Road - Ratio of 196 to 1275 Traffic Volumes 31 *Based upon a review of the consistency of the information shown in Table 4.01, the data shown for the date of 12/09/98 for the time period of 8:00 to 9:00 am. will be rejected. The presumption is that either an incident occurred at this time or the data for this date and time period were not accurate due to an equipment malfunction. The t statistic was used to determine confidence intervals since both volume populations are found to be normally distributed with equal population variances based on an analysis of a random sample of volumes over the two-month period. The t statistic was used to construct confidence intervals for the mean volume ratios for the peak traffic volume period of 6:00 am. to 7:00 am. and 7:00 am. to 9:00 am. Ratios found to be outside of the confidence limits for this time period will indicate that the ratio of the mainline volume to the ramp volume differs from the base conditions. The results for the 95%, 98% and 99% confidence levels are shown in Tables 4.02 and 4.03. Table 4.02 - EB 196 East of Beck 6 am. to 7 am. Diversion Confidence Intervals Significance Level Confidence Interval 99% 1.139, 1.221 98% 1.147, 1.217 95% 1.155, 1.205 Table 4.03 - EB 196 East of Beck 7 am. to 9 am. Diversion Confidence Intervals Significance Level Confidence Interval 99% 1.268, 1.352 98% 1.273, 1.346 95% 1.282, 1.338 32 Accident occurrence data were available for the months of November and December (1998). The data is sorted by MDOT control section, state trunkline, and milepoint. The accident data were reviewed for dates and times where an accident occurred during the peak travel periods for each site. This review revealed two accidents that occurred along the eastbound 196 at Beck Road site. The accidents occurred on November 17, 1998 at 5:00 pm. and December 7, 1998 at 6:00 pm. These dates were included in the data that was retrieved to construct the confidence limits. Since both incidents occurred in the afiemoon peak period rather than the morning peak period, diversion confidence limits were determined for the afternoon peak as well to determine whether the diversion ratio changed as a result of these accidents. The diversion ratio for the afiemoon peak period is shown in Table 4.04. Table 4.04 - EB 196 East of Beck PM. Peak Period Diversion Ratios Date Time (p.m.) Ratio Mean Mean Mean Mainline Ramp Exit Mainline Exit Volume Volume Exit Speed (mph) 1 1/17/98 4:00-5:00 0.83 2007 2424 68.00 11/18/98 4:00-5:00 0.86 2239 2590 68.00 12/08/98 4:00-5:00 0.86 2142 2495 68.00 12/09/98 4:00-5:00 0.84 2144 2567 67.00 12/10/98 4:00-5:00 0.94 2458 2624 67.00 4 : .11/17/98 ; 5300;15:001- * ~ - : 0.87 2121 fr .5 3:;.:;;.;2..»133;;g : ' -* . 1: 3559.00,?" 11/18/98 5:00-6:00 1.04 2162 2076 67.00 12/08/98 5:00-6:00 0.89 2144 2409 68.00 12/09/98 5 :00—6200 0.93 23 02 2474 68.00 12/10/98 5 :00-6:00 0.91 2262 2478 66.00 11/17/98 6:00-7:00 0.79 1693 2143 68.00 11/18/98 6:00-7:00 1.04 1781 1705 67.00 12/08/98 6:00-7:00 0.87 1678 1929 69.00 12/09/98 6:00-7:00 0.83 1649 1989 68.00 __12/10/98 6:00-7:00 0.95 1759 1852 67.00 33 The t statistic was used to calculate the 95%, 98% and 99% confidence levels for the volume ratios between 5:00 pm. and 6:00 pm. and 6:00 pm. and 7:00 pm, excluding the days when accidents occurred. These limits are shown in Tables 4.05 and 4.06: Table 4.05 — EB 196 East of Beck 5 pm. to 6 pm. Diversion Confidence Intervals Significance Level Diversion Confidence Interval 99% 0.74, 1.14 98% 0.79, 1.09 95% 0.84, 1.05 Table 4.06 — EB [96 East of Beck 6 pm. to 7 pm. Diversion Confidence Intervals Significance Level Diversion Confidence Interval 99% 0.69, 1.10 98% 0.72, 1.07 95% 0.77, 1.02 The analyses of the confidence limits for these dates were used to determine whether the accident occurrence had an impact on traflic conditions when no CMS message was available as a driver aide. Table 4.07 details the information pertaining to the accident occurrences on the dates in which the CMS did not display information to the motorist on the date and time of the accidents. 34 Table 4.07 Accident Occurrence With No CMS Message — EB 196 East of Beck Road Date Time Location Type Injuries # Vehicles Involved 11/17/98 5:00 p.m. West of Sideswipe 0 2 Haggerty 12/7/98 6:00 p.m. West of Fixed 0 1 Grand Object River The driver diversion ratio was computed using the traffic volume data for the date of November 17, 1998 and December 7, 1998. Table 4.08 Accident Data With No CMS Message - BB 196 East of Beck Road Date Accident Ratio Mean Mean Ramp Mean Occurrence Mainline Exit Volume Mainline Time (p.m.) Exit Volume Exit Speed (mph) 11/17/98 5:00 0.87 2121 2438 69 12/7/98 6:00 0.84 1484 1759 65 The diversion ratios of 0.84 and 0.87 are both within the confidence interval for their respective hour as shown in Tables 4.05 and 4.06. Therefore we cannot reject the hypothesis that the accident occurrence had no impact on the driver’s decision to stay on the mainline freeway or divert to the ramp to southbound I-275 in the absence of advanced information provided by a CMS. 35 Eastbound I-696 at Manistee The diversion ratios for the eastbound I-696 at Manistee Street site for the peak three hour morning travel period are recorded in Table 4.09, and shown graphically in Figure 4.02: Table 4.09 - EB 1696 at Manistee AM. Peak Period Diversion Ratios Date Time (a.m.) Ratio Mean Mean Ramp Mean Mainline Exit Volume Mainline Exit Volume Exit Speed (mph) 11/17/98 6:00-7:00 1.87 3696 1979 67 11/18/98 6:00-7:00 1.88 3701 1967 68 12/08/98 6:00-7:00 1.88 3848 2050 67 12/09/98 6:00-7 :00 1.89 3770 1992 68 12/10/98 6:00-7:00 1.88 3729 1982 69 11/17/98 7:00-8:00 2.26 5283 2336 64 1 1/18/98 7:00-8:00 2.42 5473 2266 64 12/08/98 7 :00-8:00 2.29 5442 2377 64 12/09/98 7 :00-8 :00 2.30 5468 2380 64 12/10/98 7:00-8:00 2.38 5473 2297 64 1 1/17/98 8:00-9:00 2.08 4716 2264 62 1 1/18/98 8:00-9:00 2.00 4738 2372 64 12/08/98 8:00-9:00 *2.73 4760 1741 58 12/09/98 8:00-9:00 1.94 4134 2132 66 12/10/98 8:00-9:00 2.07 4807 2321 63 36 MEAN RATIO *Based upon a review of the consistency of the information shown in Table 4.09, the data shown for the date of 12/08/98 for the time period of 8:00 to 9:00 am. will be rejected. The presumption is that either an incident occurred at this time or the data for this date 2.5 2.4 2.3 6—7 6-7 7—8 7—8 7-8 8-9 8-9 PEAK PERIOD 6 a.m. T0 9 a.m. Figure 4.02 — EB 1696 at Manistee — Ratio of 1696 to 175 Traffic Volumes and time period were not accurate due to an equipment malfunction. As with the first site, the t statistic was used to calculate the 95%, 98% and 99% confidence levels. Manistee Street site: Table 4.10 — EB 1696 at Manistee 6 am. to 7 am. Diversion Confidence Intervals The results are shown in Tables 4.10-4.12 for the eastbound 196 at Significance Level Diversion Confidence Interval 99% 