Effect of Midblock Access Points on Traffic Accidents on State Highways in New Jersey

The focus of this research was to conduct a statistical analysis of the effect of various traffic, geometric, and environmental factors on accident rates on New Jersey State highways. The main concern was the effect of midblock access points on accident rates. To identify the characteristics of access-related accidents (section accidents), a comparison study was conducted to investigate the effect of various factors on both section accidents and signalized intersection accidents. Access density was found to be a contributing factor to the occurrence of accidents, but it was not the only factor. About 30 percent of accidents on the study routes in New Jersey are expected to occur between signalized intersections, whereas 7 percent of the accidents are due to maneuvering to and from access points. Accident rates for sections between signalized intersections were better represented by a log-normal distribution than by a normal distribution. The effect of single factors such as access density, median, shoulder, number of lanes, and speed limits on accident rates was also investigated with the Kruskal—Wallis test. Of the above factors, only the number of lanes was found to be nonsignificant to accident rates. Two regression models for four lanes with shoulder, two lanes without shoulder, and four lanes with median were found to have sufficiently good R² values and their use is recommended with caution. Hourly and subhourly traffic flow data, average operating speed and variance data, and law enforcement data will further improve the analysis of accident data.