Problem Title: Speed Management Solutions and Strategies to Improve Pedestrian and Bicyclist Safety on Arterial Roadways

Background

While the role of speed in traffic crashes is a complex topic, research has found unequivocally that higher speeds lead to higher injury severity for vulnerable road users (Sanders et al., 2019). Notably, the risk of serious injury or fatality for pedestrians increases dramatically as vehicle speed on impact increases, with a roughly 13% change of fatality or severe injury at 20 miles per hour (mph), 40% at 30 mph, and 73% at 40 mph (Tefft, 2013). It is also clear that drivers travelling at higher speeds have less time to react to unexpected situations, less recovery time if distracted, and longer braking distance, which contributes to crashes (Boodlal et al., 2015).

A safe-systems approach to roadway safety requires a robust speed management effort. On lower-volume roadways, traffic calming strategies with vertical and horizontal deflections (raised speed humps, bumps, chicanes, center turning islands) have a been found to be effective at lowering speeds. However, incompatible land uses are often placed next to high speed roadways, and solutions for traffic-speed management along arterials and higher-speed roadways, are more limited and often much more challenging to implement. Research has found that higher-speed arterial roadways are associated with both increased frequency and severity of pedestrian and bicycle crashes (Guerra et al., 2019; Lin et al., 2019). There is some evidence that strategies such as road lane reductions, automated speed enforcement, lane width reductions, speed limit reductions, modifications to traffic signal timing, and well-placed landscaping can reduce vehicle speeds. However, the relationship between lowering vehicle speeds and the magnitude of changes in outcomes for pedestrian and bicycle safety are less clear.

Importantly, although the factors relating to the increased risk of speed to people walking will also apply to people bicycling, few studies specifically link bicyclist or pedestrian injury or fatality risk to speed management directly. In addition, research shows that more active travel lowers risk and while research generally suggests that slower motor vehicle speeds encourage more walking or cycling, there is limited research that quantifies this relationship directly.

Research is needed to 1) demonstrate the impacts of speed management efforts on higher-speed roadways, specifically for people walking and bicycling, and 2) provide clear guidance on successful implementation strategies that have balanced lower speeds for some users with safety improvements for others.

Literature Search Summary

There is a research gap in quantifying the relationship between lowered vehicle speeds and pedestrian and bicycle safety. In recognition of this, there is a NHTSA project underway (Impact of Lowering Speed on Pedestrian and Bicyclist Safety) that has an objective of answering this question. The project is scheduled for completion in 2023. There is a still a need for a case study that demonstrates successful strategies on higher-speed roadways.

Some of the existing research and documents include:

· Sanders, R. L., Judelman, B., Schooley, S. (2019). NCHRP Synthesis 535: Pedestrian Safety Relative to Traffic-Speed Management (01721960; Issue 535). Transportation Research Board. http://www.trb.org/Publications/Blurbs/179827.aspx

· Federal Highway Administration. (2014). Engineering Speed Management Countermeasures: A Desktop Reference of Potential Effectiveness in Reducing Crashes. U.S. Dept. of Transportation. https://safety.fhwa.dot.gov/speedmgt/ref_mats/eng_count/2014/reducing_crashes.cfm

· Neuner, M., Atkinson, J., Chandler, B., Hallmark, S., Milstead, R., Retting, R., Leidos, & Federal Highway Administration. (2016). Integrating Speed Management within Roadway Departure, Intersections, and Pedestrian and Bicyclist Safety Focus Areas (01641642; p. 128p). https://safety.fhwa.dot.gov/speedmgt/ref_mats/fhwasa16017/spd_mgt_rwdpdbik.pdf

Research Objective

The research objective is to produce a guidebook that can be used as a context driven roadmap to speed management on arterial and higher-speed roadways, and how this can be balanced with appropriate safety improvements for pedestrians and bicyclists on these arterial and high-speed roadways. The successful completion of this project, at the minimum, will consist of the following tasks:

· Task 1 – Review literature and state-of-the-practice inventory and information and establish the range of needs and possible case studies regarding development of a context-driven roadmap to speed management on arterial and higher-speed roadways, and how this can be balanced with appropriate safety improvements for pedestrians and bicyclists.

· Task 2 – Develop proposed case studies and information effort covering all aspects of context-driven speed management - roadway design, enforcement, speed limit setting, use of coordinated signal timing in higher speed corridors, self-enforcing roadways, signs, and traffic calming that are appropriate for a range of speeds and road classifications. Also include in the proposal, context-driven case studies and information on safety improvements for pedestrians and bicyclists on arterial and high-speed roadways, including improvements used at varying speeds and improvement costs. Realistically, on some roadways, effective solutions will require greater separation of the modes and this should be addressed in the case studies. Identify the need for any new or additional data.

· Task 3 – Prepare an interim report for review and approval by the project panel documenting the literature review, state of the practice, and proposed case study effort.

· Task 4 – Execute the case study protocol.

· Task 5 - Develop draft case study toolbox of specific recommendations and guidance to implement effective context-driven speed management efforts on arterial and higher-speed roadways, and how these should be balanced with appropriate safety improvements for pedestrians and bicyclists on these arterial and high-speed roadways. This should include details on policies and strategies implemented, how much speeds were reduced, how to balance level of service and safety, safety improvement measures for pedestrian and bicyclists, evidence of improved safety (both perceived and actual), documentation of how travel volumes and delays have changed for all modes.