1.865, 1.895 98% 1.868, 1.892 95% 1.871, 1.889 37 Table 4.11 — EB 1696 at Manistee 7 am. to 8 am. Diversion Confidence Intervals Significance Level Diversion Confidence Interval 99% 2.190, 2.470 98% 2.220, 2.450 95% 2.240, 2.420 Table 4.12 -— EB 1696 at Manistee 8 am. to 9 am. Diversion Confidence Intervals Significance Level Diversion Confidence Interval 99% 1.830, 2.210 98% 1.870, 2.170 95% 1.920, 2.130 The freeway incident data were reviewed for accidents that occurred at or beyond the exit limits of the site, possibly producing a traffic backup. Since there were no accidents reported for this site during the months of November and December (1998), an analysis of the statistical data based upon an accident occurrence with no CMS display could not be completed for this site. Westbound 1-96 at Buchanan The diversion ratios for the westbound I-96 at Buchanan Street site for the peak three- hour aflemoon travel period are recorded in Table 4.13 and shown graphically in Figure 4.03: 38 Table 4.13 — WB 196 at Buchanan PM. Peak Period Diversion Ratios Date Time (p.m.) Ratio Mainline Ramp Exit Mean Exit Volume Volume Mainline Exit Speed Onph) 11/17/98 4100-5200 4.40 4981 1133 69 11/18/98 4:00-5:00 4.77 5075 1065 70 , 12/08/98 4:00-5z00 *7.40 5190 701 68 12/09/98 4:00-5200 4.38 5416 1236 69 12/10/98 4:00-5:00 4.39 5243 1193 67 11/17/98 5 :00-6:00 4.73 4581 968 67 11/18/98 5:00-6:00 4.68 4717 1008 68 12/08/98 5:00-6:00 *7.20 4910 682 65 12/09/98 5 :00-6:00 4.48 4579 1023 67 12/10/98 5 :00-6:00 4.36 4818 1105 66 11/17/98 6:00-7:00 3.24 2592 800 66 11/18/98 6:00-7:00 3.45 2452 710 69 12/08/98 6:00-7:00 *5.55 2625 473 68 12/09/98 6:00-7:00 3.25 2487 766 68 12/10/98 6 :00-7:00 3 .27 2495 763 68 5 . 0 - A m 4.5 g X X! \\ NEAN Dun} ‘ «‘3 RATI 0 L1. 0 l 3.5. l (j/t,‘ ..... 3 . 0 u 4-5 4-5 5-6 5-6 6-7 6-7 6-7 PEAK PERIOD u p.m. T0 7 p.m. Figure 4.03 - WB 196 at Buchanan — Ratio of 196 to 194 Traffic Volumes 39 *Based upon a review of the consistency of the data shown in Table 4.13, ratio computations for the date of 12/08/98 for the time period of 4:00 p.m. to 7 :00 p.m. will be rejected. The presumption is that either an incident occurred at this time or the data for this date and time period were not accurate due to an equipment malfunction. Similar to the first two sites, the t statistic was used to calculate the 95%, 98% and 99% confidence levels. The results are shown in Tables 4.14 and 4.15 for the westbound 196 at Buchanan Site: Table 4.14 - WB 196 at Buchanan 4 p.m. to 6 p.m. Diversion Confidence Intervals Significance Level Diversion Confidence Interval 99% 4.30, 4.74 98% 4.34, 4.70 95% 4.38, 4.67 Table 4.15 - WB 196 at Buchanan 6 p.m. to 7 p.m. Diversion Confidence Intervals Significance Level Diversion Confidence Interval 99% 3.01, 3.59 98% 3.08, 3.53 95% 3.14, 3.47 The freeway incident data were reviewed for accidents which occurred within or near the exit limits of the site, possibly producing a traffic backup. Since there were no accidents reported for this site during the months of November and December (1998), an 40 analysis of the statistical data based upon an accident occurrence with no CMS display could not be completed for this site. Since there were insufiicient data to determine the impact of an incident when no CMS was available to communicate with the motorist, it was not possible to create a base condition from the field data. Therefore, simulation was used to detemrine the impact of diversion on the average travel and delay time of motorists taking each of the two paths available at the diversion point. The results of the simulation analysis can be used for two purposes. The first is to determine the extent of diversion required to have a measurable impact on the measures of effectiveness selected for the study. The second is to gain an appreciation for the negative impact of diverting traffic when there is no incident, or the incident is of short duration. Simulation Analysis of Travel Timnd Delay An analysis was completed for each study site to determine the impact of changes in the volume ratio on driver delay. The FRESIM trafiic simulation program was used to analyze the original traffic volumes, and the volumes when an additional 10% or more of the drivers who would normally continue to travel on the freeway, choose the ramp exit. Simulation analysis was also completed to determine the impact on delay, speed and travel times when 10% or more of the drivers who would normally divert to the ramp exit, chose to remain on the mainline freeway. Based upon data retrieved for each site, the hour with the highest trafiic volume was determined for each site. The data for this hour were used as input into the simulation 41 program to determine the values of the measures of effectiveness during normal conditions. The morning peak hour for the eastbound [-696 at Manistee site was determined to be 6:45 am. to 7:45 am. when the total volume is 7752 vehicles per hour. The traffic volumes utilized in each of the three simulation cases for this site are shown in Table 4.16. Ten computer simulations were run for the existing and each of the 10% diversion analyses, with a different random seed for each case. The simulated results of the measures of effectiveness for the existing and diversion conditions during this peak travel period are as follows: Eastbound I-96 at Manistee Street The traffic volumes and simulation results for the existing condition and 10% diversion alternative in each direction are presented in Tables 4.16 to 4.19. Once again, ten runs were made using a different random number seed for each run. Table 4.16 Simulation Volumes — EB 1696 at Manistee Street Diversion Total Total Case Mainline Ramp Exit Exit Volume Volume Existing 5301 2451 10% Ramp 4771 2981 10% Freeway 5 83 l l 921 42 Table 4.17 — Simulation Measures of Effectiveness — Existing Volumes AM. Peak (6:45 a.m.-7:45 am.) — EB 1696 at Manistee Street TRIAL DELAY DELAY AVERAGE AVERAGE (VEH-MINS/ (VEH-MINS/ TRAVEL TRAVEL VEH-MILE) VEH-MILE) TIME TIME 1-696 I-75 (VEH-MINS) (VEH-MINS) 0.41 MILES 0.42 MILES I-696 [-75 l .10 .13 439.1 232.6 2 .ll .15 446.0 225.3 3 .11 .11 441.2 227.0 4 .12 .13 434.7 238.2 5 .11 .11 438.4 227.1 6 .11 .14 433.8 238.0 7 .12 .13 433.5 237.8 8 .ll .15 432.8 240.1 9 .10 .14 429.8 241.4 10 .10 .13 412.6 262.9 AVG. .11 .13 434.2 237.04 Avg. Travel 23.64 seconds 28.66 seconds Time Table 4.18 — Simulation Measures of Effectiveness —10% Diversion to Ramp AM. Peak (6:45 a.m.-7:45 am.) — EB 1696 at Manistee Street TRIAL DELAY DELAY AVERAGE AVERAGE (VEH-MINS/ (VEH-MINS/ TRAVEL TRAVEL VEH-MILE) VEH-MILE) TIME TIME 1-696 1-75 (VEH-MINS) (VEH-MINS) 0.41 MILES 0.42 MILES [-696 1-75 1 .10 .17 390.7 290.9 2 .11 .15 397.5 280.2 3 .12 .17 400.9 231.2 4 .11 .17 396.4 285.8 43 5 .11 .17 393.2 290.7 6 .10 .15 406.6 269.0 7 .12 .15 386.9 295.7 8 .10 .16 393.0 287.9 9 .10 .15 399.4 277.5 10 .13 .16 406.8 279.1 AVG. .11 .16 397.14 273.80 Avg. Travel 24.34 seconds 27.41 seconds Time Diverting an additional 10% of the traffic to the ramp to 1-75 did not have significant impact on vehicle delay. Table 4.19 - Simulation Measures of Effectiveness —10% Diversion to Mainline Freeway AM. Peak (6:45 a.m.