A Seven-Year Field Evaluation of Friction Performance, Durability, and Safety of High-Friction Surface Treatments across Multiple Field Sites

High-friction surface treatment (HFST) is widely used to improve roadway safety, particularly at high-risk curves under wet conditions. However, most prior studies are limited to short-term evaluations and often examine friction, durability, and safety separately. This paper is the first of its kind to provide a comprehensive evaluation of HFST performance based on field observations and measurements across 25 sites over the anticipated seven-year service period. Four primary early-age distresses were identified: reflective cracking, aggregate loss, delamination, and surface wrinkling, with reflective cracking being the most prevalent. Distress occurrence and durability were influenced by substrate conditions, construction temperature, and surface pretreatment methods. Kaplan–Meier analysis showed that approximately 64% of sites remained in service after seven years, with most failures occurring within the first five years. HFST exhibited high initial friction numbers (FNs) of 80-100, followed by a gradual decline and stabilization at roughly 60-70 after five years. Surface texture showed a similar trend, with mean profile depth (MPD) decreasing from about 1.9 mm to around 1.0 mm while retaining sufficient macrotexture to sustain friction performance. Notable variability across sites highlights the influence of traffic, environmental conditions, and construction practices. Safety analysis using a negative binomial model and the empirical Bayes (EB) method indicates substantial crash reductions. A representative crash modification factor (CMF) of 0.40 is recommended, corresponding to an approximate 60% reduction in total crashes.