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NCHRP Web-Only Document 276: Evaluating Strategies for Work Zone Transportation Management Plans Leverson Boodlal Dileep Garimella Kevin Chiang KLS Engineering, LLC Ashburn, VA Steven D. Schrock University of Kansas Lawrence, KS Eric J. Fitzsimmons Kansas State University Manhattan, KS Final Report for NCHRP Project 03-111 Submitted November 2019 NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Systematic, well-designed, and implementable research is the most effective way to solve many problems facing state departments of transportation (DOTs) administrators and engineers. Often, highway problems are of local or regional interest and can best be studied by state DOTs individually or in cooperation with their state universities and others. However, the accelerating growth of highway transportation results in increasingly complex problems of wide interest to highway authorities. These problems are best studied through a coordinated program of cooperative research. Recognizing this need, the leadership of the American Association of State Highway and Transportation Officials (AASHTO) in 1962 initiated an objective national highway research program using modern scientific techniquesâthe National Cooperative Highway Research Program (NCHRP). NCHRP is supported on a continuing basis by funds from participating member states of AASHTO and receives the full cooperation and support of the Federal Highway Administration (FHWA), United States Department of Transportation, under Agreement No. 693JJ31950003. COPYRIGHT INFORMATION Authors herein are responsible for the authenticity of their materials and for obtaining written permissions from publishers or persons who own the copyright to any previously published or copyrighted material used herein. Cooperative Research Programs (CRP) grants permission to reproduce material in this publication for classroom and not-for-profit purposes. Permission is given with the understanding that none of the material will be used to imply TRB, AASHTO, FAA, FHWA, FTA, GHSA, NHTSA, or TDC endorsement of a particular product, method, or practice. It is expected that those reproducing the material in this document for educational and not-for-profit uses will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from CRP. DISCLAIMER The opinions and conclusions expressed or implied in this report are those of the researchers who performed the research. They are not necessarily those of the Transportation Research Board; the National Academies of Sciences, Engineering, and Medicine; the FHWA; or the program sponsors. The information contained in this document was taken directly from the submission of the author(s). This material has not been edited by TRB.
The National Academy of Sciences was established in 1863 by an Act of Congress, signed by President Lincoln, as a private, non- governmental institution to advise the nation on issues related to science and technology. Members are elected by their peers for outstanding contributions to research. Dr. Marcia McNutt is president. The National Academy of Engineering was established in 1964 under the charter of the National Academy of Sciences to bring the practices of engineering to advising the nation. Members are elected by their peers for extraordinary contributions to engineering. Dr. John L. Anderson is president. The National Academy of Medicine (formerly the Institute of Medicine) was established in 1970 under the charter of the National Academy of Sciences to advise the nation on medical and health issues. Members are elected by their peers for distinguished contributions to medicine and health. Dr. Victor J. Dzau is president. The three Academies work together as the National Academies of Sciences, Engineering, and Medicine to provide independent, objective analysis and advice to the nation and conduct other activities to solve complex problems and inform public policy decisions. The National Academies also encourage education and research, recognize outstanding contributions to knowledge, and increase public understanding in matters of science, engineering, and medicine. Learn more about the National Academies of Sciences, Engineering, and Medicine at www.nationalacademies.org. The Transportation Research Board is one of seven major programs of the National Academies of Sciences, Engineering, and Medicine. The mission of the Transportation Research Board is to provide leadership in transportation improvements and innovation through trusted, timely, impartial, and evidence-based information exchange, research, and advice regarding all modes of transportation. The Boardâs varied activities annually engage about 8,000 engineers, scientists, and other transportation researchers and practitioners from the public and private sectors and academia, all of whom contribute their expertise in the public interest. The program is supported by state transportation departments, federal agencies including the component administrations of the U.S. Department of Transportation, and other organizations and individuals interested in the development of transportation. Learn more about the Transportation Research Board at www.TRB.org.
