An optical speed zone consists of multiple speed bars, each representing a uniform transverse marking pattern, spaced variably to convey to road users a sensory perception of increased speed while their vehicle travels ator near constant speed through the zone. This targets an instinctive driver reaction of relaxing the accelerator, causing the vehicle to reduce speed at the downstream end of the zone. This article describes the results of an installation of an optical speed zone in Mohave County, Arizona. The optical speed zone was installed on a two-lane rural highway tangent section. An evaluation of the zone showed a statistically significant reduction in mean speed downstream of the zone, with the greatest effect observed during nighttime hours. These findings indicate that an optical speed zone can be an effective, inexpensive low-tech tool for speed management.
Abstract