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i CONTENTS Author Acknowledgments ..................................................................... vi Abstract ............................................................................................ vii Summary ............................................................................................ 1 Chapter 1 Background ........................................................................... 4 1.1 Problem Statement ..................................................................... 6 1.2 Research Objectives and Scope .................................................... 7 1.3 Report Organization .................................................................... 7 Chapter 2 Review of the Literature ......................................................... 8 2.1 Introduction ............................................................................... 8 2.2 Summary of PPLT Signal Control Literature .................................... 8 2.3 Driver Comprehension Studies of the Flashing Yellow Arrow ........... 12 2.3.1 Comprehension of the Flashing Yellow Arrow Indication in Various Signal Display Arrangements ............................................ 12 2.3.2 Comprehension of the Flashing Yellow Arrow Indication with Separate Left-Turn Lanes ............................................................ 16 2.3.3 Impact of Flashing Yellow Arrow Indication on the Circular Green Indication .................................................................................. 18 2.3.4 Impact of the Flashing Yellow Arrow Indication on the Steady Yellow Indication ........................................................................ 19 2.3.5 Pedestrian Safety at Intersections with the Flashing Yellow Arrow Indication .................................................................................. 19 2.3.5.1 Driverâs Search for Information ..................................... 21 2.3.6 Comprehension of the Flashing Yellow Arrow Indication after Implementation ......................................................................... 24 2.4 Field Studies of Flashing Yellow Arrow ......................................... 27 2.5 Summary of Literature Review ................................................... 29 Chapter 3 Research Approach .............................................................. 31 3.1 Static Study Development .......................................................... 31 3.1.1 Study Response Data Analysis ............................................. 34 3.2 Dynamic Study ......................................................................... 36 3.2.1 Methodology ..................................................................... 39 3.3 Experimental Results and Data Analysis ....................................... 48 Chapter 4 Findings and Applications ...................................................... 49 4.1 Demographics for Computer-Based Static Study ........................... 49 4.2 Summary of Results for Computer-Based Static Study ................... 49 4.2.1 Summary of Results from Control Scenarios .......................... 49
ii 4.2.2 Summary of Results from Baseline and Experimental Scenarios ................................................................................................ 50 4.2.2.1 Statistical Analysis ...................................................... 50 4.2.3 Flashing Yellow Arrow Indication Location Comparisons .......... 52 4.2.4 Signal Display Comparisons................................................. 53 4.2.5 Thru Indication Comparisons ............................................... 56 4.2.6 Signal Display and Thru Indication Comparisons .................... 59 4.2.7 Opposing Traffic Comparisons ............................................. 59 4.2.8 Demographic Comparisons .................................................. 61 4.2.9 Fail-Critical Comparison ...................................................... 63 4.2.10 Observations from Study ................................................... 63 4.3 Study Demographics for Dynamic Study ...................................... 63 4.4 Summary of Results for Dynamic Study ....................................... 64 4.4.1 Summary of Results from Driving Simulator .......................... 64 4.4.2 Summary of Results from Eye Tracker .................................. 66 Chapter 5 Conclusions and Discussion ................................................... 70 References ........................................................................................ 73 Abbreviations, Acronyms, and Symbols ................................................. 76 APPENDIX A: Static Study Scenario and Response Summary ................... 77 APPENDIX B: Computer-Based Static Study ........................................... 85 APPENDIX C: Screen Shots of Intersections ........................................... 88 APPENDIX D: Vehicle Trajectories ......................................................... 96 APPENDIX E: Box Plot Charts for the Eye Tracking Data .......................... 98 APPENDIX F: Eye Tracker Heat Maps ................................................... 101
iii List of Figures Figure 1. FYA four-section all arrow vertical signal display (Brehmer et al. 2003).................................................................................................. 6 Figure 2. Five-section PPLT signal displays (a) five-section cluster, (b) five- section vertical, and (c) five-section horizontal (Brehmer et al. 2003). ........ 9 Figure 3. Illustration of the yellow trap (MUTCD, 2009). .......................... 11 Figure 4. Scenarios evaluated to analyze the impact of various FYA arrangements (Noyce and Smith 2003). ................................................ 13 Figure 5. Scenarios evaluated to analyze the impacts of simultaneous indications (Knodler et al. 2005). .......................................................... 15 Figure 6. Scenarios evaluated to analyze the impacts of the FYA indication at intersections with wide medians (Knodler et al. 2006-1). ......................... 17 Figure 7. Permissive scenarios evaluated in the driving simulator (Knodler et al. 2006-2). ....................................................................................... 20 Figure 8. Permissive left-turn signal displays evaluated (Knodler and Noyce 2005)................................................................................................ 22 Figure 9. Partitioned driving simulator visual world (Knodler and Noyce 2005)................................................................................................ 23 Figure 10. Example research scenario and question in Missouri (Henery and Geyer 2008). ..................................................................................... 