C O O P E R A T I V E R E S E A R C H P R O G R A M S CRP STAFF FOR NCHRP WEB-ONLY DOCUMENT 276 Christopher J. Hedges, Director, Cooperative Research Programs Lori L. Sundstrom, Deputy Director, Cooperative Research Programs Ann Hartell, Senior Program Officer Jarrel McAfee, Senior Program Assistant Eileen P. Delaney, Director of Publications Natalie Barnes, Associate Director of Publications Jennifer Correro, Assistant Editor NCHRP PROJECT 03-111 PANEL Field of TrafficâArea of Operations and Control Chris Ryan Brookes, Michigan DOT, Lansing, MI (Chair) Imad S. Aleithawe, Waggoner Engineering, Inc., Jackson, MS Neil E. Boudreau, Massachusetts DOT, Boston, MA Praveen K. Edara, University of MissouriâColumbia, Columbia, MO Rochelle Hosley, NYS Thruway Authority, Albany, NY Martha C. Kapitanov, FHWA Liaison James W. Bryant, Jr., TRB Liaison .
iv Contents Summary ..................................................................................................................................................... 1 1.0. Introduction ......................................................................................................................................... 4 1.1. Work Zonesâ Effect on Safety ........................................................................................................ 4 1.2. Project Objective .............................................................................................................................. 5 1.3. Report Purpose ................................................................................................................................ 5 1.4. Report Organization ....................................................................................................................... 5 2.0. TMP Strategy Guidebook .................................................................................................................. 7 2.1. Guidebook Contents and Organization ....................................................................................... 7 3.0. Survey Results Regarding the Use and Effectiveness of Individual TMP Strategies .............. 10 3.1. Methodology .................................................................................................................................. 10 3.2. Results ............................................................................................................................................. 11 3.2.1. Demand Management Strategies .......................................................................................... 11 3.2.2. Corridor/Network Management Strategies ....................................................................... 11 3.2.3. Work Zone Safety Management Strategies ........................................................................ 12 3.2.4. Traffic/Incident Management and Enforcement Strategies ............................................ 13 3.2.5. Control Strategies ..................................................................................................................... 13 3.2.6. Traffic Control Devices ........................................................................................................... 14 3.2.7. Public Awareness Strategies .................................................................................................. 14 3.2.8. Motorist Information Strategies ............................................................................................ 15 3.2.9. Project Coordination and Innovative Construction Strategies ...................................... 16 4.0. Selection of Treatments for Field Evaluations .............................................................................. 17 4.1. Initial List of Treatments .............................................................................................................. 17 4.2. Initial List of Treatments Identified for Field Evaluation ........................................................ 18 4.3. Panel Comments on Initial List ................................................................................................... 20 4.4. Final List of Treatments for Field Evaluation ........................................................................... 20 5.0. Field Evaluation of Truck Lane Restrictions ................................................................................. 21 5.1. Site Selection and Characteristics ............................................................................................... 21
v 5.1.1. I-75, Monroe County, Michigan ......................................................................................... 21 5.1.2. US-23, Washtenaw and Livingston Counties, Michigan .............................................. 22 5.2. Study Methodology ...................................................................................................................... 23 5.2.1. Data Collection Duration ..................................................................................................... 23 5.2.2. Data Collection Procedures ................................................................................................. 23 5.2.3. Measures of Effectiveness .................................................................................................... 23 5.2.4. Method for a Statistical Test for the Lane Distribution of Trucks .............................. 24 5.2.5. Method for a Statistical Test for the Truck Speeds ........................................................ 25 5.2.6. Method for a Statistical Test for Frequency of Headways ........................................... 26 5.3. Comparison of Results for Truck Lane Distribution ................................................................ 27 5.3.1. SB I-75 Location ..................................................................................................................... 27 5.3.2. SB US-23 Location ................................................................................................................. 30 5.3.3. NB US-23 Location ................................................................................................................ 32 5.3.4. Combined for All Sites ......................................................................................................... 