ANALYSIS OF TRAFFIC FLOW AT INTERSECTIONS NEAR RAMPS OF OVERHANGING FREEWAYS
高架路匝道附近的交叉口交通流分析

Traffic flow at the intersections near the ramps of overhanging freeways was analyzed in this paper. A modified 1-D pipe-flow model was established by introducing a relaxation term in the motion equation. Based on the model, a case study was conducted for the traffic flow at the crossing near the Wuning Road off-ramp of the Inner Ring Freeway in Shanghai City. Numerical simulation was performed with special attention to the disturbing effect of right-turning vehicles from the intersecting main road, the Wuning Road in this case. The obtained results agree quite well with observed data. The analysis shows that the "pin" effect of right-turning vehicles from the intersecting road is the principal cause of congested traffic at certain intersections, and the inappropriate design and construction of ramps in front of busy crossings enhances the congestion.