Field Evaluation of In-Lane Pavement Markings in Advance of Freeway Interchanges

Abstract

Freeway interchanges with lane drops, double-lane exits with optional lanes, and other unusual geometries violate driver expectations and may result in late lane changes and erratic movements near the exit gore. In-lane pavement markings can reiterate the information provided on overhead signs that depict the geometry of the upcoming interchange. Researchers at the Texas Transportation Institute designed and conducted field studies at freeway interchanges to evaluate the operational impacts of route shield and directional arrow in-lane pavement markings. The addition of route shields resulted in better utilization of optional and inside exit-only lanes. In addition, motorists made lane changes farther upstream of the exit and made fewer unnecessary lane changes after the installation of the route shields. The addition of directional arrows also positively affected the lane distributions and lane change rate, but the effect on unnecessary lane changes was not as evident. Researchers concluded that the installation of in-lane pavement markings (either route shields or directional arrows) improved operations and, potentially, safety at the interchanges studied. There is evidence to suggest that a combination of route shields and directional arrows may be more beneficial to motorists than directional arrows alone.