-7:45 am.) - EB I696 at Manistee Street TRIAL DELAY DELAY AVERAGE AVERAGE (VEH-MINS/ (VEH-MINS/ TRAVEL TRAVEL VEH-MILE) VEH-MILE) TIME TIME I-696 1-75 (VEH-MINS) (VEH-MINS) 0.41 MILES 0.42 MILES I-696 [-75 l .10 .10 471.8 187.5 2 .10 .13 468.7 193.9 3 .ll .10 473.7 187.4 4 .10 .13 459.7 200.8 5 .11 .10 477.5 180.2 6 .12 .12 486.1 176.0 7 . 10 . 12 470.6 189.0 8 .12 .12 482.4 178.6 9 .10 .11 483.2 174.4 10 .ll .13 480.3 178.2 AVG. .11 .1 1 475.4 184.60 Avg. Travel 24.33 seconds 27.18 seconds Time 44 The delay and average travel time results reveal that a 10% diversion from either route to the alternative route has little impact on average travel times or delay on either route. This is primarily because the congestion formed on the weaving area link, regardless of which of the two exit paths, experiences delay. Westbound I-96 at Buchanan Street The afiemoon peak hour for the westbound I-96 site was determined to be 4:35 p.m. to 5:35 p.m. The traffic volumes and simulation results for the existing condition and each of the diversion alternatives are presented in Tables 4.20 to 4.23. Table 4.20 Simulation Volumes — WB 196 at Buchanan Street Diversion Total Total Case Mainline Ramp Exit Exit Volume Volume Existing 5446 1048 10% Ramp 4901 1593 l 0% Freeway 5991 503 Table 4.21 - Simulation Measures of Effectiveness - Existing Volumes PM. Peak (4:35 p.m.-5:35 p.m.) - WB 196 at Buchanan Street TRIAL DELAY DELAY AVERAGE AVERAGE (VEH-MINS/ (VEH-MINS/ TRAVEL TRAVEL VEH-MILE) VEH-MILE) TIME TIME I-96 1-94 (VEH-MINS) (VEH-MINS) 0.67 MILES 0.27 MILES I-96 1-94 1 .06 .12 736.6 72.8 2 .06 .11 750.2 66.6 3 .06 .12 768.7 59.5 45 4 .06 .14 755.3 66.3 5 .06 .13 752.6 67.5 6 .06 .16 747.8 69.6 7 .06 .16 728.5 77.3 8 .07 .14 767.0 60.1 9 .06 .12 760.8 62.3 10 .06 .12 729.5 77.1 AVG. .06 .13 749.70 67.91 Avg. Travel 39.25 seconds 18.27 seconds Time Table 4.22 - Simulation Measures of Effectiveness —10% Diversion to Ramp PM. Peak (4:35 p.m.-5:35 p.m.) - WB 196 at Buchanan Street TRIAL DELAY DELAY AVERAGE AVERAGE (VEH-MINS/ (VEH-MINS/ TRAVEL TRAVEL VEH-MILE) VEH-MILE) TIME TIME [-96 I-94 (VEH-MINS) (VEH-MINS) 0.67 MILES 0.27 MILES I-96 [-94 1 .06 .14 681.1 99.9 2 .06 .12 681.4 99.3 3 .06 .15 679.0 101.0 4 .06 .16 673.0 103.1 5 .06 .15 672.0 104.1 6 .05 .14 678.1 99.4 7 .06 .14 674.8 102.1 8 .06 .14 677.1 100.8 9 .05 .13 691.0 95.4 10 .06 .18 662.4 109.2 AVG. .06 .145 676.99 101.43 Avg. Travel 39.24 seconds 18.35 seconds Time 46 Table 4.23 - Simulation Measures of Effectiveness —10°/o Diversion to Mainline Freeway PM. Peak (4:35 p.m.-5:35 p.m.) - WB 196 at Buchanan Street TRIAL DELAY DELAY AVERAGE AVERAGE (VEH-MINS/ (VEH-MINS/ TRAVEL TRAVEL VEH-MILE) VEH-MILE) TIL/IE TIME 1-96 1-94 (VEH-MINS) (VEH-MINS) 0.67 MILES 0.27 MILES [-96 [-94 l .06 .12 825.5 31.8 2 .06 .12 810.0 38.5 3 .07 .13 834.4 30.0 4 .07 .18 817.1 38.9 5 .06 .11 838.4 26.9 6 .07 .14 831.6 31.7 7 .06 .12 829.1 31.6 8 .07 .11 819.0 37.5 9 .07 .15 843.4 28.9 10 .06 .15 827.1 32.2 AVG. .065 .133 827.56 32.8 Avg. Travel 39.33 seconds 18.17 seconds Time The results are similar to the first case, with the delay and average travel time changes from a 10% diversion from either route to the alternative route being quite small. Eastbound I-96 East of Beck Road The afternoon peak hour for the eastbound 1-96 site was determined to be 6:25 am. to 7:25 am. when the average total traffic volume is 7408 vehicle per hour. The traffic volumes and simulation results for the existing condition and each of the diversion alternatives are presented in Tables 4.24 to 4.27. 47 Table 4.24 Simulation Volumes - EB [96 East of Beck Diversion Total Total Case Mainline Ramp Exit Exit Volume Volume Existing 4180 3228 10% Ramp 3762 3646 1 0% Freeway 4598 2810 Table 4.25 Simulation Measures of Effectiveness — Existing Volumes AM. Peak (6:25 a.m.-7:25 am.) — EB [96 East ofBeck Road TRIAL DELAY DELAY AVERAGE AVERAGE (VEH-MINS/ (VEH-MINS/ TRAVEL TRAVEL VEH-MILE) VEH-MILE) TIME TIME I-696 I-275 (VEH-MINS) (VEH-MINS) 1.71 MILES 0.95 MILES I-696 I-275 1 .08 .07 1279.3 675.4 2 .08 .06 1377.3 636.9 3 .08 .06 1360.2 645.8 4 .09 .05 1348.5 659.1 5 .08 .06 1373.1 636.4 6 .09 .06 1333.9 665.2 7 .08 .05 1356.3 643.7 8 .08 .06 1370.5 643.7 9 .08 .05 1374.5 631.5 10 .08 .06 1309.4 673.9 AVG. .08 .06 1348.3 651.2 Avg. Travel 100.12 seconds 62.72 seconds Time 48 Table 4.26 - Simulation Measures of Effectiveness - 10% Diversion to Ramp AM. Peak (6:25 a.m.-7:25 a.m.) -— EB [96 East of Beck Road TRIAL DELAY DELAY AVERAGE AVERAGE (VEH-MINS/ (VEH-MINS/ TRAVEL TRAVEL VEH-MILE) VEH-MILE) TIME TIME I-696 I-275 (VEH-MINS) (VEH-MINS) 1.71 MILES 0.95 MILES I-696 I-275 l .08 .06 1247.3 712.2 2 .08 .07 1222.3 735.7 3 .08 .06 1199.0 740.2 4 .07 .07 1244.6 721.0 5 .08 .06 1228.6 729.9 6 .08 .06 1187.9 758.0 7 .08 .06 1260.0 755.0 8 .07 .06 1151.9 774.5 9 .08 .06 1215.8 738.2 10 .08 .06 1227.2 731.8 AVG. .08 .06 1218.46 739.7 Avg. Travel 97.35 seconds 65.27 seconds Time Table 4.27 — Simulation Measures of Effectiveness—10% Diversion to Mainline Freeway AM. Peak (6:25 a.m.-7:25 am.) — EB [96 East of Beck Road TRIAL DELAY DELAY AVERAGE AVERAGE (VEH-MINS/ (VEH-MINS/ TRAVEL TRAVEL VEH-MILE) VEH-MILE) TIME TIME I-696 1—275 (VEH-MINS) (VEH-MINS) 1.71 MILES 0.95 MILES 1-696 1-275 1 .09 .04 1502.4 555.4 2 .09 .06 1500.8 559.9 3 .12 .04 1541.8 541.3 4 .11 .04 1492.4 571.6 49 5 .10 .06 1463.8 582.9 6 .10 .05 1482.4 576.8 7 .08 .04 1468.8 571.1 8 .08 .04 1454.5 579.6 9 .10 .06 1506.7 556.8 10 .10 .05 1484.6 572.7 AVG. .10 .05 1489.82 566.66 Avg. Travel 100.27 seconds 63.14 seconds Time It is obvious from the results that a 10% diversion from either route to the alternate route has very little impact on average travel times or delay on either route. Thus, under normal conditions, the impact of a false alarm which results in a 10% diversion or less will be minimal, except for any excess travel time consumed in traversing a longer path to the drivers’ ultimate destination. Sensitivity of Delay to Diversion This site was also simulated to determine the impacts on speed and delay as the percentage of diversion to the ramp and to the mainline increase. Various volumes were simulated to determine the point at which the network becomes congested, resulting in speeds less than 30 miles per hour at the diversion link 104-106 (See Figure 4.04). Based upon this simulation, the speeds on this link begin to show the impacts of congestion when the entry volume exceeds 4700 vehicles per hour. The link-node diagram shown below as Figure 4.04 displays the applicable network link (104-106). 