Left-turning buses: Task analysis, pedestrian collisions and possible solutions

1. Left-turning buses: Task analysis, pedestrian collisions and possible solutions Chia Wei EnsarBecic Christopher Edwards HumanFIRST Program Department of Engineering University of Minnesota

2. Research Background • According to the National Highway Traffic Safety Administration: • One pedestrian fatality event occurred every 2 hours • Someone was injured by a vehicle every 9 minutes • Among fatal events - 24% occurred at intersections • Greater than 40 percent of all fatalities were from pedestrian collisions with transit buses

3. Research Background Left-turns had the highest proportion of pedestrian collisions Buses making left-turns are 4 times more likely to collide with pedestrians compared to drivers who proceed straight through an intersection

4. Research Background Mental workload increases during turning maneuvers at intersections Making a left turn at an intersection requires a greater number of subtasks Bus drivers complete a number of tasks that drivers of other vehicles do not

5. Current Effort • First Step • Examine the cause of pedestrian and bus collision • Metro Transit is creating a safety culture which promotes a zero collision policy • Implemented a Look-and-See campaign to remind drivers to visually scan their surroundings prior to making a left-turn maneuver

6. Current Effort • Overall Goal • Develop a clear picture of various subtasks that bus drivers complete during a left-turn maneuver • Identify potential solutions for the left turn bus-pedestrian conflicts in order to reduce the frequency of collisions • A pilot study examining the efficacy of the proposed solutions

7. First Step - Task Analysis • Create a detailed analysis of various tasks that bus drivers complete when making a left turn • Exogenous • Endogenous • A better understanding of these tasks will facilitate the development of concepts for support tools that help decrease left-turn bus–pedestrian collisions

8. Task Analysis : Methods Study Design: Interviews • Three interviews were completed • Each interview included two bus drivers or driver trainers • Participants were asked to describe all tasks that they perform when making a left turn

9. Task Analysis : Methods As a tool during the interview, several large posters showing intersections were provided for drivers to explain their driving tasks

11. Study One: Study Procedure

12. Study One: Results

13. Task Analysis: Results All of the subtasks and mental processes were classified into these categories • Visual • Broad visual inspection: observe “big picture” • Focused visual search: search traffic lights and mirrors • Working memory • Monitoring a bicyclist • Executive • Determining the gap of an oncoming traffic • Motor tasks • Departing from a previous stop or turning at an intersection • Unplanned events

14. Study One: Results

15. Study One: Study Procedure

16. Study One: Results

17. Study One: Results

18. Task Analysis: Results Other Factors: • Fatigue and stress at work • Maintain strict schedules • Deal with the passengers • Operate the bus safely even in an inclement weather or bad traffic • Visibility: Thunderstorms, blizzard or sun glare • Road Conditions: Large snow banks during winter

19. Next Step – solutions • Bus drivers engage in a large number of different subtasks during left-turns • Solutions • Aiding drivers in performing a particular subtask • Completely removing a need to perform a particular subtask

20. Potential Solutions Technologically Based Solution Aids in the performance of one task Track the movement of targets of interest and alert the driver if a target becomes an imminent danger

21. Study One: Discussion

22. Potential Solutions Infrastructure Based Solution • Removing a need for performing a particular subtask • A protective left-turn for buses — reduce the perceptual and cognitive load.

23. Potential Solutions Environmentally-Based Support Examine the impact of stress on bus driver’s performance and frequency of collisions Poor stress coping = greater driving performance cost in challenging driving conditions

24. Potential Solutions Pedestrian Solution Bus drivers represent only one side of the pedestrian/bus collision Warning alert for a pedestrian Alerting both parties of a collision may improve the odds of collision avoidance?

25. Testing – the Pilot study

26. Pilot Simulator Study Pilot Simulator Study • Objective • Examine the potential efficacy of the proposed solutions

27. Pilot Simulator Study Pilot Simulator Study • Technology Based Solution • Pedestrian Detection System (PDS) • Infrastructure Based Solution • Left Turn Signal • Environmentally Based Support Tool • Two Driving Conditions

28. Pilot Simulator Study Two Driving Condition Groups • Normal Driving Condition • Driving in clear visibility condition • Challenging Driving Condition • Driving in foggy condition • A noisy background • Limited time in which to complete the drive

29. Pilot Study: Methods Driving Simulator

30. Study Two: Study Procedure

31. Pilot Study: Methods • Total of 12 drives • 4 drives included a potential collision scenario

32. Pilot Study: Results • Response to potential collision • Accuracy of Response • The time it took a driver to reduce their velocity by 25%

33. Results Accuracy of Response

34. Results Accuracy of Response

35. Future • Pedestrian Detection Systems • Green Arrow – previously shown benefit, but potential hidden cost • Coping with stressful driving conditions • Alerting pedestrians • Dumb noise • Dynamic alert

36. Thanks! Questions?