American Association of State Highway and Transportation Officials

Special Committee on Research and Innovation

FY2023 NCHRP PROBLEM STATEMENT TEMPLATE

Problem Number: 2023-G-03

Problem Title

Enhancing Highway Safety Manual Guidance on Pedestrian and Bicyclist Countermeasures (CMF/SPF Development)

Background Information and Need For Research

The Highway Safety Manual (HSM) 1st edition provides analytic tools and techniques for estimating the effect of changes to the roadway environment on motor vehicle crash frequency, but provides almost no information on their effects on pedestrian and bicyclist crash frequency. NCHRP Project 17-84, Pedestrian and Bicycle Safety Performance Functions for the Highway Safety Manual, is in the process of developing crash modification factors (CMFs) and safety performance functions (SPFs) for pedestrians and bicyclists in support of a future HSM 2nd edition. However, NCHRP 17-84 is not comprehensive, and the safety benefits of many (especially newer) pedestrian and bicycle countermeasures will still be unknown after the project is completed. Furthermore, established CMFs focused on vehicle-vehicle collisions do not properly account for possibly adverse safety effects for pedestrians and bicyclists or others outside of the vehicle. In addition, the HSM’s CMFs for roadway lighting generally require updating. Without quantifiable safety prediction methods, it can be difficult to justify countermeasure installation, compare and contrast different countermeasure options, or evaluate tradeoffs in vehicular and multimodal safety (e.g., as part of road cross-section reallocation efforts).

Literature Search Summary

The recommendations for future research developed by NCHRP Project 17-84 are expected to be an important input to prioritizing the safety countermeasures to study as part of the work conducted under this activity statement. FHWA’s CMF Clearinghouse contains an up-to-date collection of CMFs, including some that may have been developed by other research being conducted at the same time 17-84 was being conducted. Additionally, NCHRP Project 17-102 focuses on exposure models and safety performance factors that can also serve as input to this project, but are distinct. NCHRP Project 17-72 has developed a CMF rating system that will be used to determine which CMFs come from rigorous-enough studies to be included in the HSM 2nd Edition. This activity should coordinate with ongoing AASHTO and NCHRP research to produce the HSM 2nd edition to avoid duplication of effort. Other work potentially relevant to this research activity includes:

· NCHRP Report 841: Development of CMFs for Uncontrolled Pedestrian Crossing Treatments

· NCHRP Report 893: Systemic Pedestrian Safety Analysis

· NCHRP Report 926: Guidance to Improve Pedestrian and Bicyclist Safety at Intersections

· FHWA-HRT-06-125: Pedestrian and Bicyclist Intersection Safety Indices

· FHWA Proven Safety Countermeasure Program

· TFHRC Crash Modification Factors of Separated Bike Lanes

· Studies and guidance related to ped/bike data quality improvement.

· Ongoing NHTSA research (see reference list)

Research Objective

For alternatives and tradeoffs analyses, continue efforts to quantify 1) the safety performance (crash-reduction effects) of pedestrian and bicyclist safety countermeasures and 2) the pedestrian/bicyclist crash reduction (or expansion) effects of vehicle safety countermeasures, specifically focusing on the highest-priority countermeasures not addressed by NCHRP 17-84 or other research conducted in parallel with 17-84.

This project will produce a guidebook that will include consideration of how treatments focused on addressing the safety or operational needs of one set of roadway users may have different effects on travelers with vision or mobility impairments. Crash-reduction performance is highly important, but not the only factor governing decisions about the specific countermeasure(s) to be installed at a given location. Other guidance documents (e.g., forthcoming NCHRP guidebooks on pedestrian analysis [Project 17-87] and roadway cross-section reallocation [Project 15-78]) will discuss bigger-picture trade-offs involved in decision-making and can be used in conjunction with the findings from this study for countermeasure selection.

Potential tasks include:

· Review the findings and recommendations from NCHRP Project 17-84, when ready, relating to future research priorities for developing CMFs and SPFs for pedestrian and bicyclist safety countermeasures. Review the 17-84 report to identify data collection lessons-learned that should be considered when developing this project’s data collection plan. Review the literature on emerging methodologies that aim to address the limitations of linear models (GLM) in predicting crashes, e.g. systems dynamics models and agent based models

· Conduct a focused literature review on relevant new research published after the 17-84 literature review was developed to help identify what is available and what is still needed. Review pedestrian and bicyclist CMFs added to the CMF Clearinghouse after the 17-84 literature review was developed.

· Prioritize needs for additional CMFs and SPFs for pedestrian and bicyclist safety countermeasures, as well as new methodologies to predict ped/bike safety outcomes, based on what is available and what is still needed.

· Prepare a data collection plan for the selected countermeasures, including consideration of the NCHRP 17-72 rating system, that will maximize the potential that the project will develop CMFs and SPFs with high-enough ratings for inclusion in the HSM. Consider the use of surrogate safety measures to augment sample size.

· Conduct the data collection plan.

· Develop CMFs/SPFs for inclusion in the CMF Clearinghouse and a future HSM update.

· Prepare a final project report summarizing the research findings and providing recommendations for follow-up activities.

Urgency and Potential Benefits

Over the last decade, pedestrian and bicyclist fatalities are increasing as a proportion of overall traffic fatalities, with pedestrian fatalities reaching to highest levels. Estimating the safety performance of countermeasures and their impacts on bicyclists and pedestrians is critically important to improving safety. The outcomes from this study can inform agencies about the safety performance of various countermeasures and will help them make data-driven decisions regarding treatments to improve bicyclist and pedestrian safety.

This research was ranked priority #9 by the AASHTO Committee on Safety.

Implementation Considerations

This research will have value to traffic safety practitioners in all types of organizations and will support and advance efforts to improve pedestrian and bicyclist safety, quantitatively consider pedestrian and bicyclist safety in project decisions, balance crash-reduction and other project considerations, and advance safe system efforts. Implementation efforts should include outreach to potential users of the research products especially at the state and local levels. This could be accomplished in part through collaboration with national associations such as AASHTO, TRB, the National LTAP Association, and others.

Recommended Research Funding And Research Period

$600,000 3 years

Problem Statement Author(S): For each author, provide their name, affiliation, email address and phone.

Laura Mero, Federal Highway Administration, Laura.Mero@dot.gov, (202) 493-3377

Nick Ferenchak, University of New Mexico, ferenchak@unm.edu, (505) 277-0698

Potential Panel Members: For each panel member, provide their name, affiliation, email address and phone.

To be determined.

Person Submitting The Problem Statement: Name, affiliation, email address and phone.

Adnan Qazi, P.E.

Arkansas Department of Transportation

AASHTO Committee on Safety, Research Subcommittee Chair

501-569-2642

Adnan.Qazi@ardot.gov