35 5.4. Comparison of Results for Truck Speeds .................................................................................. 37 5.4.1. SB I-75 Location ..................................................................................................................... 37 5.4.2. SB US-23 Location ................................................................................................................. 38 5.4.3. NB US-23 Location ................................................................................................................ 39 5.5. Comparison of Headways Results ............................................................................................. 40 5.5.1. Comparison of Results for Frequency of Headway ....................................................... 41 5.5.1.1. SB I-75 Location ................................................................................................................... 41 5.5.1.2. SB US-23 Location ............................................................................................................... 44 5.5.1.3. NB US-23 .............................................................................................................................. 48 5.5.2. Comparison of Results for Platoon Headways and Gap Acceptance ........................ 51 5.6. Work Zone Crash Modification Factor for Truck Lane Restrictions ..................................... 55 6.0. Field Evaluation of Temporary Ramp Metering .......................................................................... 57 6.1. Site Selection and Characteristics ............................................................................................... 57 6.1.1. MN Route 52 Bridge Deck Replacement Project, Rochester, Minnesota .................. 57
vi 6.1.2. I-279 Parkway North Improvement Project, Ohio Township, Allegheny County, Pennsylvania .............................................................................................. 60 6.2. Study Methodology ...................................................................................................................... 63 6.2.1. Data Collection Duration ..................................................................................................... 63 6.2.2. Data Collection Procedures ................................................................................................. 63 6.2.3. Measures of Effectiveness .................................................................................................... 63 6.2.4. Method for Statistical Test for Vehicle Speeds ............................................................... 64 6.2.5. Method for Statistical Test for Travel Time through the Work Zone ........................ 64 6.2.6. Method for a Statistical Test for Frequency of Headway ............................................. 65 6.2.7. Driver Compliance of Ramp Meter Signal ....................................................................... 65 6.3. Comparison of Results for Vehicle Speeds ................................................................................ 65 6.3.1 MN Route 52, Rochester, Minnesota .............................................................................. 65 6.3.1.1. Meter-off Scenario vs. Fixed-cycle Length Ramp Metering .......................................... 67 6.3.1.2. Meter-off Scenario vs. Variable-cycle Length Ramp Metering ..................................... 67 6.3.2. I-279, Ohio Township, Pennsylvania ................................................................................ 68 6.3.2.1. Meter-off Scenario vs. Fixed-cycle Length Ramp Metering .......................................... 71 6.3.2.2. Meter-off Scenario vs. Variable-cycle Length Ramp Metering ..................................... 72 6.4. Comparison of Travel Time ......................................................................................................... 75 6.4.1. MN Route 52, Rochester, Minnesota ................................................................................. 75 6.4.1.1. Meter-off Scenario vs. Fixed-cycle Length Ramp Metering .......................................... 78 6.4.1.2. Meter-off Scenario vs. Variable-cycle Length Ramp Metering ..................................... 78 6.4.2. I-279, Ohio Township, Pennsylvania ................................................................................ 79 6.4.2.1. Meter-off Scenario vs. Fixed-cycle Length Ramp Metering .......................................... 82 6.4.2.2. Meter-off Scenario vs. Variable-cycle Length Ramp Metering ..................................... 83 6.5. Comparison of Results for Frequency of Headway ................................................................. 85 6.5.1. MN Route 52, Rochester, Minnesota ................................................................................. 85 6.5.1.2. Meter-off Scenario vs. Fixed-cycle Length Ramp Metering .......................................... 86 6.5.1.3. Meter-off Scenario vs. Variable-cycle Length Ramp Metering ..................................... 87 6.5.2. I-279, Ohio Township, Pennsylvania ................................................................................ 88
vii 6.5.2.1. Right Lane ............................................................................................................................ 88 6.5.2.2. Left Lane ............................................................................................................................... 91 6.6. Network Summary ....................................................................................................................... 95 6.7. Driver Compliance Rates ........................................................................................................... 97 6.7.1. MN Route 52, Rochester, Minnesota ................................................................................. 97 6.7.2. I-279, Ohio Township, Pennsylvania ................................................................................ 97 6.8. Work Zone Crash Modification Factor for Ramp Metering.................................................... 98 7.0 Field Evaluation of Reversible Lanes ............................................................................................ 