Traffic Safety Analysis On Urban Underpass Tunnels

There is one kind of highway tunnels is named as urban underpass tunnels, which is loc ated in the city and constructed underground. Recently, there is more and more urban underp ass tunnels have been constructed due to increasing of urban transportation demand which br ings with continuous expansion and development of the city. Although the construction of ur ban underpass tunnels produce positive effects on reduction of urban roads land use, shorten traveling time and ease urban traffic. Currently, there is an upward trend to urban underpass t unnels traffic accident. On account of urban underpass tunnels is relatively isolated and situa ted in the city center, It is hard to dispose the traffic accident happen to such tunnels, result i n secondary accidents, as well as pollutes the city center. Given this, it is necessary and urge nt to analysis traffic safety specifically on urban underpass tunnels.In view of there is just a few existing literature on urban underpass tunnels traffic accid ents statistics and safety research. This paper firstly deals with characteristics and traffic acci dent features comparison between urban underpass tunnels and general roadways. Based on which, the time distribution, spatial distribution, crash characteristics and types of vehicle in accidents are studied through data analysis on national typical urban tunnels traffic accidents and urban underpass tunnel traffic accidents of Chengdu city. Then we obtain the hierarchy chart for influence factors of urban underpass tunnels traffic accidents. After that, the princip al component analysis function of SPSS software is employed to identify the traffic black-sp ots of individual urban underpass tunnel and multiple urban underpass tunnels, respectively. Furthermore, we improve the dominant influence factors distinguish approach according to p rincipal component analytical method properties. The empirically investigation is conducted, subsequently, on134cases of urban underpass tunnels traffic accident in Chengdu city of2011. Lastly, we raise some measures for traffic safety based on previous research result of this paper.