50 EB [96 / 118 110 108 101 102 104 ”2\ 114 \ 116 up To [275 Figure 4.04 — EB [96 East of Beck — FRESIM Link-Node Diagram The resultant speeds and delays on link (104-106) for various percentages of ramp diversion to the exit ramp ranging from 0 to 60 percent are shown in Figure 4.05. Figure 4.06 shows the impact on the same link when diversion is made to the mainline. The speed in miles per hour and delay in seconds per vehicle are shown on the y-axis. Figures 4.05 and 4.06 reveal that the freeway speeds (mph) and delay (sec/veh) along the weaving link are greatly impacted for those drivers attempting to continue their travel along the freeway mainline when there is a significant diversion to their route. 51 180 160 140- SPEED/ DELAY 100- 80- 60', Speed 104—106 LIO- “hm—”I‘m . 20 ‘”‘" SPEED Delay 04-106 0 10.00 20.00 30.00 40.00 50.00 60.00 % DIVERSION TO RAMP DELAY Figure 4.05 — EB [96 East of Beck — Speed and Delay on Weaving Link (104-106) Ramp 11er 120: f 100. ’flxffi MEAN / ‘J/T SPEED p3“ DELAY 80' a!“ "MMWSPEED ||| DELAY 00 10.00 % DIVERSION TO MAINLINE Figure 4.06— EB [96 East of Beck — Speed and Delay on Weaving Link (104-106) Mainline 52 Figure 4.07 shows the resultant delay and speed on I-96 exit link (108-110) based upon an entry volume of 4700 vehicles, and ramp diversion percentages that vary from 0 to 60 percent. These results indicate that the congestion occurs on the link upstream from the diversion point where traffic is changing lanes to successfully exit the freeway. Once the traffic enters the exit ramp, the speed increases to the free flow speed of 65-70 miles per hour. 7O “nan-- M Speed 108—1 10 60 “WW” MEAN 50 88888 30 i 20 Delay 108-1 10 O 10. 00 20.00 30. 00 LL08 OO 50 OO 60. OO % DIVERSION TO RAMP Figure 4.07— EB [96 East of Beck — Speed and Delay at Exit Model Validation A review of the actual speed data for link (108-1 10) for the morning peak hour of 6:25 am. to 7:25 am. shows that the average vehicle velocity was 64 miles per hour, as shown in Table 4.28. 53 Table 4.28 Actual Speed Data 6:25 am. to 7:25 am. -— EB [96 East of Beck Road Actual Time of Day Number Percent of Vehicles Average Of Traveling Greater Mainline Observations than 65 MPH Exit Speed 64 MPH 6:25 am to 7:25 am 610 38.4% To validate the FRESIM simulation model for this project, a comparison of the actual versus simulated mainline speeds for vehicles exiting the network was made using a volume of 7408 entering vehicles as shown in Table 4.24. The simulation was run for the site based on a mainline exit volume of 4180 vehicles and 3228 for the ramp exit volume. The results of the simulation revealed an average mainline exit speed of 61 miles per hour. The difference between the actual and simulated speeds is 4.67 percent. Thus, the model, as calibrated, appears to be a reasonably accurate reflection of the speeds measured in the field. Araalysis of Lane Closure Impact Due to Recurring or Non-Recurring Congestion The 1-96 at Beck Road location was simulated to determine the speed and delay impacts of a one-lane freeway or ramp closure based upon an entry volume of 4700 vehicles per hour. The impacts on weaving link (104-106), I-96 exit link (108-110) and ramp exit link (112-114) were analyzed to determine the network impact in terms of average speed and delay for vehicles in the network. The results shown in Table 4.29 reveal a 27.5 percent decrease in speeds along link 104-106 when one downstream 1-96 lane is closed. Similarly, speeds along this link are decreased by 16 percent when one 54 ramp lane is closed. However, the impacts on the downstream links are different for the two cases, as would be expected. If one lane of [-96 is closed, the speed on this link (108-1 10) is reduced, while the speed on the I-275 ramp (112-114) remains high. The reverse occurs if the lane blockage is on the 1-275 exit ramp. Table 4.29 also reveals the impact when an incident occurs which would cause a lane closure and diversion from the mainline to the ramp, or the ramp to the mainline. Table 4.29 - EB [96 East of Beck Road Recurring/Non Recuning Congestion Analysis Lane Weaving Weaving I-96 Exit [~96 Exit Ramp Ramp Treatment Link Link Link Link Exit Link Exit Link 104-106 104-106 [08-110 108-110 112-114 112-114 Speed Delay Speed Delay Speed Delay Miles/Hr SecN eh Miles/Hr SecN eh Miles/Hr SecN eh All Lanes Open 48.90 21.80 61.10 4.10 62.06 2.50 One 1-96 Lane Blocked 35.44 50.40 19.35 69.10 62.72 2.30 One Ramp Lane Blocked 41.19 35.18 60.15 4.60 27.80 22.40 One [-96 Lane Blocked 10% 35.73 49.60 18.71 70.90 60.83 2.90 Divert to Ramp One 1—96 Lane Blocked 20% 48.52 22.60 19.61 68.00 59.47 3.50 Divert to Ramp One I-96 Lane Blocked 30% 44.42 29.30 23.62 51.70 56.56 4.60 Divert to Ramp One Ramp Lane Blocked 10% 26.38 85.10 57.90 5.80 44.72 10.10 Divert to 1-96 One Ramp Lane Blocked 20% 21.24 117.50 59.18 5.20 52.03 6.20 Divert to [-96 One Ramp Lane Blocked 30% 21.26 117.5 58.16 5.70 49.04 7.90 Divert to 1-96 55 7o- ]LLEV Link 1 12—1 14 60 — H 50 SPEED “TM“‘Wan .f “M'- (MPH) fr”; M ’40 ,2”; 30 Link 104—108 20 , . .M-Mv“"”"”“”mnf Link [08-1 1 O 10 20 3o DIVERSION PERCENTAGE 10._ 0— Figure 4.08—Link Speeds When One Lane of 196 is Closed/Ramp Diversion Increases 7O Link [08-1 10 6 O mum-W 50' WE SPEED (MPH) ff” Link 1 124 14 84., J" .H‘Rx. \Rmm 20! HWEMM‘ Link 1 04-1 06 10 _ _ O 10 20 30 DIVERSION PERCENTAGE Figure 4.09—Link Speeds When One Ramp Lane is Closed/Mainline Diversion Increases 56 The results of this simulation, as shown in Table 4.29 and Figure 4.08, indicate an increase in the speed of traffic on links (104-106) and (108-110) can be achieved if the CMS successfiJlly diverts trafiic to the ramp when there is a lane closure on I-96. If 20 percent of the traffic can be diverted to the ramp, the speed on link (104-106) increases by more than 37 percent, from 35.4 to 48.5 miles per hour, with a 5 percent decrease in the speed of traffic on the ramp link (112-114). If the message on the CMS results in a diversion of 30 percent, the increase in speed on link (104-106) decreases from the 20 percent diversion case due to the increased weaving required on this link, but the speed on link (108-110) is increased by about 30 percent from 19.4 to 23.6 miles per hour. The results of this simulation, as shown in Table 4.29 and Figure 4.09, indicate an increase in the speed of traffic on links (112-114) can be achieved if the CMS successfully diverts traffic to the mainline when there is a lane closure on the ramp to 1-275. If 10 percent of the traffic is diverted to the mainline, the speed on link (104-106) decreases by 35 percent, from 35.7 to 26.4 miles per hour due to the increased weaving, but there is a 61 percent increase in the speed of traffic on the ramp link (112-114) from 27.8 to 44.7 miles per hour. If 20 