Final Scope

Pavement friction data is crucial for assessing and preventing safety-related crashes due to loss of traction and directly affects vehicle control during braking, steering, and acceleration. Its effectiveness is influenced by factors such as road geometry, traffic conditions, pavement characteristics, and weather. By integrating friction data with these variables, transportation agencies can pinpoint high-risk areas and implement targeted safety improvements in their Pavement Friction Management Program (PFMP). Resources like the AASHTO Pavement Friction Guide (2022) and the AASHTO Highway Safety Manual (2014) offer methodologies to evaluate friction demand and compare it with available friction, helping to minimize crash risks and enhance roadway safety.

This AASHTO Guide recommends a network safety analysis as one of the components of a pavement friction management program. For such an analysis, a functional relationship between crashes (or crash risks) and skid resistance is needed, i.e., a safety performance function (SPF) that uses friction and/or texture as one of the safety predictors. The model structure defined for the SPF can differ among DOTs. There is a need to document the different methods and practices used by state DOTs to model safety performance as a function of friction and to integrate this analysis into a comprehensive PFMP.

The objective of this synthesis is to document current and planned state DOT practices incorporating pavement friction characteristics into roadway safety analysis, including pavement friction/texture measurement, associated design processes, safety modeling, and pavement friction management.

Information to be gathered includes (but is not limited to):

• Identify analysis methods used by each state DOT to model safety performance, and whether skid resistance is considered as a safety descriptor, and if that is the case, what is the safety metric used;
• Testing technologies, measurement protocols, analysis techniques, and performance models used to characterize skid resistance (friction and texture) to correlate safety and pavement performance;
• Identify the extent to which DOTs are integrating their PFMP into the broader pavement management system, including prioritization and optimization; 
• Pavement material surface characteristics (e.g., mixture, geometrical, etc.);
• Crash modification factors used in cost/benefit analysis of friction treatments with the safety performance measurements; 
• What has been the outcome (measuring and tracking) of using the models and analysis, reducing fatal and serious injury crashes, including how the outcomes are being assessed; and
• Investigatory friction threshold per friction demand category.

Information will be gathered through a literature review, a survey of state DOTs, and follow-up interviews with selected DOTs for the development of case examples. Information gaps and suggestions for research to address those gaps will be identified.

Information Sources (Partial)

• Flintsch, G.W., et al. (2021). NCHRP Report 964: Protocols for Network-Level Macrotexture Measurement. National Academies of Sciences, Engineering, and Medicine. Washington, DC: The National Academies Press. https://doi.org/10.17226/26225.
• Guide for Pavement Friction, 2^nd Edition, 2022.
• Highway Safety Manual, 1^st Edition, 2010.
• FHWA Technical Advisory T 5040.38: Pavement Friction Management Program.
• FHWA-RC-20-0009 PFM Program Utilizing Continuous Friction Measurement Equipment and State-of-the-Practice Safety Analysis Demonstration.
• NCHRP Synthesis 20-05/Topic 54-10: State Customization of Highway Safety Manual Methods.
• https://connect.ncdot.gov/projects/research/RNAProjDocs/RP2022-05_Final%20Report.pdf
• CHARACTERIZING ROAD SAFETY PERFORMANCE USING PAVEMENT FRICTION, PUBLICATION NO. FHWA SA-23-006

TRB Staff (consultant)
Sandra Q. Larson
Email: slarson@nas.edu

Meeting Dates
First Panel Meeting: March 11, 2025
Teleconference with Consultant: TBD
Second Panel Meeting: November 19, 2025

Topic Panel

Octavio Eduardo Acevedo, Pennsylvania Department of Transportation

Georgene Malone Geary, GGfGA Engineering

Charles Slone, Ohio Department of Transportation

Mir Tamim, Idaho Transportation Department

Guangming Wang, Florida Department of Transportation

Andy Mergenmeier, Engineer Federal Highway Administration (FHWA)