Crash Severity Modeling in Urban Highways Using Backward Regression Method

Identifying and classifying intersections according to severity is very important problem for implementation of safety related counter measures and effective models are needed to compare and assess the severity. Highway safety organizations have considered intersection safety among their priorities. In spite of significant advances in highways safety, the large numbers of crashes with high severities still occur in the highways. Investigation of influential factors on crashes enables engineers to carry out calculations in order to reduce crash severity. In the previous studies, there are no perfect models which are capable to illustrate the influence of human factors, road, vehicle, weather conditions and traffic features including traffic volume and flow speed on the crash severity. Therefore, this paper is aimed to develop the models for illustration of the simultaneous influence of these variables on the crash severity in urban highways. The models represented in this study have been developed using binary Logit Models. SPSS software has been used to calibrate the models. It must be mentioned that backward regression method in SPSS was used to identify the significant variables in the model. Consider to obtained results it can be concluded that the main factor in increasing of crash severity in urban highways are driver age, movement with reverse gear, technical defect of the vehicle, vehicle collision with motorcycle and bicycle, bridge, frontal impact collisions, frontal-lateral collisions and multi-vehicle crashes in urban highways which always increase the crash severity in urban highways. Obtained results show the effectiveness and capability of the developed models.

Development laws of geological hazards along urban highway in Southwest China and countermeasures for prevention and control

China is a mountainous country with highly developed road geologic hazards, which pose a great threat to theconstruction and operation of highways, bridges, and tunnels and to the safety of people and property. This paperdiscussed the types, basic features, formation, and prevention conditions of road geologic hazards in China basedon field research and study data collected thus far. The study considered an urban area of a city in southwestChina as the center and a geological field investigation was performed over a total of 282 km on three importantlifeline projects. The results show: Types of geologic hazards along the highways are mainly avalanches, debrisflows, and landslides, respectively. Among them, the landslips are mainly distributed along the roads, with slip,dumping, and wrong break types as the main ones;the debris flows are widely distributed, mainly concentrated inthe river valleys;and the unstable slopes are relatively few in number. Geological disasters are characterized bylarge-scale and concentrated triggering in time and space, and a single disaster can easily trigger other disasters,thus forming a chain of disasters. Neotectonic movement, seismic activity, topography, climatic conditions,stratigraphic lithology, and human activities are important factors leading to geologic hazards in the study area.This study is of great practical significance for reducing the occurrence of roadbed diseases and prolonging theservice life of highways.