There are no readily available highway design standards aimed atproviding adequate ground clearance at rail-highway grade crossingsthat have humplike profiles. As a result, low-clearance vehicles--such as low-bed equipment trailers, automobile transporters, and car-and truck-trailer combinations--can become lodged or hung up at a crossing. A number of accidents of this type have been reported in recent years, but a literature search indicated that there is very little quantitative data on the magnitude of the problem. Traffic countdata from west virginia indicate that low-clearance vehicles make up about 2% of the traffic stream. Such vehicles are highly variable in their physical dimensions: ground clearances as low as 2 in. For a variety of wheelbases have been reported. A literature review is presented summarizing approaches to this problem that have been taken. These include specifying crossing physical characteristics and developing advance warning signs. In response to an identified need, the researchers developed microcomputer software that incorporates graphics and animation capabilities to simulate the movement of trucks over grade crossings and to predict where hang-ups will occur for a given crossing geometry. The software is described and its use demonstrated in a sample application. This paper appears in transportation research record no. 1327, Visibility, rail-highway grade crossings, and highway improvement evaluation 1991
Abstract