Numerous studies identify potential relationships between speed characteristics and roadway safety. More specifically, the risk of crash involvement may be positively correlated with speed variation and higher vehicle speeds are generally correlated with increased crash severity. Most previous studies rely on spot speed studies, using automated traffic counters or laser/radar guns at specific points on transportation facilities, assuming that spot speed measurements and laser speed profiles can be considered representative of roadway operating speeds. However, spot speed studies cannot capture the speed profile of each individual along the entire route or driver/vehicle characteristics that may contribute to crash frequency. This paper uses GPS-equipped vehicle data obtained from the Commute Atlanta instrumented vehicle program to measure operating speed characteristics on urban streets in Atlanta, GA. The authors examine the relationship between the 85th percentile of monitored speed variance and crash frequency on these facilities. It is found that for given facility types, namely collectors and local roads, speed variance may potentially be used as a safety surrogate in the development of a screening tool to quickly classify safety conditions on urban streets. (A). For the covering abstract of the conference see E216632.
Abstract