Safety impact of edge lines on rural two-lane highways in Texas

The purpose of this paper was to analyze the safety impact of edge lines on rural two-lane highways in Texas. The research found that edge-line treatments on rural two-lane roadways may reduce crash frequency up to 32 percent and the highest safety impacts occurred on curved segments of roadways with traffic lane widths of 9 to 10 feet. In addition, edge-line presence shows some positive safety impact in reducing speeding-related crashes during darkness that may indicate better driver path and speed perception. Crash statistics comparisons were made for Texas rural two-lane highways with and without edge lines. In addition to general crash frequency analysis, varying traffic lane and shoulder widths, roadway curvature, and factors such as crash type, intersection presence, light condition, surface condition, crash-supporting factors, severity, driver age, and driver gender were considered for all the crashes over a four year period. Pavement markings are an important part of the traffic control system, especially on rural two-lane roadways where these treatments often are the major traffic control measure. Compared to other types of longitudinal markings, the effect of edge lines on safety and driver behavior has been much less investigated.