Safety Evaluation Of Highway Interchange

Since the late 1990s, our country's transport construction especially the construction of high-grade highways has come to an unprecedented period under the influence of macro-policy. By the end of 2008, the total length of highways in operation had surpassed 60,000km, ranking second worldwide again. The development of transport construction will necessarily promote further perfection of theoretical knowledge,such as planning, designing, construction and supervision. Aslo, it will require even higher levels of highway safety design.Furthermore, with the constant development of highway construction, the construction conditions of interchange are becoming more complicated. Not only the space of interchanges become samller and smaller, and the types become more and more, but aslo the constraints of ramp alignment become more and more. Interchanges have been danger-areas of highway.In order to solve safety design puzzles which were brought by the changes of interchange construction conditions, the paper made a study of safety evaluation mainly in the following three aspects:In the addressing phase of highway interchange, it summed up theory and method of safety evaluation by studying the relationship between space of highway interchange and interchange safety, discriminating weaving segments of interchange and analyzing interchange's capacity.In the selection phase of highway interchange, by studying different types of typical interchanges and their safety features, analyzing the influences on interchange's safety that includes structure of interchange's entrances and exits, length of acceleration and deceleration lane, capacity of entrances and exits, it summed up interchange's type selection theory which meets the needs of interchange safety , and it put forward the safety design plan of entrances and exits of interchange.In the alignment design phase, by considering determination of interchange's specific parallel line index, vertical line index and transverse line index, it figured out the capable operational speed of interchanges on different ramps, and analyzed its coordination with design speed, thereby evaluated its safety.By generalizing all phases of interchange's safety evaluation, the paper put forward safety evaluation guide to conduct the safety design of interchange.