Pavement Project Prioritization using Continuous Pavement Friction Measurement Data

Roadway conditions contribute approximately 34% of typical reported crash causes in the United States. According to the FHWA Safety Office, “Friction is a critical characteristic of a pavement that affects how vehicles interact with the roadway, including the frequency of crashes.” Results from several studies and field testing show that maintaining adequate pavement friction is essential to prevent or reduce roadway vehicle crashes effectively. Transportation agencies use spot friction measurement devices, such as locked-wheel skid trailers, to measure pavement friction numbers in their existing safety and pavement management practices. However, the traditional spot friction measurement cannot safely and accurately collect friction data at curves or intersections, where the pavement polishes more quickly, and adequate friction is more likely to be absent. As noted by the FHWA, friction data for safety performance is best measured with continuous pavement friction measurement (CPFM) equipment. Florida Department of Transportation (FDOT) District 7 conducted a pilot study of CPFM in the Tampa Bay Area in 2023. This pilot includes a district-wide field data collection of CPFM on state roads using SCRIM (Sideway-force Coefficient Routine Investigation Machine), a full-scale testing equipment for pavement friction measurement in highway speeds without traffic control, for approximately 2,000 lane miles. This study uses the SCRIM data to develop a procedure to prioritize Resurfacing, Restoration, and Rehabilitation Projects (3R) projects. Safety performance functions (SPFs) and crash modification factors (CMFs) were developed to address the safety effects of pavement conditions (e.g., friction number, macrotexture, and roughness index) for various roadway facility types (urban/rural, segment/intersection/curves, and two-lane/multiple lanes). The Potential for Safety Improvement (PSI) was used to categorize roadway entities into different safety tiers. The roadway entities in the critical safety tier, which indicates the most opportunity for safety improvements, will be selected for the economic appraiser and prioritization analysis using the developed SPFs/CMFs. The developed procedure supports FDOT District 7’s decision-making on their 3R project selection and prioritization.