Speed Reduction Techniques for Rural High-to-Low Speed Transitions. National Cooperative Highway Research Program. A Synthesis of Highway Practice

摘要

North America's rural landscape is dotted with isolated settlements, villages, and small towns that are typically located on rural roads where the general speed limit is 55 to 60 mph (90 to 100 km/h). Motorists are expected to slow down as they pass through these settlement areas, reducing their operating speed to 30 or 40 mph (50 or 65 km/h) in sections of road known as transition zones. In designating and designing transition zones, the ultimate goal is for motorists to reduce their speed in the transition zone to the point where they reach the lower speed limit at the start of the settled area. However, several factors thwart the goal of using transition zones to reduce driver speeds in settlement areas, including speed adaptation (the tendency for motorists to underestimate their travel speeds after having driven at a higher speed for a prolonged period) and the generally abrupt change from the rural road to the town or village streetscape. As a result, state departments of transportation (DOTs) and other agencies are interested in developing more effective speed reduction techniques for transition zones.