Integrating Skid Resistance and Safety Benefits into Life Cycle Cost Analysis for Pavement Surface Treatment Selection

Abstract

Even though 30% of the annual highway fatalities originate from inferior roadway conditions, crash costs under regular operations have seldomly been included in the life cycle cost analysis (LCCA). Among the various condition indicators, pavement roughness has been the most investigated on roadway safety, while skid resistance has been less studied. This paper presented an integral decision-making process to integrate pavement skid resistance and its corresponding safety benefits into the LCCA for pavement surface treatment selection. Built on the processing of an extensive amount of traffic crash, pavement skid, and surface condition data provided by the Oklahoma DOT (ODOT), friction demands at the investigation and intervention levels were recommended to trigger surface treatments. Later, friction deterioration models were established to evaluate the skid performance of treatments over time. Multivariate analysis results indicated that aggregate properties and treatment types were among the most important factors for pavement friction. Subsequently, an enhanced safety performance function (SPF) was developed to predict expected roadway crashes under different skid levels. Pavement friction was a statistically significant factor and had a negative effect on vehicle crashes. The predicted pavement friction variations and the corresponding safety benefits of surface treatments were calculated and included in a spreadsheet tool developed from this study. A case study was provided to demonstrate the LCCA results with and without considering the safety costs of different treatments. Neglecting crash costs in LCCA would result in agencies adopting alternatives with lower short-term agency costs but underestimating the long-term safety benefits.