percent of the traffic can be diverted to the mainline, the speed on link (104-106) decreases even further to 48 percent, from 41.2 to 21.2 miles per hour, with an 87 percent increase in the speed iof traffic on the ramp link (112-114) from 27.8 to 52.0 miles per hour. An increase in diversion to 30 percent does not reduce speeds on the weaving link (104-106), but the speed on 1-96 link (108-110) is decreased by about 3 percent from 60.2 to 58.2 miles per hour due to the heavier volume on this path. 57 Impact of Changeable Message Sign Display Messages on Traffic The CMS message logs were obtained from the Michigan Department of Transportation for the period of November 1998 through June 1999. The message logs were reviewed for dates when messages were displayed at any one of the analysis sites. A thorough review of the message logs revealed two dates when data were available when a priority message was displayed to the motorists. These occurred at the westbound 1-96 at Buchanan Street site on April 7, 1999, and on May 10, 1999 at the eastbound I-96 site east of Beck Road. Westbound I-96 East of Buchanan The message display for this site occurred on Wednesday April 7, 1999. Based upon the message log, a message was displayed at 12:57 p.m. regarding an accident on northbound Chrysler Freeway, which is a major north/south connector for travelers on westbound 1-96. Since this message did not occur in the peak hour, it was necessary to determine the typical volume ratio for the two-hour period to be analyzed (12:55 p.m. to 2:55 p.m.). In addition to the date of the message, ten days within the month of April 1999 were used to determine traffic volumes. Data for the following dates were used for this analysis: 0 Tuesday April 6, 1999 0 Thursday April 8, 1999 0 Tuesday April 13, 1999 0 Wednesday April 14, 1999 0 Thursday, April 15, 1999 58 0 Wednesday, April 21, 1999 0 Thursday, April 22, 1999 — Data measures were analyzed, but ratio was determined to be an outlier and was not used in the confidence limit determination. 0 Tuesday, April 27, 1999 0 Wednesday, April 28, 1999 Thursday, April 29, 1999 An average of the traffic volumes for the ten days was computed to determine the average site speed, along with entrance, exit and ramp volumes. The number of one- minute (by lane) volume observations (N) is noted for each data set within this analysis. Based upon these numerical values, the volume ratios were determined, along with their statistical significance. Table 4.30 displays the information for April 7, 1999 at the site. The computed values of the comparison data are displayed in Table 4.31. Table 4.30 - WB 196 at Buchanan Accident Message Display Analysis Date of Initial Mainline Mainline Ramp Volume Mainline Message Display Entrance Exit Exit Ratio Exit Time Volume Volume Volume Speed N=472 N=472 N=1 18 (mph) 4/7/99 12:57 pm 4936 3282 1682 1.95 69.00 59 Table 4.31 - WB 196 at Buchanan Accident Message Analysis — 12:55 p.m. to 2:55 p.m. Date Mean Mean Mean Ratio Mean Mainline Mainline Ramp Exit Mainline Entry Exit Volume Volume Exit Speed Volume N=480 N=121 (mph) N=480 N=480 4/6/99 4945 3103 1636 1.90 66 4/8/99 4889 3316 1559 2.13 64 4/13/99 4983 3429 1562 2.20 69 4/14/99 5275 3669 1437 2.55 67 4/15/99 5378 3592 1357 2.64 68 4/21/99 5176 3534 1690 2.09 67 4/22/99 5373 3941 1116 *3.53 68 4/27/99 5070 3526 1564 2.25 69 4/28/99 53 70 3 592 1729 2.08 69 4/29/99 524] 3562 1415 2.52 68 Average 5147 3480 1550 2.23 67 The diversion ratio confidence intervals for the time period of 12:55 p.m. to 2:55 p.m. using the dates listed were computed as shown in Table 4.32. The ratio of 1.95 for the accident message display date of April 7, 1999 does not lie within these confidence intervals, indicating that the accident message display impacted the decision of motorists to divert from the freeway. This result is different from that found when the accidents that occurred in November and December (before the CMS were deployed) were analyzed. This indicates the message was effective in diverting traffic. Table 4.32 — WB 196 at Buchanan Ratio Confidence Intervals Significance Level Diversion Confidence Interval 95% 2.04, 2.42 98% 2.00, 2.46 99% 1.96, 2.49 60 Eastbound I-96 East of Beck Road The message display for this site occurred on Monday May 10, 1999. Based upon the message log, the accident message was displayed at 3:44 p.m. regarding an accident on the southbound I-275 freeway, which is a major southbound connector for travelers on eastbound I-96. The typical volume ratio for the two-hour period of 3:40 p.m. to 5:40 p.m. was analyzed. In addition to the date of the message, ten days in the month of May 1999 were used to determine traffic volumes. Data for the following dates were used for this analysis: 0 Monday May 3, 1999 0 Tuesday May 4, 1999 0 Wednesday May 5, 1999 0 Thursday May 6, 1999 0 Tuesday May 11, 1999 0 Wednesday May 12, 1999 0 Thursday May 13, 1999 0 Monday May 17, 1999 0 Wednesday May 19, 1999 0 Thursday May 20, 1999 The average traffic volumes for the ten days was computed to determine the site entrance, exit and ramp volumes. Based upon these numerical values, the volume ratios were determined, along with their statistical significance. Table 4.33 displays the 61 information for May 10, 1999 at the site. The computed values of the comparison data are displayed in Table 4.34. Table 4.33 — EB 196 East of Beck Accident Message Display Analysis Date of Initial Mainline Mainline Ramp Volume Mainline Message Display Entrance Exit Exit Ratio Exit Time Volume Volume Volume Speed N=3 60 N=240 N=240 (mph) 5/10/99 3:44 pm 7262 4157 2445 1.70 69.00 Table 4.34 - EB 196 East of Beck Accident Message Analysis — 3:40 p.m. to 5:40 p.m. Date Mean Mean Mean Ratio Mean Mainline Mainline Ramp Exit Mainline Exit Entry Volume Exit Volume Volume Speed (mph) N=480 N=480 N=121 =480 5/3/99 7177 4062 2934 1.38 68 5/4/99 7653 4280 3211 1.33 68 5/5/99 7993 4365 3366 1.30 68 5/6/99 8200 4551 3406 1.34 68 5/11/99 8121 4767 3337 1.43 68 5/12/99 7907 4712 3595 1.31 68 5/13/99 8592 5002 3654 1.37 68 5/17/99 7867 4071 3419 1.19 68 5/19/99 8679 4786 3823 1.25 67 5/20/99 8502 4445 3709 l .20 68 Average 8069 4504 3445 1.31 68 The diversion ratio confidence intervals for the time period of 3:40 p.m. to 5:40 p.m. using the dates listed were computed as shown in Table 4.35. The diversion ratio of 1.70 for the accident message display date of May 10, 1999 is well outside of these confidence 62 intervals, indicating that the accident message display impacted the decision of motorists to divert. Table 4.35 — EB 196 East of Beck Ratio Confidence Intervals Significance Level Diversion Confidence Interval 95% 1.25, 1.36 98% 1.24, 1.38 99% 1.23, 1.39 The computer simulation analysis of this case revealed a 2.77 percent difference in the travel time based upon a comparison of