Safety Analysis of Driveway Characteristics Along Major Urban Arterial Corridors in South Carolina

In April, 2013, the South Carolina Department of Transportation (SCDOT) initiated research to improve driveway safety and enhance access management practices in South Carolina. The intent of the study was to determine the potential safety and operational consequences of individual driveways and their specific characteristics, so that informed decisions can be made when granting or denying a particular access point permit application. The researchers examined current and historical practices used by other transportation agencies with regard to access management. A comprehensive driveway database was developed using empirical data collected along several corridors that was used to rank driveway related crashes from highest to lowest frequency. The researchers used this database to statistically analyze and identify the correlation of access issues with crash data from 2012. Crash data were associated with driveways using complex Geographic Information System (GIS) modeling tools. A new South Carolina Collision and Ticket Tracking System (SCCATTS) has enhanced crash location data significantly, and was found to be a critical component for correctly associating crashes with driveways. The statistical analysis identified several significant independent variables that influence crash rates either positively or negatively. The results indicate that increasing the distance between driveways, increasing the number of entry lanes, and having a raised median will decrease driveway related crashes. Conversely, increasing driveway width, corridor volume and corridor speed limit will increase crashes. Similarly, a driveway with high turnover land use, a driveway with full access (as opposed to right-in right-out), and the presence of nearby signalized intersections will increase frequency of crashes. The statistical analysis was used to develop crash modification factors for different driveway characteristics.