100 7.1. Site Selection and Characteristics ............................................................................................. 100 7.1.1. I-75, Saginaw County, Michigan ...................................................................................... 100 7.1.2. I-94, Maplewood, Minnesota ............................................................................................ 101 7.1.3. I-75 and I-675, Saginaw and Bay Counties, Michigan ................................................. 102 7.2. Study Methodology .................................................................................................................... 103 7.2.1. Data Collection Duration ................................................................................................... 103 7.2.2. Data Collection Procedures ............................................................................................... 103 7.2.3. Measures of Effectiveness .................................................................................................. 103 7.2.4. Method for a Statistical Test for Vehicle Speeds .......................................................... 104 7.2.5. Method for a Statistical Test for Travel Time through the Work Zone ................... 104 7.2.6. Method for a Statistical Test for Frequency of Headway ........................................... 104 7.3. Field Evaluation Results ............................................................................................................. 104 7.3.1. Location: I-75, Saginaw County, Michigan .................................................................... 104 7.3.1.1. Comparison of Results for Vehicle Speeds .................................................................... 104 7.3.1.2. Statistical Analysis of Vehicle Speed .............................................................................. 111 7.3.1.3. Comparison of Results for Travel Time ......................................................................... 113 7.3.1.4. Statistical Analysis of Travel Time ................................................................................. 116 7.3.1.5. Comparison of Results for Frequency of Headway ..................................................... 117 7.3.2. Location: I-94, Maplewood, Minnesota .......................................................................... 122 7.3.2.1. Comparison of Results for Vehicle Speeds .................................................................... 122 7.3.2.2. Statistical Analysis of Vehicle Speed .............................................................................. 128
viii 7.3.2.3. Comparison of Results for Travel Time ......................................................................... 129 7.3.2.4. Statistical Analysis of Travel Time ................................................................................. 132 7.3.2.5. Comparison of Results for Frequency of Headway ..................................................... 133 7.3.3. Location: I-75 and I-675, Saginaw and Bay Counties, Michigan ............................... 137 7.3.3.1. Comparison of Results for Vehicle Speeds .................................................................... 137 7.3.3.2. Statistical Analysis of Vehicle Speed .............................................................................. 144 7.3.3.3. Comparison of Results for Travel Time ......................................................................... 145 7.3.3.4. Statistical Analysis of Travel Time ................................................................................. 148 7.3.3.5. Comparison of Results for Frequency of Headway ..................................................... 149 7.4. Effects of Reversible Lane Operation on Traffic flow in Work Zones ................................. 152 7.5. Work Zone Crash Modification Factor for Reversible Lane ................................................. 156 8.0. Summary of Findings ..................................................................................................................... 158 8.1. Standalone Guidebook ............................................................................................................... 158 8.2. Field Evaluations Summary of Results .................................................................................... 158 8.2.1. Field Evaluation of Truck Lane Restrictions ................................................................. 158 8.2.2. Field Evaluation of Temporary Ramp Metering .......................................................... 160 8.2.3. Field Evaluation of Reversible Lanes .............................................................................. 162 8.3. Suggestions for Future Research ............................................................................................... 163 References ............................................................................................................................................... 164 Appendix A: Survey Form .................................................................................................................... 165 Appendix B: Strategy Cross-Reference Matrix .................................................................................. 207 NCHRP Web-Only Document 276: Evaluating Strategies for Work Zone Transportation Management Plans is presented in association with NCHRP Research Report 945: Strategies for Work Zone Transportation Management Plans.