the average mainline and exit ramp volumes (4504, 3445) and the actual volumes of (4157, 2445) which occurred on the date of the message. If the average ratio of the mainline traffic volume to ramp traffic volumes (1.31) existed on May 10, 1999 there would have been 2,858 vehicles on the ramp and 3,144 vehicles on I-96 during the incident. This means the CMS sign was successful in diverting 22% of the traffic from the I-275 ramp to I-96. The sensitivity analysis (Figure 4.09) showed that a 20 to 30 percent diversion, when there is a ramp lane closure, resulted in a 48% decrease in the speed of traffic on the weaving link (104-106) approaching the separation of traffic destined for I-275 and I-96. The two accidents that occurred at this location on November 17, 1998 and December 7, 1998 before the CMS was operational, showed no diversion. The accident that occurred on May 10, 1999 recorded after the CMS was operational showed a diversion of 63 over 20%. If these results hold true, for other accidents and incidents, it appears that the CMS can have a significant impact on traffic volumes, and thus average speed and delay. 64 CHAPTER 5: RESEARCH SUNINIARY AND CONCLUSIONS This study was designed to evaluate the impacts on travel speed and delay due to the use of changeable message signs at locations where drivers could choose to divert from their typical route of travel. This analysis was completed by simulating selected locations on the Detroit Metropolitan Area freeway network when the freeways diverge to determine the impact of diverting traffic away from incidents. A comparison of the volume ratios on alternative paths for normal traffic conditions and traffic conditions occurring within two hours after an incident when no CMS message was displayed to motorists was made. The volume ratios for each case was within the confidence intervals for the existing ratios, indicating that the accident occurrences had no statistically significant impact on the motorists’ propensity to divert from their planned course of travel. By using the FRESIM computer simulation model to determine travel time and delay based traffic diversion. It was determined that to have a significant impact on travel time, the CMS will have to cause a diversion of at least ten percent, and the impact is increased substantially if the diversion is twenty or thirty percent. Diversion to the mainline and ramp were simulated for the weaving link and mainline exit link to show the potential impact on speed and delay as the percentage of the diversion increases to the ramp or mainline. Simulation analysis was also completed to compare speed and delay when a freeway lane closure or diversion is necessary due to recurring or non-recurring congestion. The results of this analysis revealed the potential for speed and delay variances when a driver diverts due to a lane closure. 65 The final analysis consisted of reviewing MDOT message logs to determine the dates and times of CMS messages displayed at the three sites included within this study. Confidence limits for the diversion ratios were developed using real time data for each site. The diversion ratio was computed for the date and time of the accident occurrence. In both cases the percent diversion was greater than 10%. The results suggested rejection of the null hypothesis that the accident message display did not impact the decision of motorists to divert from the freeway. Although much of the data for 1998 was unavailable, beginning in 1999 data related to detemtination of the measures of effectiveness for each site was available. Unfortunately, only two incidents that required a priority message for display on the CMS occurred at the times the detector data were available. This limits the conclusions that can be justified by data. This study may serve as a basis of determining changeable message sign impacts by comparing existing diversion volume ratios to those that occur as a result of incidents and changeable message sign information displayed to motorists. 66 APPENDICES 67 APPENDIX A 68 ITRAF 2.0 Bellandra B. Foster EBIQG/Bedk 1 0 25 21 80625 3600 60 8101 101 102 0 4 1 101 102 104 96620 4 1 106 108 110 61200 2 1 106 112 114 30091 2 1 108 110 118 29030 2 1 110 1188102 15000 2 1 112 114 116 20001 2 1 104 106 108 55440 2 93 5544103 5544 110 102 104 106 9510 4 10 114 1168103 20001 2 1 8101 101 118 101 102 11870 106 108 11870 106 112 11870 108 110 11870 110 118 11870 112 114 11870 104 106 11870 1000 102 104 11870 114 116 11870 8101 101 1024700 101 102 1044700 104 106 1082652 1122048 102 104 1064700 106 108 1102652 112 114 1162048 114 11681032048 108 110 1182652 110 11881022652 106 112 1142048 114 116 2 1500 0200 1800 1800 8101 1014700 15 0 101 5280 10000 102 14942 10000 106 21437 10000 108 27557 10500 112 24446 9500 8101 0 10000 118 31960 11500 8102 33960 12500 8103 28446 8700 110 30460 11500 114 26446 9000 116 28446 8800 104 15893 10000 1 69 a 09 99Michigan State Univ. 7781 30 3280 7581 195 195 195 195 195 195 195 210 I} ‘lOl 'l 104 06 < 108 110 112'\ 114 /118 116 Eastbound 196 East of Beck Road FRESIM Link-Node Diagram 70 EB I96 To 1275 Loop Address Listing Site Location EB l-96 / BECK LOOP NUMBER TO 88 l-275ll96 E1 C E20 $8 M-5 GRAND RIVER E3C E4C EXIT SITE EB I-96 E1A E2A E1 B EZB SITE ENTRY EB I-96 E1A EIB E2A E28 E3A E3B 71 HwAddress 459009 459010 45901 1 459012 459779 459780 459779 459780 459524 459524 459525 459525 459526 459526 85.8 8.... - 885 8...). 85 o m 58 :93 .5... m :8... 85 95188885. .828 - 822 88¢ m 3 895:... .5... m... 5... m8... omm .86 - ones. 88¢ m «N mam :9... .5... km. 8... i 885 8a o m 8.. :95 .5... 8.8...” 83.. - 8.2.9.8 8885. 885.86 mzo. o R 8.. :9... .5... k :85. $8.. - 8.388...“ 8885. 88:51:18 mzo< o R 89.9.... .5... 3.35 - i 833w 85 o m 89:93 .5... 363m 85 9:. 888...). 828 - 822 ..m8¢ m 8 m8 :9... .5... 5.3% 38.... - 8.82.8 8885. 385218 ~mo< MN 9 89.9.... .5... 9.3...” i 8.8m :3 o m 39.93 .5... 3. 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Foster WBI96/Buchanan 1 0 10 3600 60 8402 402 404 0 5 402 404 406 28880 5 404 406 408 16600 4 93 1660 406 412 414 04101 1 408 4108404 10000 4 412 4148406 10001 1 406 408 410 26430 4 8402 402 12265 402 404 12265 404 406 12265 1600 406 412 12255 406 408 12265 408 410 12265 412 414 12255 8402 402 404 100 404 406 4085446 4121048 402 404 4065446 8402 4025413 32 8402 4022413 052000 201000 35 0 402 5280 9900 406 9828 10300 408 12471 10700 412 10238 10000 8402 0 9700 8404 15471 10900 8406 13238 9200 410 13471 10800 414 11238 9650 404 8168 10000 1 79 hnwiabah-wla gsumhigan State Univ. 7781 25 25 25 25 0 1 8263 2 3 4 5 25 50 1 53 170 195 195 195 195 195 195 195 195 195 195 210 8402 402 up Westbound I96 at Buchanan FRESIM Link-Node Diagram 404 406 408 ( 412 80 410 414 WB 196 8404 8406 TO I94 Loop Address Listing Site Location we l-96 / BUCHANAN LOOP NUMBER HwAddress TO I-94 W1 C 658945 W2C 658946 EXIT SITE W8 I-96 W1 A 658689 W2A 658690 W3A 658691 W4A 658692 W1 8 658689 W28 658690 W38 658691 W48 658692 SITE ENTRY W8 I-96 W1C FROM N8 l-75 593153 W2C FROM N8 l-75 593154 W3C FROM SB l-75 593155 W4C FROM SB l-75 593156 81 888 : .m o m 8: :33 .2: :5an 888 :8 o m 88:5 .2: 8.25 885 :80. o m 82E: .2: 0:38 886 85 o m 82E: .2: R25 883m 85 o m 825: .2: $5; 888 88 o m 825: .2: :68 888 :8 o m 88 :5 .2: $8on 888 85 o m 88:5 .2: 38R 28: - 8.28:8 8882 88:88 mzo: o R 88:5 .2: $8; 28: - 8.38:8 8882 88:88 mzo: o R 825: .2: 28m; 28: - 85.. o: 88< 8.882 o mm 825: .2: 5.2.; 88: - 8.28:8 8882 88:88 08: 2 E 28 :5 .2: R8; 88: - :8 >85: 8882 o R 825: .2: R8; 88: - 8.38:8 888:2 88:88 08: I 2 88 :S. .2: 3. 