Warning devices for reducing speeds on curves

Roadway designers use various warning methods to aid drivers to navigate sharp horizontal curves due to intrinsic dangers. There is a suspicion however that these devices are often misinterpreted or disregarded by drivers and thus reducing their effectiveness and not achieving intended reduction in operating speeds. The objective of this study is to evaluate the use of several warning signs and pavement markings at sharp rural horizontal curves, and to evaluate their effectiveness in relation to speed reduction. A series of treatments were applied to three curves and speed data were collected over a two-day period at three locations approaching the curve over a distance of approximately 350 m. The results indicate that the most promising treatments in reducing operating speeds are flashing lights and transverse lines. An analysis of the over the 85^th percentile speeds showed also significant reductions indicating that there was a greater impact for the higher operating speeds: a fact which could be considered more important than the smaller overall reductions noted.