Study was conducted on accident experience of traversable medians of various widths on limited access, high-speed highways. Data were obtained through the cooperation of state highway departments and turnpike authorities. To increase the number of samples, state highway departments were requested to select and submit data for sections of rural, divided, high speed highways having limited access characteristics with few intersections and little roadside development since operations of these roads were considered comparable with those of parkways and turnpikes. All pedestrian and intersection accidents were excluded from the accident data used. Factors which seem to affect accident rates are: (1) the overall standards of design, road user velocitation, (3its climatic environment, and (4) differential in vehicle speeds. In total accident rates and median accident rates there appears to be no correlation between the accident rates and width of median. A definite relationship was found between increased traffic density and head-on collisions. A California division of highways analysis of median accidents showed substantial reductions in head-on accident experience with increased width of median up to fifty feet. Studies were also made of different types of physical barriers now employed in the medians of high speed, rural roads. The superiority is demonstrated in this study of a traversable median, forty or more feet wide over any type of existing physical barrier employed to prevent head-on accidents on high speed, limited access facilities.
Samenvatting