· Task 6 – Conduct a small user focus group with the draft guidebook to refine the final product.

· Task 7 – Prepare final deliverables and guidelines documenting the research.

Combined with results from the forthcoming NHTSA project, this research wou be a powerful and useful tool for understanding how to make changes that improve active transportation safety

Urgency and Potential Benefits

Over the past decade, pedestrian fatalities have been steadily increasing and are a significant share of the urban transportation safety problem. Bicycle crashes and fatalities are also a concern. Addressing the problem will require a multifaceted context-driven and strategic approach. Reducing speeds, in addition to improving safety, will make many routes more attractive for active transportation. Given the documented relationship between higher-speed roadways and active travel safety and the challenges of managing speed on these roadways, the product of this and other related research is critical to reversing this trend.

Implementation Considerations and Supporters

The guidebook will be of interest and useful to a wide range of traffic engineering, safety and active transportation professionals. The pilot user focus group in Task 6 will provide a template for outreach and additional workshops.

Recommended Research Funding and Research Period

$550,000

2 years

Problem Statement Author(s)

Christopher Monsere, Professor, Portland State University

Sirisha Kothuri, Portland State University

Ryan Martinson, Toole Design Group

AASHTO Council on Active Transportation

Potential Panel Members

Persons Submitting the Problem Statement

Toks Omishakin, Caltrans Director, and Chair of the Council on Active Transportation

References

Agerholm, N., Knudsen, D., & Variyeswaran, K. (2017). Speed-calming measures and their effect on driving speed – Test of a new technique measuring speeds based on GNSS data. Transportation Research Part F: Traffic Psychology and Behaviour, 46, 263–270. https://doi.org/10.1016/j.trf.2016.06.022

Boodlal, L., Donnell, E. T., Porter, R. J., Garimella, D., Le, T., Croshaw, K., Himes, S., Kulis, P., & Wood, J. (2015). Factors Influencing Operating Speeds and Safety on Rural and Suburban Roads. https://trid.trb.org/view/1356043

Federal Highway Administration. (2014). Engineering Speed Management Countermeasures: A Desktop Reference of Potential Effectiveness in Reducing Crashes. U.S. Dept. of Transportation. https://safety.fhwa.dot.gov/speedmgt/ref_mats/eng_count/2014/reducing_crashes.cfm

Fitzpatrick, K., Das, S., Texas A&M Transportation Institute, Safety through Disruption University Transportation Center, & Office of the Assistant Secretary for Research and Technology. (2019). Vehicle Operating Speed on Urban Arterial Roadways (01705749). https://www.vtti.vt.edu/utc/safe-d/wp-content/uploads/2019/04/TTI-01-04_Final-Research-Report.pdf

Hussain, Q., Feng, H., Grzebieta, R., Brijs, T., & Olivier, J. (2019). The Relationship Between Impact Speed and the Probability of Pedestrian Fatality During a Vehicle-Pedestrian Crash: A Systematic Review and Meta-Analysis. Accident Analysis & Prevention, 129, pp 241-249.

Kim, J.-K., Kim, S., Ulfarsson, G. F., & Porrello, L. A. (2007). Bicyclist injury severities in bicycle–motor vehicle accidents. Accident Analysis & Prevention, 39(2), 238–251. https://doi.org/10.1016/j.aap.2006.07.002

Mohit, B., Rosen, Z., & Muennig, P. A. (2018). The impact of urban speed reduction programmes on health system cost and utilities. Injury Prevention, 24(4), pp 262-266.

Mountain, L. J., Hirst, W. M., & Maher, M. J. (2005). Are speed enforcement cameras more effective than other speed management measures?: The impact of speed management schemes on 30mph roads. Accident Analysis & Prevention, 37(4), 742–754. https://doi.org/10.1016/j.aap.2005.03.017

Neuner, M., Atkinson, J., Chandler, B., Hallmark, S., Milstead, R., Retting, R., Leidos, & Federal Highway Administration. (2016). Integrating Speed Management within Roadway Departure, Intersections, and Pedestrian and Bicyclist Safety Focus Areas (01641642). https://safety.fhwa.dot.gov/speedmgt/ref_mats/fhwasa16017/spd_mgt_rwdpdbik.pdf

Rosen, E., Stigson, H., & Sander, U. (2011). Literature review of pedestrian fatality risk as a function of car impact speed. Accident Analysis & Prevention, 43(1), pp 25-33.

Sanders, R. L., Judelman, B., Schooley, S., & National Academies of Sciences, Engineering, and Medicine. (2019). NCHRP Synthesis 535: Pedestrian Safety Relative to Traffic-Speed Management (01721960; Issue 535). Transportation Research Board. http://www.trb.org/Main/Blurbs/179827.aspx

Tefft, B. C. (2013). Impact speed and a pedestrian’s risk of severe injury or death. Accident Analysis & Prevention, 50, 871–878. https://doi.org/10.1016/j.aap.2012.07.022