Evaluation of Pavement Treatment Strategies for Friction-Deficient Horizontal Curves

In friction management of horizontal-curve pavements, highway agencies develop treatment strategies for friction-deficient pavements mainly based on past experience or industry recommended practices. In the absence of an engineering procedure to evaluate the effectiveness of friction treatments, there is no sound basis for comparing the effectiveness of different treatment strategies. To overcome this limitation, this study explored a mechanistic approach to analyze friction treatments for a horizontal curve and compare the magnitudes of skid resistance improvement, reductions of skidding potential, and terminal polished skid resistance. This was achieved by applying the finite element simulation technique to calculate the tire-pavement skid resistance available and the safe vehicle speeds under a given set of design operating conditions. For illustration, five friction treatments for pavement curves were analyzed: resurfacing/overlay, high-friction resurfacing, longitudinal grooving, transverse grooving, and resurfacing/overlay plus raising of superelevation. The skid resistance, safe vehicle speed, and terminal skid resistance were determined for different wet-weather operating conditions. The operating conditions were defined by horizontal-curve geometric parameters, pavement surface properties, wheel load, geometric and structural properties of tire, and water film thickness. The effectiveness of an improvement treatment is evaluated by skid resistance improvement, skidding potential reduction, and terminal polished skid resistance. Two quantitative indicators were introduced for effectiveness evaluation: safe skid resistance margin Delta SN and safe vehicle speed margin Delta V. The proposed approach presents a quantitative engineering assessment procedure for highway agencies in the selection of a suitable treatment, and maintenance planning in their friction management of horizontal-curve pavements.