From safety point of view, railroad- highway grade crossings are critical points in rail transportation system and are sites with specific characteristics in the elements of road transportation systems such as bridges and tunnels. Although, accident frequency in crossings is low in comparison with the accident frequency in roads, studies demonstrate that it is still very high compared to the low number of crossings and relatively high standard of railway safety. Identification of high risky grade crossings is a basic method to reduce harmful accident impacts and optimize resource allocation and quick improvement. Employing statistical models is a solution for identifying black spot crossings which are developed, based on the relationships between accidents and geometric design, control devices and traffic attributes. Despite developing such models for other road spots such as bridges and road intersections, no frequency prediction model for railway- highway grade crossings in Iran has been generated so far. The present study tries to develop a frequency prediction model using geometric and traffic grade crossing characteristics and the occurred accidents in the years 2002 to 2006. Average daily vehicle traffic, average daily train traffic, availability of gates, crossing location (rural or urban), train speed and highway pavements are significant and are introduced in Poisson model. Considering the estimated coefficient for each factor and expected changes in future, a new outlook of safety situation of grade crossings can be imagined. Use of this method is suggested for prioritization of grade crossing securing, prediction of future crossing situation with change of characteristics, resource allocation, etc. in Iran railway system
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