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Addressing Bicycle-Vehicle Conflicts with Alternate Signal Control Strategies

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Sirisha Kothuri, Portland State University

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Addressing Bicycle-Vehicle Conflicts with Alternate Signal Control Strategies

  1. 1. Addressing Bicycle-Vehicle Conflicts with Alternate Signal Control Strategies Sirisha Kothuri, Andrew Kading, Andrew Schrope Portland State University Edward Smaglik, Christopher Aguilar, William Gil Northern Arizona University NITC Webinar 10/16/2018
  2. 2. Agenda • Introduction • Motivation • Objectives • Survey • Simulation • Field Data Collection • Recommendations • Future Work 2
  3. 3. Right/Left Hook Conflict 3
  4. 4. Motivation 4 ((Source: Hurwitz et al., 2015) Intersection design treatments exist Colored pavement markings Enhanced curb radii Signage Protected intersections Limited research on signal control treatments
  5. 5. Objectives Assess the safety and efficiency impacts of various signal timing treatments that currently exist for right-hook bicycle-vehicle conflicts on all users Traditional phasing LBI Exclusive Phasing Split LBI (Emerging treatment) Field implementation of Split LBI treatment and evaluation of impacts 5
  6. 6. Leading Bike Interval (LBI) 6 Source: MassDOT
  7. 7. Split Leading Bike Interval 7 Source: MassDOT
  8. 8. Exclusive Bike Phase 8
  9. 9. Methodology 9 Comprehensive Review of Conflict Treatments and Practitioner Survey SITL Simulation of Alternate Control Treatments Deployment and Field Data Collection SSplit LBI Implementation in NYC Source: NYCDOT
  10. 10. Survey 10
  11. 11. Survey Respondents 11 Engineer 65% Planner 18% Researcher 4% Other 13% n=69
  12. 12. Awareness of Split LBI 12 Yes 52% No 46% Unknown 2%
  13. 13. Control Strategy Implementation 13 0 5 10 15 20 25 30 Protected Bike Phase LPI LBI Split LBI None Responses(#)
  14. 14. Simulation 14
  15. 15. Simulation Locations 15
  16. 16. LBI 16
  17. 17. Split LBI 17
  18. 18. Exclusive Bicycle Phase 18 Movement Base Case (sec) EBP (sec) % Difference EB TH 17.2 21.68 26% EB RT 5.15 5.52 7% EB LT 62.5 74.52 19% WB TH 22.28 21.23 -16% WB RT 22.16 19.26 -13% WB LT 52.23 56.25 8% SB TH 34.12 35.15 3% SB RT 6.12 6.7 -1% SB LT 54.81 65.81 20% NB TH 37.1 37.64 1% NB RT 7.4 7.77 5% NB LT 53.1 54.74 3%
  19. 19. Summary • LBI • Increase in delay for the through and right-turning vehicles • Split LBI • Increase in delay for the right turning vehicles • No change in delay for the through vehicles • Exclusive Bike Phase • Increase in delay for one approach • Decrease in delay for the other approach (due to coordination) 19
  20. 20. Field Data Collection 20
  21. 21. Field Data Collection Initial Intent: Observe sites before/after LBI or Split LBI addition to develop quantitative guidance What actually happened: We analyzed video of a variety of sites and provided mostly qualitative guidance Metrics: PET Value Time Since Bicycle Green Speed Evasive Action Taken Braking Swerving Changing Lanes 21
  22. 22. Example Video Reduction 22
  23. 23. Time Stamp 23
  24. 24. PET • Post Encroachment Time is “the time from the end of encroachment to the time that the through vehicle actually arrives at the potential point of collision” • A minimum value of PET of 2 seconds would achieve safety benefits, and a PET of less than 2 seconds would result in an interaction and a risk of a collision at signalized intersections (Tang and Kuwahara, 2011; Hurwitz et al. 2015). 24
  25. 25. How is it Calculated? 25 T1 T2 T1 PET= T2 – T1 < 2sec
  26. 26. Severity Metrics 26 PET Value Type of Interaction Very Dangerous Interaction Dangerous Interaction Mild Interaction No Interaction
  27. 27. Data Collection 27 Before After Dates Hours 1st Av and 61st St NA Split LBI 3/6/17 10:30 AM – 7:30 PM 2nd Av and 74th St NA Mixing Zone 5/18/17 8 AM – 7 PM 6th Av and 23rd St Concurrent with a LPI Split LBI 6/7/16 2/20/17 8 AM – 7 PM 7 AM – 6 PM 12th St and Campbell Concurrent LBI 9/19/17- 9/25/17 8 AM – 8 PM Grand and Multnomah NA Mixing Zone 7/10/17 7 AM – 7 PM
  28. 28. Concurrent with LPI 28
  29. 29. 6th Ave and 23rd St Geometry 29 Start of Cycle
  30. 30. 6th Ave and 23rd St (with LPI) 30 Start of Cycle
  31. 31. 6th Avenue and 23rd Street (w/ LPI) Multiple Bicycles and Vehicles Interact