ix List of Tables Table 1. Work zone crash factsâfatalities and injuries. ....................................................................... 4 Table 2. Summary of Strategies Considered for Field Evaluation. ................................................... 19 Table 3. SB I-75 Differences in lane distribution without and with truck lane restrictions. ............ 27 Table 4. SB US-23 Differences in lane distribution without and with truck lane restrictions. ........ 30 Table 5. NB US-23 Differences in lane distribution without and with truck lane restrictions. ..... 33 Table 6. Lane distribution differences without and with truck lane restrictions for all sites. ....... 36 Table 7. SB I-75 truck speeds without and with truck lane restrictions. ............................................ 37 Table 8. SB I-75 car speeds without and with truck lane restrictions. ................................................ 38 Table 9. SB US-23 truck speeds without and with truck lane restrictions.......................................... 38 Table 10. SB US-23 car speeds without and with truck lane restrictions. .......................................... 39 Table 11. NB US-23 truck speeds without and with truck lane restrictions. ..................................... 40 Table 12. NB US-23 car speeds without and with truck lane restrictions. ......................................... 40 Table 13. SB I-75 Headway analysis results using K-S testâleft lane. ............................................. 42 Table 14. SB I-75 Headway analysis results using K-S testâright lane. .......................................... 43 Table 15. SB US-23 Headway analysis results using K-S testâleft lane. ......................................... 45 Table 16. SB US-23 Headway analysis results using K-S testâright lane. ...................................... 46 Table 17. NB US-23 Headway analysis results using K-S testâleft lane. .......................................... 48 Table 18. NB US-23 Headway analysis results using K-S testâright lane. ..................................... 50 Table 19. SB I-75 Platoon headways and gap acceptance (3â6 p.m.). ............................................... 53 Table 20. SB US-23 Platoon headways and gap acceptance (6â9 a.m.). ............................................ 53 Table 21. NB US-23 Platoon headways and gap acceptance (3â6 p.m.). .......................................... 54 Table 22. Expected and actual crash results for truck lane restriction. ............................................ 55 Table 23. Crash modification factor results for truck lane restriction. ............................................. 56 Table 24. Speed comparison, meter-off and fixed-cycle length ramp metering.............................. 67 Table 25. Speed comparison, meter-off, and variable-cycle length ramp metering. ...................... 67 Table 26. Speed comparison, meter-off scenario and fixed-cycle length ramp metering (right lane). ............................................................................................................................ 72 Table 27. Speed comparison, meter-off scenario and fixed-cycle length ramp metering (left lane). .................................................................................................................... 72 Table 28. Speed comparison, meter-off scenario and variable-cycle length ramp metering (right lane). ................................................................................................................. 73 Table 29. Speed comparison, meter-off scenario and variable-cycle length ramp metering (left lane). .................................................................................................................... 73 Table 30. Travel time comparison, meter-off scenario and fixed-cycle length ramp metering. .. 78
x Table 31. Travel time comparison, meter-off scenario and variable-cycle length ramp metering. .......................................................................................................................... 79 Table 32. Travel time comparison, meter-off scenario and fixed-cycle length ramp metering (right lane). ..................................................................................................... 82 Table 33. Travel time comparison, meter-off scenario and fixed-cycle length ramp metering (left lane). ........................................................................................................ 83 Table 34. Travel time comparison, meter-off scenario and variable-cycle length ramp metering (right lane). ..................................................................................................... 84 Table 35. Travel time comparison, meter-off scenario and variable-cycle length ramp metering (left lane). ........................................................................................................ 84 Table 36. K-S test results for the meter-on scenarios. .......................................................................... 85 Table 37. K-S test results for the meter-on scenarios (right lane). ..................................................... 88 Table 38. K-S test results for the meter-on scenarios (left lane). ........................................................ 91 Table 39. Expected and actual crash results for ramp metering. ....................................................... 98 Table 40. Crash modification factor results for ramp meter. ............................................................. 99 Table 41. I-75 Reversible-lane operational details. ............................................................................ 101 Table 42. I-75 and I-675 Reversible-lane operational details. ........................................................... 102 Table 43. Speed comparisonânorthbound direction baseline location vs. reversible-lane location. ..................................................................................................................... 111 Table 44. Speed comparisonâsouthbound direction baseline location vs. reversible-lane location. ..................................................................................................................... 112 Table 45. Travel time comparisonânorthbound direction baseline location vs. reversible-lane location. ............................................................................................................... 116 Table 46. Travel time comparisonâsouthbound direction baseline location vs. reversible-lane location. ............................................................................................................... 117 Table 47. K-S test results for the northbound peak direction period. ............................................. 118 Table 48. K-S test results for the southbound peak direction period. ............................................. 120 Table 49. Speed comparisonâ(a.m. peak westbound) without reversible lane vs. with reversible lane. .............................................................................................................. 128 Table 50. Speed comparisonâ(p.m. peak eastbound) without reversible lane vs. with reversible lane. .............................................................................................................. 129 Table 51. Travel time comparisonâ(a.m. peak westbound) without reversible lane vs. with reversible lane. .................................................................................................................................... 132 Table 52. Travel time comparisonâ(p.m. peak eastbound) without reversible lane vs. with reversible lane. .............................................................................................................. 133 Table 53. K-S test results for the a.m. peak westbound direction. .................................................. 134 Table 54. K-S test results for the p.m. peak eastbound direction. ................................................... 135