6; 88¢ - :80, ES: 88.8 8882 285 Z 2 88:5 .2: m: 5; 88: - 85 EB: 88.8 8882 8.85 I 2 8m :5 .2: 8.8:. 88: - :8 >85: 8882 o R 28 :5 .2: $82 K8: - 8.38:8 8882 88:88 ozo< mm B 82E: .2: 88.2 :8: - :8 >85: 8882 o R 8: :Q: .2: 98.2 KB: - .85: op 88:. 8882 o on m8 :3: .2: 282 $8: - 85: ES: 8882 88.8 0 mm 28:3 .2: 88:2 88: - 8.38:8 8882 88:88 08: w 2 8m :5 .2: 88:2 033 - .85... o: 822. 8882 o 8 82:5 .2: ER :2 $8: - 85... oh 88< 8882 0 mm 28 :33 .2: o: 2 :2 88¢ - 8.888 8882 8.38:8 2:: 28: o R :8 :5. 2:. $8qu 88: - 8.888 8882 8.38:8 2:: :8: o R 8: :33 .2< 85on 88: - .85: 8. 8:3 8882 0 mm 8... :5 2:. 8.3qu 58.: - 85: o: 88:. 8882 o on 28 :3. 2:. 88:9 88: - :8 >85: 8882 o R :8 :5 .2< 86:9 88: - 885 ES: 88.8 888:2 .820 o R 28 :3. .2< Rmnmmuop m8? - 8.88 ES: 88.8 8882 .820 0 mm 28:5 .2< 28qu 88v - 8.38:8 8882 8.888 9:2 ~20: o R 8: :S .2< BR”? 28% >32qu oEoEucE 6nt; :9»: 35 3.288 mg...“ Emu 82 BIBLIOGRAPHY 83 BIBLIOGRAPHY Alexander, G.J . , Research on Environmental Factors A jfecting Human Behavior, Proceedings of the 59th Annual Road School, Purdue University, West Lafayette IN, 1973. Alexander, GI, and Lunenfeld, H., Satisfying Motorists Need for Information, Traffic Engineering, October, 1972. . Some Factors Affecting Reception and Use of Information by Drivers, Public Roads, Volume 37, Number 1, June, 1972. Armstrong, J .D., and Upchurch, J .E., Human Factors Design Considerations For Variable Message Freeway Signs, Journal of Transportation Engineering, Volume 120, Number 2, March/April, 1994. Barfield, W., Haselkom, M., Spyridakis, J., and Conquest, L., Integrating Commuter Information Needs in the Design of a Motorist Information System, Transportation Research Volume 25A, Numbers 2 and 3, 1991. Bolczak, R., Schofer, J .L., and Wilbur, T., Evaluating the Advance Project, The Proceedings of the 1993 Annual Meeting of IVHS America, April 14-17, Washington, DC. Brocken, M.G.M., and Vlist, M.J.M. van der, T rafiic Control with Variable Message Signs, Society of Automotive Engineers, Inc, Vehicle Navigation and Information Systems Conference Proceedings, October, 1991. Burns, E.N., Changeable-Message Signs in Ohio, Highway Research Board, Special Report 129, July, 1971. Safety Benefits From Eflective Directional Signing for Freeway Entrance Ramps, Compendium of Technical Papers, Institute of Traffic Engineers 44th Annual Meeting, Detroit, MI, September, 1974. Case, H.W., and Slade, H., Signing a Freeway to Freeway Interchange (Guide Signs), University of California Institute of Transportation and Traffic Engineering, California Standard Agreement Number 13457, September, 1965. Dewing, W., and Stackhouse, 8., Following Advice From T rafiic Advisories, University of Minnesota, Human Factors Research Laboratory, Report No. MN/RC-94/29, July, 1994. Dudek, Conrad L., Guidelines on the Use of Changeable Message Signs-Summary Report, USDOT/FHWA, Publication #FHWA—TS-9l-002, May, 1991. 84 BIBLIOGRAPHY . Changeable Message Signs, Transportation Research Board, National Research Council, NCHRP Synthesis 61, July, 1979. Durand-Rancher, Y., What Road Traffic Information for What User ’s Reaction? The Effect of Reliable Information on Driver Behavior, Report 93 AT158, 26"1 International Symposium on Automotive Technology and Automation, Aachen, Germany, September, 1993. Firmin, P.E., Bonsall, P.W., and Beaumont, H.C., Drivers’Attitudes to Variable Message Sign Information in London, Institute for Transport Studies, University of Leeds, Leeds, UK, 1998. Fox, J .E. and Boehm-Davis, D., Eflects of Age and Congestion Information Accuracy of Advanced Traveler Information Systems on User Trust and Compliance, Transportation Research Record 1621, TRB, National Research Council, Washington, DC, 1998. 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Klein, L.D., Eflective Incident Management: Best Placement of I TS Equipment, Traffic Technology International, 1997. Koo, R., and Yim, Y., Commuter Response to T raflic Information on an Incident, Transportation Research Record 1621, TRB, National Research Council, Washington, DC, 1998. Kuiken, M.J., Miltenburg, P.G.M., and Winsum, W.V., Drivers’ Reactions to an Intelligent Driver Support System (GIDS) Implemented in a Driving Simulator, 3rd International Conference on Vehicle Navigation and Information Systems, IEEE, September, 1992. Masters, P.H., Blamey, C., O’Brien, W.B., and Kerr, J .A., An Approach to Provision of Real- Time Driver Information Through Changeable Message Signs, First Vehicle Navigation and Information Systems Conference, IEEE, 1989. Nemeth, Z.A., et. al, Changeable Message Signs: A State of the Art Report, Highway Research Board, National Research Council Report #147, Washington, DC, September, 1973. Picha, D.L., Hawkins, H.G., Womack, K.N., and Rhodes, L.R., Driver Understanding of Alternative Traffic Signs, Texas Transportation Institute Paper #970991, 76‘h Annual Meeting, Transportation Board, January, 1997. Pouliot, S.G., and Wilson, E.M., Motorist Information Needs and Changeable Message Signs for Adverse Winter Travel, Transportation Research Board, National Research Council, Transportation Research Record #1403, Washington, DC, 1993. Rowan, N.J., et. a1, Driver Expectancy Checklist: A Design Review Tool, American Association of State Highway Officials, Washington, DC, 1972. Sozio, S., and Russell, A., Signs of the Times, Traffic Technology International, 1997. 