A Survey of Vehicle Separation Distances in Stopped Traffic

A common low speed motor vehicle collision scenario occurs in heavy traffic situations between two or more vehicles which were stopped in traffic prior to the collision. While information regarding the pre-collision spacing of the involved vehicles can be very useful to an accident reconstructionist, witness perceptions and statements regarding the distance between the stopped vehicles, prior to the collision, can be inaccurate. Physical evidence regarding precollision spacing is also unavailable in most cases. A study was conducted of several selected intersections in three major metropolitan areas in the United States of America. Publicly available aerial photography, rectified and scaled, was used to perform a statistical analysis of the distance between stopped passenger vehicles at busy traffic signalized intersections. This study can provide a basis for an informed assumption of the distance between stopped vehicles in stopped traffic when more reliable information is unavailable. The overall 5^th, 50^th, and 95^th percentile separation distances between stopped vehicles at the selected signalized intersections were determined to be 4.1 feet, 8.9 feet, and 20.9 feet (+/- 1 foot) respectively. The methodology of this study can also serve as a framework for future individualized research regarding more specific locations and scenarios.