Pedestrian Signal Safety for Older Persons

1. Pedestrian Signal Safetyfor Older Persons

2. AAA Foundation for Traffic Safety Established in 1947 501 (c)(3) Not-For-Profit Research affiliate of AAA/CAA North American Focus

3. Mission Identify traffic safety problems Foster research that seeks solutions Disseminate information and educational materials

5. Pedestrian Signal Safety for Older Persons Commissioned by the AAA Foundation Co-Principal Investigators Edward R. Stollof (ITE) Hugh McGee (VHB) Project Manager Kim Eccles (VHB)

6. Background How can a traffic engineer determine the appropriate balance for signal timing for all users at an intersection? Community Objectives Livability Goals Context Sensitive Design/Solutions Understanding of an area’s demographics

7. The Problem 4,881 pedestrians were struck by vehicles and killed in 2005 981 (20%) were 65 and older Approximately 1 in 8 Americans is 65+ U.S. Census Bureau estimates 1 in 5 Americans will be 65+ by 2030 Need to make system safer for older pedestrians

8. Study Goals Measure older and younger pedestrian walking speeds Understand pedestrian behavior at traditional signals and countdown signals Does existing signal timing allow enough time for older pedestrians to cross? Can signal timing be modified to accommodate older pedestrians without causing excessive vehicle delay?

9. Important Note In this study... “older” = 65 years or older “younger” = younger than 65 years

10. Project Objectives Pedestrian Characteristics How does pedestrian behavior differ with respect to: Age Walking Speeds Start-Up Time Persons Left in Intersection Comparison of pedestrian behavior at intersections equipped with: Pedestrian countdown signals Traditional pedestrian signals

11. Methods Literature Review Agency Survey Observational Study Survey of Pedestrians at Study sites CORSIM/Traffic Operations Analysis

12. Key Statistic for Walking Speeds for Older Pedestrians The 15th percentile speed is the generally accepted value to use in timing signals for pedestrians. (as opposed to the Mean Walking Speed)

13. Literature Review Empirical Data on Walking Speeds 15th Percentile Speed for Older Pedestrians Range is 2.20 ft/s to 4.00 ft/s Largest Studies Knoblauch (4,500 pedestrians): 3.08 ft/s Fitzpatrick et. al (2,450 pedestrians): 3.03 ft/s

14. Literature Review Recommended 15th Percentile Walking Speeds for Older Pedestrians Gates ? 20% age 65 and older: 3.6 ft/s ? 30% age 65 and older: 3.5 ft/s ? 40% age 65 and older: 3.4 ft/s ? 50% age 65 and older: 3.3 ft/s 100% age 65 and older: 2.9 ft/s

15. Literature Review Recommended 15th Percentile Walking Speeds (Generalized) Fitzpatrick et al (proportionally weighted, all age groups, above 15 years, for year 2045: 3.56 ft/s Recommendation: 3.50 ft/s

16. Literature Review

17. Literature Review Intersection operations incorporating walking speeds of < 4.0 ft/s will have reduced vehicular delay impacts with: Narrow (shorter) crossings Longer cycle lengths Unsaturated conditions

18. Observational Study 4 intersections each in 6 jurisdictions (24 intersections were analyzed using video) Broward County, Florida Minneapolis-St. Paul, MN Montgomery County, MD Salt Lake City, UT Orange County, CA 1 of 4 intersections in each jurisdiction used as a case study for the traffic operations analysis Comparison group of traditional and countdown pedestrian signals

19. Observational Study

20. Observational Study15th Percentile Walking Speeds

21. So what difference does it make?

22. Example Young pedestrian walking at 4.1 ft/s (reasonable speed from the literature) Older pedestrian walking at 3.4 ft/s (reasonable speed from the literature) When younger pedestrian finishes crossing 70 ft street, older pedestrian still has more than another whole lane to cross.