xi Table 55. Speed comparisonânorthbound direction baseline location vs. reversible-lane location. ............................................................................................................... 144 Table 56. Speed comparisonâsouthbound direction baseline location vs. reversible-lane location. ............................................................................................................... 145 Table 57. Travel time comparisonânorthbound direction baseline location vs. reversible-lane location. ............................................................................................................... 148 Table 58. Travel time comparisonâsouthbound direction baseline location vs. reversible-lane location. ............................................................................................................... 149 Table 59. K-S test results for the northbound peak direction period. ............................................. 150 Table 60. K-S test results for the southbound peak direction period. ............................................. 151 Table 61. Expected and actual crash results for reversible lane ...................................................... 156 Table 62. Crash modification factor results for reversible lane. ...................................................... 157
xii List of Figures Figure 1. Guidebook strategy organization. ........................................................................................... 9 Figure 2. Work zone truck lane restriction. .......................................................................................... 22 Figure 3. SB I-75 Comparison of truck lane distribution during morning peak period (6â9 a.m.). ......................................................................................................................... 28 Figure 4. SB I-75 Comparison of truck lane distribution during mid-day period (10 a.m.â1 p.m.)......................................................................................................................... 29 Figure 5. SB I-75 Comparison of truck lane distribution during evening peak period (3â6 p.m.). ........................................................................................................................ 29 Figure 6. SB US-23 comparison of truck lane distribution during morning peak period (6â9 a.m.). ......................................................................................................................... 31 Figure 7. SB US-23 Comparison of truck lane distribution during mid-day period (10 a.m.â1 p.m.)......................................................................................................................... 31 Figure 8. SB US-23 Comparison of truck lane distribution during evening peak period (3â6 p.m.). ........................................................................................................................ 32 Figure 9. NB US-23 Comparison of truck lane distribution during morning peak period (6â9 a.m.). ......................................................................................................................... 33 Figure 10. NB US-23 Comparison of truck lane distribution during mid-day period (10 a.m.â1 p.m.)......................................................................................................................... 34 Figure 11. NB US-23 Comparison of truck lane distribution during evening peak period (3â6 p.m.). ........................................................................................................................ 35 Figure 12. SB I-75 Cumulative headway distribution plot (left lane)âwithout vs. with condition (6â9 a.m.). ............................................................................................................... 42 Figure 13. SB I-75 Cumulative headway distribution plot (right lane)â without vs. with condition (6â9 a.m.). ................................................................................................ 44 Figure 14. SB US-23 Cumulative headway distribution plot (left lane)â without vs. with condition (6â9 a.m.). ................................................................................................ 45 Figure 15. SB US-23 Cumulative headway distribution plot (right lane)â without vs. with condition (6â9 a.m.). ................................................................................................ 47 Figure 16. NB US-23 Cumulative headway distribution plot (left lane)â without vs. with condition (3â6 p.m.). ................................................................................................ 49 Figure 17. NB US-23 Cumulative headway distribution plot (right lane)â without vs. with condition (3â6 p.m.). ................................................................................................ 51 Figure 18. Ramp-metering data collection locations on MN Route 52 and Route 63 loop b ramp, Rochester, Minnesota. .................................................................................. 59 Figure 19. MnDOT ramp-control signal details. .................................................................................. 60
