Safety evaluation process for two-lane rural roads: A 10-year review

A practical procedure was developed that explicitly considers the driving behavioral and safety rules of a horizontal alignment for the evaluation of roadway new designs; redesigns; and projects of rehabilitation, restoration, and resurfacing. Design classes were developed to classify, from a traffic safety point of view, roadway sections as good, fair, or poor; these design classes are associated with three safety criteria to develop an overall quantitative safety evaluation procedure for two-lane rural roads. The safety criteria are introduced to analyze and evaluate by (a) Safety Criterion (SC) I: the difference between design speed and actual driving behavior as expressed by variations in observed 85th percentile speed; (b) SC II: the difference between observed 85th percentile speeds on successive design elements; and (c) SC III: the difference between side-friction assumed and side-friction demanded at the 85th percentile speed level on curves. Furthermore, the issues discussed include design speed,...