24. Observational Study Results A clearance interval based on a walking speed of 4.00 ft./sec. would accommodate the 15th-percentile walking speed of younger pedestrians but would not accommodate the 15th percentile older pedestrians. A clearance interval based on a walking speed of 3.50 ft./sec. would accommodate most, but not all of the 15th-percentile older pedestrians in all jurisdictions surveyed.

25. Observational Study Results With sufficient walk time, older pedestrians leaving the curb at the start of the walk interval would be accommodated. A minimum of 3.40 ft./sec. would be needed to accommodate the 15th percentile walking speed for traditional and countdown pedestrian signals in all jurisdictions observed.

26. Intersection Operations Analysis Evaluated the effect of different walking speeds (e.g. 4.0, 3.5 and 3.0 ft/s) to identify the sufficiency of the available green time for each case study intersection. “Green Time” - the maximum time that could be allotted to a pedestrian signal interval based on existing signal timings and phasing.

27. Traffic Operations Analysis Conducted six simulations: Used CORSIM traffic simulation software One simulation in each jurisdiction Complete data was not available in Orange County, CA Developed qualitative/quantitative criteria to assess delay impacts to intersections

28. Traffic Operations Analysis Each case study is different in terms of: Traffic signal cycle lengths Traffic volumes (conducted sensitivity analysis based on existing conditions, reduced demand and increased demand as compared to compared to base conditions) Intersection lane usage

29. What happens to vehicle delay when pedestrians have more time?

30. Intersection Operations Analysis Reducing walking speeds to 3.5 ft/s or even 3.0 ft/s at intersections that operate at LOS “A,” “B,” or “C” would result in insignificant to minor increases in overall vehicular delay. Using a walking speed of 3.5 ft/s at intersections that operate at LOS “D,” “E,” or “F” would result in minor to moderate increases in overall vehicular delay. Using a walking speed of 3.0 ft/s at intersections that operate at LOS “D” or worse would cause a major increase in overall vehicular delay.

31. Intersection Operations Analysis Delay significantly increased when pedestrian times approached or exceeded the available minimum green times for the concurrent phase. Most often occurred on major street approaches Wider approaches (longer crossing distances) increased the pedestrian clearance interval

32. Intersection Operations Analysis Intersections with a better LOS in the base volume condition showed more uniform increases in vehicle delay for each walking speed. Intersections operating closer to capacity in the base condition exhibited exponential increases in vehicle delay.

33. Traffic engineers can modify pedestrian signal timing to accommodate a 7-second WALK interval and a pedestrian clearance interval based on a walking speed of 3.5 ft./sec. with little or no congestion and minimal impacts to vehicle flow (Level of Service A, B or C). At intersections with moderate to significant congestion (Level of Service D, E, or F), moderate to major impacts to vehicle flow would be expected to occur. In this case, prudent traffic engineering judgment will need to be used in achieving a balance between efficient traffic movement and pedestrian accessibility within any given intersection.

34. The U.S. Department of Transportation will take these findings under consideration in the development of the new Section 4.e 10 (pedestrian walking speeds) of the 2009 MUTCD (Manual on Uniform Traffic Control Devices). The U.S. Access Board in their Draft Guidelines for Accessibility within the Public Rights-of-Way [11/23/05] and the National Committee on Uniform Traffic Control Devices (http://www.ncutcd.org) supports the findings and conclusions developed as part of this research.

35. Next Steps There is a need for guidance regarding when to use PCD signals. This current study focused on a few communities that have developed criteria for implementing PCD signals. Most studies are not uniform in their definition of the “older pedestrian”. Older individuals are not one homogenous group. Perhaps, more research is needed based on the health and infirmities of pedestrians at intersections in the development of appropriate intersection walking speeds.

36. Next Steps This study’s scope didn’t specifically investigate the impact of signal timing on blind, low-vision, or otherwise disabled pedestrians and their use of pedestrian-accessible signals. Future studies should convene focus groups to develop parameters of future efforts that would consider the start-up time and walking speed differences of these pedestrian subgroups.

37. For more information, please go to: www.aaafoundation.org