The purpose of this investigation was to attempt to determine quantitatively the optimum median opening spacing on multilane divided highways without access control when safety, level of service, and roadside access requirements were examined simultaneously. The effect of certain roadway characteristics on the accident rate and level of service for every section of multilane divided highway (without access control and with non-crossable medians) in north carolina were considered. Data were collected for 92 study sites, and accident records of over 6,000 accidents that occurred on these sites during a 21-month period in 1963 and 1964 were related by a distance measurement to a median opening and evaluated. Data were stratified by accident type and location type and were analysed by multiple regression techniques. Prediction equations were also developed to estimate the accident rate and level of service for specific locations on multilane highways. Findings of this investigation indicate that median openings, per se, are not necessarily accident prone under conditions of low volumes, wide medians, and light roadside development. However, as volumes increase and development increases commensurately, the frequency of median openings does have a significant effect on accident potential. (Author/publisher)
Abstract