The purpose of this study is to determine the safety impact of raised curb medians, two-way left-turn lane (TWLT) medians, and undivided cross sections on vehicular and pedestrian traffic. This study concentrates on medians located on unlimited access arterials in central business districts (CBD's) and suburban environments. A total of 32,894 vehicle and 1,012 pedestrian accidents were analyzed from 145.9 mi (234.8 km) of unlimited access arterials located in three large metropolitan areas. Operational data in the form of vehicle-pedestrian conflicts, pedestrian walking speed, and pedestrian use of medians for refuge were obtained and analyzed as part of the study. The accident data were used to develop nonlinear predictive models for estimating the effect of cross-section type on vehicular and pedestrian accidents. Raised median pedestrian accident rates are significantly less than pedestrian accident rates on undivided arterials in suburban areas, and less than both TWLT and undivided arterial pedestrian accident rates in CBD areas. No significant differences were identified between the pedestrian accident rates of raised curb and TWLT medians in suburban areas. The CBD vehicle accident rates of raised medians, for both midblock and signalized intersections, are higher than that of TWLT medians and undivided cross sections. A greater percentage of raised median vehicle accidents, however, are of lower severity (property damage only) than that of TWLT and undivided cross sections for both CBD and subaurban locations. (Author/publisher)
Abstract