24 Figure 11. Scenarios evaluated to analyze impacts of FYA implementation (Schattler et al. 2013). ........................................................................ 26 Figure 12. FYA signal displays evaluated. ............................................... 32 Figure 13. Practice scenario used in study. ............................................ 34 Figure 14. Example FYA indication and signal display scenario used in study. ........................................................................................................ 35 Figure 15. University of Wisconsin-Madison driving simulator. ................. 37 Figure 16. University of Wisconsin-Madison driving simulator. ................. 37 Figure 17. University of Massachusetts driving simulator. ....................... 38 Figure 18. Wisconsin driving simulator data collection. ........................... 38 Figure 19. Driver simulator study experimental and baseline signal displays. ........................................................................................................ 40 Figure 19 (conât). Driver simulator study experimental and baseline signal displays. ............................................................................................ 41 Figure 20. Screen capture of typical simulated intersection. ..................... 42 Figure 21. Route with module 1. ........................................................... 43 Figure 22. Route with module 2. ........................................................... 43 Figure 23. Route with module 3. ........................................................... 44
iv Figure 24. Eye Tracker on a driver. ....................................................... 47 Figure 25. Depiction of a heat map of driver fixations. ............................. 48 Figure 26 Percentage of correct responses for FYA indication location based on signal display. ................................................................................ 55 Figure 27. Percentage of Fail-critical responses for FYA indication location based on signal display. ...................................................................... 55 Figure 28. Percentage of correct responses for FYA indication location based on thru indication. .............................................................................. 58 Figure 29. Percentage of fail-critical responses for FYA indication location based on thru indication. ..................................................................... 58 Figure 30. Percentage of correct responses in Wisconsin for FYA indication location based on signal display and thru indication. ............................... 60 Figure 31. Summary of eye tracking behavior. ...................................... 66 Figure 32 Sample eye tracking behavior. ............................................... 68 Figure 33. Heat map for five-section cluster signal display with simultaneous FYA and CR indications. ....................................................................... 69 Figure 34. Heat map for three-section vertical signal display with FYA indication. ......................................................................................... 69 Figure B-1: Introduction Screen ........................................................... 85 Figure B-2: Demographic Screen .......................................................... 85 Figure B-3: Practice Screen ................................................................. 86 Figure B-4: Question Screen ................................................................ 86 Figure B-5: Thank You Screen .............................................................. 87 Figure C-1. 62a- 5-Section Cluster FYA Bottom. ..................................... 88 Figure C-2. 57b- 5-Section Cluster FYA Middle. ...................................... 89 Figure C-3. 58a- 5-Section Cluster FYA Bottom. ..................................... 90 Figure C-4. 22- 4-Section Vertical. ........................................................ 91 Figure C-5. 17 or 18- 4-Section Vertical. ............................................... 92 Figure C-6. 17 or 18- 4-Section Vertical. ............................................... 93 Figure C-7. 9b or 10b- 3-Section Vertical FYA Middle. ............................. 94 Figure C-8. 9a or 10a- 3-Section Vertical FYA Bottom. ............................ 95 Figure D-1.Vehicle Trajectories for 9b, 58a, 58b, 17, 9a. ......................... 96 Figure D-2.Vehicle Trajectories for 18, 62a, 62b, 10a, 10b, 22. ................ 97 Figure E-1Average Dwell Duration by Scenario. ...................................... 98 Figure E-2. Dwell Count by Scenario. .................................................... 99 Figure E-3. Total Dwell Duration by Scenario. ...................................... 100
v List of Tables Table 1. Available responses for demographic questions. ......................... 33 Table 2. Example of raw static study data. ............................................. 35 Table 3. Summary of demographic information. ..................................... 49 Table 4. Summary of results based on signal display and FYA section. ...... 51 Table 5. Formatting associated with p values. ........................................ 51 Table 6. Chi-Squared analysis for FYA indication location comparisons. ..... 52 Table 7. Average response time (seconds) based on FYA indication location. ........................................................................................................ 52 Table 8. Chi-Squared analysis for signal display comparisons. .................. 53 Table 9. Average response times based on signal display......................... 54 Table 10. Chi-Squared analysis for FYA indication location based on signal display. ............................................................................................. 54 Table 11. Chi-squared analysis for thru indication comparisons. ............... 56 Table 12. Average response times based on thru movement indication. ..... 57 Table 13. Chi-Squared analysis FYA indication location based on thru indication. ......................................................................................... 57 Table 14. Chi-Squared analysis for opposing traffic comparisons. ............. 59 Table 15. Average response times based on opposing traffic. ................... 61 Table 16. Chi-squared analysis for driving experience comparisons. .......... 61 Table 17. Chi-squared analysis for age comparisons. .............................. 62 Table 18. Average response times based on driving experience. ............... 62 Table 19. Average response times based on age. .................................... 62 Table 20. Summary of demographic information. .................................... 64 Table 21. Summary of Trajectory Data. ................................................. 65 Table A-1. Static study signal display scenarios evaluated (cont.). ........... 78
