Low-cost measures for reducing speeds at curves on two-lane rural highways

This paper investigated, by means of a dynamic driving-simulator experiment, drivers' behavior at curves on rural two-lane highways in relation to different advance warning signs, perceptual measures, and delineation treatments. The tested treatments were intended to alert drivers to the presence of curves, prompting a reduction in curve approach speeds, and to affect drivers' speed as they drove through curves. A benefit-cost analysis was performed to determine the economic feasibility of applying the countermeasures to speeding tested in the driving simulator. Study results showed that all the treatments produced significant effects on drivers' speed behavior at curves on rural two-lane highways. The perceptual treatments (i.e., colored transverse strips, dragon-teeth markings, and colored median island) were the most effective. The safety benefits measured in lower crash costs arising from speed reductions were much greater than the costs of the alternatives. The most cost-effective treatment was the curve warning sign because of the lower cost. However, colored transverse strips and dragon-teeth markings produced higher benefits and were highly cost-effective for average daily traffic greater than 1,000 vehicles per day. The study results strongly support real-world implementation of colored transverse strips, dragon-teeth markings, and the colored median island.