The 486 accidents reported by police to have occurred at railway level crossings in new south wales in the four years 1966 to 1969 were studied. Less than half were collisions between a motor vehicle and a rail vehicle. The remainder were mostly collisions between motor vehicles and fixed objects such as the crossing gates, fences, signposts, and so on. The distribution of reported motor vehicle speeds in the latter group approximated the normal distribution. However the reported speeds of motor vehicles that collided with rail vehicles followed the negative exponential distribution , implying that exposure time at the crossing has an influence on the incidence of accidents. Consequently there is a possibility that a legal requirement that a vehicle stop at a crossing it is otherwise free to cross may increase rather than decrease its risk of collision by prolonging the time it will spend in the conflict area. At some crossings sight distances, the approach speeds of trains and the performance limits of motor vehicles will so combine that automatic train-actuated warning devices will be the only reliable protection against collision. Surveys of motor vehicle speeds at crossings, having a variety of environmental conditions and methods for controlling road traffic, showed that a crossing open to motor vehicles has little influence on the speed of them, and that the drivers traversed the crossings at speeds which were not significantly different from their speeds on adjacent road sections with similar geometry and other characteristics. The distribution of vehicle speeds traversing crossings approximated the normal distribution. The spatial distribution of both groups of accidents (motor vehicle/rail vehicle collisions and motor vehicle/fixed object collisions ) over the 2,790 level crossings in new south wales followed a poisson (random) distribution. (Author/publisher)
Abstract