The Setting And Safety Evaluation Of The Variant Interchange

As an important part of expressway, the stand or fall of the interchange design directlyaffects the service level of expressway. There are relatively mature practice and experience forthe design of the plain terrain interchanges both at home and abroad, but for the mountainousinterchanges, the design mode is fixed and lack of flexibility.Through studying characteristics and the commonly used types of the mountainousinterchanges, this paper analyses and sums up the existing mountainous interchange types,analyses and studies the affecting factors for the mountainous interchange setting, putsforward the setting form of the flexible interchange ramp in mountainous area. The layout ofvariant interchange in mountainous area mainly include: trumpet interchange unbundling,changing directly right turn to ring right turn, changing ring type to semi-directional type andline development type interchange. This paper analyses the main affecting factors of theinterchange. The variant interchange ramp alignment, mainline and passageway arecomprehensively considered, the safety design of the variant interchange focusing on siteswith potential risks has been researched, and the flexibility design index of ramp andpassageway is put forward, to ensure the safety of the variant interchange.This paper will be divided into three parts to establish safety evaluation system of thevariant interchange: ramp safety evaluation, mainline safety evaluation, and passagewaysafety evaluation. The incidence of the possible accident would be greatly reduced by thesafety analysis and evaluation of each part of the variant interchange.Through research and analysis by practical examples, the safety performance of thevariant interchange is specifically argued, the alignment should be adjusted if safety risksexist. For project which has existed or no space to adjust, the safety improvement measuresshould be set up, to ensure the safety of driving of the vehicle.