86 BIBLIOGRAPHY Spear, E.D., Fog Detectors for Controlling Changeable-Message Signs, Highway Research Board Special Report 129, National Research Council, Washington, DC, July, 1971. Spyridakis, J., Barfield, W., Conquest, L., Haselkom, M., and Isakson, C., Surveying Commuter Behavior: Designing Motorist Information Systems, Transportation Research Volume 25A, Number 1, 1991. Tanabe, J ., Kurauchi, F., and Shimizu, M., Drivers’ Response to Traflic and Travel Information of the Hanshin Expressway, Institute of Urban Transport Planning, Osaka, Japan, 1998. Upchurch J., Thomas, 68., Armstrong, JD, and Baaj, M.H., The Use of Variable Message Signs in Advanced Traffic Management Systems: An Example of Human Factors Considerations in I VHS, Society of Automotive Engineers, Inc., Report #SP-989, May, 1991. Wohlschlaeger, S.D., Factors A flecting Motorist Route Choice and Diversion Potential, Texas Transportation Institute Paper #970968, 76'h Annual Meeting, Transportation Board, January, 1997. Yang, C.Y.D., Frickker, J .D., and Kuczek, T., Designing Advanced Traveler Information Systems from a Driver ’s Perspective: Results of a Driving Simulation Study, Transportation Research Record 1621, TRB, National Research Council, Washington, DC, 1998. Yim, Y., Hall, R., and Weissenberger, S., Traveler Response to T raffic Information in the San Francisco Bay Area, Transportation Research Board Paper #971377, 76th Annual Meeting, Transportation Board, January, 1997. Yim, Y., and anace, J .L., Sirius Evaluation Project: Variable Message Signs and Traflic Behaviour, 1994 International Road Federation Conference Volume 4, Calgary, Albert, Canada, July, 1994. 87 ENDNOTES 88 ENDNOTES l Youngbin Yim, Randolph Hall, and Stein Weissenberger, Traveler Response to Traffic Information in the San Francisco Bay Area, Transportation Research Board, Paper Number 97-1377, 76‘“ Annual Meeting, 1997, Washington, DC, p. 22. 2 Ibid., 14. 3 Asad J. Khattak, Joseph L. Schofer, and Frank S. Koppelman, Factors Influencing Commuters’ En Route Diversion Behavior in Response to Delay, Transportation Research Record Number 1318, Transportation Research Board, National Research Council, Washington, DC, 1991, p. 126. 4 Steven D. Wohlschlaeger, Factors Affecting Motorist Route Choice and Diversion Potential, Transportation Research Board, Paper Number 97-0968, 76th Annual Meeting, 1997, Washington, DC, Abstract. 5 RD. Huchingson and CL. Dudek, Delay, Time Saved, and Travel Time Information for Freeway Traffic Management, Transportation Research Record Number 722, Transportation Research Board, National Research Council, Washington, DC, 1979, pp. 36-40. 6Asad J. Khattak, Joseph L. Schofer, and Frank S. Koppelman, Factors Influencing Commuters’ En Route Diversion Behavior in Response to Delay, Transportation Research Record Number 1318, Transportation Research Board, National Research Council, Washington, DC, 1991, p. 126. 7Asad J. Khattak, Joseph L. Schofer, and Frank S. Koppelman, Factors Influencing Commuters’ En Route Diversion Behavior in Response to Delay, Transportation Research Record Number 1318, Transportation Research Board, National Research Council, Washington, DC, 1991, p. 127. 8 Several researchers have indicated that drivers are more likely to divert to a familiar route, when available. 9 PE. Firmin, P.W. Bonsall, and HG Beaumont, Drivers’Attitudes to Variable Message sign Information in London, Institute for Transport Studies, University of Leeds, Leeds, United Kingdom, p. 6-7. ‘0 Tanabe Jun, Kurauchi Fumitaka, and Shimizu Masatomo, Drivers’ Response to Trafiic and Travel Information of the Hanshin Expressway, Institute of Urban Transport Planning Co., Ltd., Osaka, Japan, pp. 4-8 89 ENDNOTES ” Asad J. Khattak, Joseph L. Schofer, and Frank S. Koppelman, Factors Influencing Commuters ’ En Route Diversion Behavior in Response to Delay, Transportation Research Record Number 1318, Transportation Research Board, National Research Council, Washington, DC, 1991, p. 128. ‘2 R.D. Huchingson and CL. Dudek, Delay, Time Saved, and Travel Time Information for Freeway Traffic Management, Transportation Research Record Number 722, Transportation Research Board, National Research Council, Washington, DC, 1979, pp. 36-40. ‘3 Ibid., 134. l4Youngbin Yim, Randolph Hall, and Stein Weissenberger, Traveler Response to Traffic Information in the San Francisco Bay Area, Transportation Research Board, Paper Number 974377, 76th Annual Meeting, 1997, Washington 00, p. 12. ‘5 Conrad L. Dudek, Guidelines on the Use of Changeable Message Signs—Summary Report, Federal Highway Administration Publication Number FHWA-TS-9l-002, US. Department of Transportation, Ofiice of Research and Development, McLean, Virginia, May 1991, p. I. ‘6 Ibid., 14. '7 Jonathan Upchurch, Gary B. Thomas, Jeffrey D. Armstrong, and M. Hadi Baaj, The Use of Variable Message Signs in Advanced T raflic Management Systems: An Example of Human Factors Considerations in I VHS, Society of Automotive Engineers, Inc., Report Number SP-989, Warrendale, PA, May, 1991, pp. 92-93. 18 W. Janssen and R. Van der Horst, An Evaluation of Different Forms of Variable Route Guidance Messages, TNO Institute for Perception, The Netherlands, ISATA International Symposium on Automotive Technology and Automation, Florence, Italy, May, 1991, p. 598. ‘9 Bruce G. Gray et al., The Design of a Graphics-Based T raffic Information System Based on User Requirements, Human Factors Society, 34th Annual Meeting, Volume 1, Orlando, Florida, 1990, p. 603. 2" Ibid., 605. 21Mark GM. Brocken and Martie J.M. van der Vlist, Traffic Control with Variable Message Signs, Society of Automotive Engineers, Inc., Vehicle Navigation and Information Systems Conference Proceedings, Document P-253, October, 1991, p. 35. 9O ENDNOTES 22 PE. Firmin, PW. Bonsall, and HG Beaumont, Drivers’ Attitudes to Variable Message sign Information in London, Institute for Transport Studies, University of Leeds, Leeds, United Kingdom, p. 3. 23 Ibid., 6-7. 24 PH. Masters et al., An Approach to Provision of Real-Time Driver Information Through Changeable Message Signs, Vehicle Navigation and Information Systems Conference, The Ministry of Transportation of Ontario, 1989, p. 419. 25 Tanabe Jun, Kurauchi Fumitaka, and Shimizu Masatomo, Drivers’ Response to T raflic and Travel Information of the Hanshin Expressway, Institute of Urban Transport Planning Co., Ltd., Osaka, Japan, pp. 4-8 26 PE. Firmin, P.W. Bonsall, and HG Beaumont, Drivers’ Attitudes to Variable Message sign Information in London, Institute for Transport Studies, University of Leeds, Leeds, United Kingdom, p. 3. 27Asad J. Khattak, Joseph L. Schofer, and Frank S. Koppelman, Factors Influencing Commuters’ En Route Diversion Behavior in Response to Delay, Transportation Research Record Number 1318, Transportation Research Board, National Research Council, Washington, DC, 1991, pp. 133-134. 28 Leo D. Klein, Effective Incident Management: Best Placement of I T S Equipment, Traffic Technology International, 1997, pp. 92-94. 29 PH. Masters et al., An Approach to Provision of Real- Time Driver Information Through Changeable Message Signs, Vehicle Navigation and Information Systems Conference, The Ministry of Transportation of Ontario, 1989, p. 419. 3" Ibid., 417. 3‘ Conrad L. Dudek, Guidelines on the Use of Changeable Message Signs-Summary Report, Federal Highway Administration Publication Number FHWA-TS-91-002, US. Department of Transportation, Office of Research and Development, McLean, Virginia, May 1991, p. 1. 91 "lllllllllllllllllllls