  32. 32. 6th Ave and 23rd St Summary 32 Number of Bicycles 1952 Number of Motor Vehicles 1034 Number of Incidents 443 Percentage of Incidents Based on Number of Bicycles Near Misses 8 Number of Collisions if No Evasive Action Taken 147
  33. 33. 6th Ave and 23rd St Interaction Summary 33 Interaction Type Total Incidents Percentage of Total Incidents Very Dangerous Interaction 142 Dangerous Interaction 129 Mild Interaction 134 No Interaction 28
  34. 34. 6th Ave and 23rd St with LPI Summary • Taxi drivers park on the bicycle lane often to pick up people causing bicycles to go around them • Massive queue build up in every cycle • Bicycles start moving during the pedestrian walk phase • Right turning vehicles back up the queue due to not having an exclusive turning lane, and waiting for pedestrians to cross. 34
  35. 35. Split LBI 35
  36. 36. 1st Ave and 61st St Geometry 36
  37. 37. 1st Ave and 61st St Summary 37 Number of Bicycles 1166 Number of Motor Vehicles 1619 Number of Incidents 445 Percentage of Incidents Based on Number of Bicycles Near Misses 11 Number of Collisions if No Evasive Action Taken 197
  38. 38. 1st Ave and 61st St Interaction Summary 38 Types of Interactions Total Incidents Percentage of Total Incidents Very Dangerous Interaction 272 Dangerous Interaction 142 Mild Interaction 29 No Interaction 2
  39. 39. Elapsed Time since Green 39 Lead Interval = 8 sec
  40. 40. 6th Ave and 23rd St Geometry 40
  41. 41. 6th Ave and 23rd St (After) 41 Interactions
  42. 42. Summary Statistics 42 Number of Bicycles 1300 Number of Motor Vehicles 773 Number of Incidents 221 Percentage of Incidents Based on Number of Bicycles Near Misses 0 Number of Collisions if No Evasive Action Taken 46
  43. 43. 6th Ave and 23rd St Interaction Summary Types of Interactions Total Incidents Percentage of Total Incidents Very Dangerous Interaction 94 Dangerous Interaction 51 Mild Interaction 58 No Interaction 18 43
  44. 44. 6th Ave and 23rd St (After) 44 Lead Interval = 7 sec
  45. 45. Split LBI – Overall Findings 45 • With a Split LBI, the risk is shifted to the stale green • Conflicts are significantly higher at 1st Ave and 61st St compared to 6th Ave and 23rd St. • Higher levels of turn volumes • Downhill grade • Crossing pedestrians impact (?) • What can we do? • Increase the lead interval • Coordinate with adjacent signals, so that most bicycles go through the lead interval (bicycle green wave) • When turn volumes are high, separate the phases
  46. 46. Ranking of Strategies by Vehicular Efficiency 46 Concurrent Phase Mixing Zone Split LBI LBI Exclusive Bike Phase Efficiency
  47. 47. Which Strategy to Choose? 47 Vehicle Turning Volumes BikeVolumes Exclusive Bike Phase Concurrent Split LBI/LBI Mixing Zone Low High LowHigh
  48. 48. Strategy Desirability by Vehicle Turning Volumes 48 Exclusive Bike Phase Split LBI/LBI Mixing Zone Concurrent Phase High Low
  49. 49. Conclusions/Recommendations • Concurrent timing is best suited for low bicycle and low turning vehicle volumes • Right hook potential exists throughout green • LBI / Split LBI are suitable when bike / turning vehicle volumes are medium-high • Split LBI is more efficient, but requires additional signage without RTOR prohibition • Right hook potential moved towards stale green • Bike coordination can further reduce this risk 49
  50. 50. Conclusions/Recommendations • Exclusive Bike Phase is recommended with high bicycle and high motor vehicle volume • Delay is greatest, but conflicts removed 50
  51. 51. Future Work • Supplement surrogate safety data with crash data for further investigation into safety impacts of treatments • Determine volume thresholds for application of various treatments (currently working on this) • Examine gap acceptance of cyclists in various cities, and its relation to safety perception • Quantify impact of pedestrian volumes on strategies 51
  52. 52. Vehicle-Bicycle Conflicts vs. Hourly Bike and Turning Vehicle Volumes 52 0 20 40 60 80 100 120 140 25 50 75 100 125 150 175 200 PredictedVehicle-BicycleConflictsPerHour Thru Bicycles Per Hour Hourly Model Predicted Vehicle-Bicycle Conflicts vs. Hourly Bike and Turning Vehicle Volumes 25 turning vph 50 turning vph 75 turning vph 100 turning vph 125 turning vph 150 turning vph 175 turning vph 200 turning vph
  53. 53. Thank you! Questions? 53 Final Report Link

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