xiii Figure 20. Ramp-metering data collection locations on I-279 and Union Avenue Ramp, Ohio Township, Pennsylvania. ................................................................... 62 Figure 21. A.M. peak-hour vehicle speed and traffic volumes at Location 3. ................................. 66 Figure 22. A.M. peak hour vehicle speed and traffic volumes at Location 3 (right lane). ............. 69 Figure 23. A.M. peak-hour vehicle speed and traffic volumes at Location 3 (left lane). ............... 70 Figure 24. Hourly volumeâLocation 3, after the merge area. .......................................................... 71 Figure 25. Vehicle speedâLocation 3: After the merge area. ............................................................ 74 Figure 26. A.M. peak hour travel time from Location 1 to Location 3 (distance: 2,800 ft) ............. 76 Figure 27. A.M. peak hour travel time from Location 1 to Location 3, right lane (distance: 5,280 ft). .............................................................................................................. 80 Figure 28. A.M. peak hour travel time from Location 1 to Location 3, left lane (distance: 5,280 ft). ................................................................................................................. 81 Figure 29. Cumulative headway distribution plot, meter-off scenario vs. fixed-cycle length ramp metering (7:30 to 8:30 a.m.). ................................................................ 86 Figure 30. Cumulative headway distribution plot, meter-off scenario vs. variable-cycle length ramp metering (7:30 to 8:30 a.m.). ........................................................... 87 Figure 31. Cumulative headway distribution plot, meter-off scenario vs. fixed-cycle length ramp metering, right lane (7:30 to 8:30 a.m.). ............................................. 89 Figure 32. Cumulative headway distribution plot, meter-off scenario vs. variable-cycle length ramp metering, right lane (7:30â8:30 a.m.). ........................................... 90 Figure 33. Cumulative headway distribution plot, meter-off scenario vs. fixed-cycle length ramp metering, left lane (7:30 to 8:30 a.m.). ................................................ 92 Figure 34. Cumulative headway distribution plot, meter-off scenario vs. variable-cycle length ramp metering, left lane (7:30â8:30 a.m.). .............................................. 93 Figure 35. Volume vs Speed charts (left/right lane) at gore. .............................................................. 95 Figure 36. Network effect. ....................................................................................................................... 96 Figure 37. I-94 cross-section for p.m. peak hour. ............................................................................... 102 Figure 38. Data-collection locations. .................................................................................................... 105 Figure 39. I-75 daily traffic volumes (with reversible-lane change times). ..................................... 106 Figure 40. I-75 hourly traffic volumes (with reversible-lane change times). .................................. 107 Figure 41. Northbound average speed and traffic volumes (10:00 a.m. to 7:00 p.m.). ................. 109 Figure 42. Southbound average speed and traffic volumes (10:00 a.m. to 7:00 p.m.). ................. 110 Figure 43. Northbound travel time (distance: 6.5 mi). ...................................................................... 114 Figure 44. Southbound travel time (distance: 6.5 mi). ...................................................................... 115 Figure 45. Cumulative headway distribution plotânorthbound peak direction periodâbaseline location vs. reversible-lane location (10:00 a.m. to 7:00 p.m.). ...... 119 Figure 46. Cumulative headway distribution plotâsouthbound peak direction periodâbaseline location vs. reversible-lane location (10:00 a.m. to 7:00 p.m.). ...... 121
xiv Figure 47. Data-collection locations. .................................................................................................... 123 Figure 48. I-94 hourly traffic volumes. ................................................................................................ 124 Figure 49. A.M. eastbound average speed and traffic volumes. ..................................................... 126 Figure 50. P.M. eastbound average speed and traffic volumes. ...................................................... 127 Figure 51. A.M. peak westbound travel time (distance: 4.6 mi). ..................................................... 130 Figure 52. P.M. peak eastbound travel time (distance: 4.6 mi). ....................................................... 131 Figure 53. Cumulative headway distribution plotâ(a.m. peak westbound) without reversible lane vs. with reversible lane (6:00 a.m. to 10:00 a.m.). .................................... 135 Figure 54. Cumulative headway distribution plotâ(p.m. peak eastbound) without reversible lane vs. with reversible lane (3:00 p.m. to 7:00 p.m.). ..................................... 136 Figure 55. Data-collection locations. .................................................................................................... 138 Figure 56. I-75 daily traffic volumes. ................................................................................................... 139 Figure 57. I-75 hourly traffic volumes. ................................................................................................ 140 Figure 58. Northbound average speed and traffic volumes. ........................................................... 142 Figure 59. Southbound average speed and traffic volumes. ............................................................ 143 Figure 60. Northbound average travel time (distance: 7.3 mi). ....................................................... 146 Figure 61. Southbound average travel time (distance: 7.3 mi). ....................................................... 147 Figure 62. Cumulative headway distribution plotânorthbound peak direction periodâbaseline location vs. reversible-lane location (12:00 p.m. to 4:00 p.m.). ..... 150 Figure 63. Cumulative headway distribution plotâsouthbound peak direction periodâbaseline location vs. reversible-lane location (12:00 p.m. to 4:00 p.m.). ..... 152 Figure 64. I-75 and I-675 in Saginaw and Bay Counties, Michigan, speed-flow plots ................. 153 Figure 65. I-75 Saginaw County, Michigan, speed-flow plots. ........................................................ 154 Figure 66. I-94 in Maplewood, Minnesota, speed-flow plots.. ......................................................... 155
