The Simulation Analysis of Ramp Traffic Operation Characteristics on Double-Layer Compound Expressway

In order to alleviate the shortage of land resources in urban areas, the double-layer compound expressway was proposed. The composition and running speed of the double-layer expressway are significantly different from that of the urban viaduct. However, due to the lack of relevant engineering practice, a simulation test was carried out with the use of the VISSIM platform. First, one ramp forms were proposed on the basis of this expressway section: left into right, then used the orthogonal experiment method to simulate the different traffic environments; Secondly, the test result was analyzed from the aspects of efficiency, stability, and safety with surrogate safety assessment model (SSAM); then got the comprehensive evaluation index with the entropy method. The result indicated that the ramp is suitable for situations where the mainline has a small volume and a low flow direction, in addition, the ramp can adapt to higher design speeds.