Examining The Impact Of Ramps On Lane Operating Features At Urban Expressway Bottleneck In Shanghai, China

For better refined management of urban expressway traffic, it is necessary to quantitatively analyze the impact of ramps on lane-operational capacity and lane flow distribution at the bottleneck of an urban expressway. Employing the survival analysis method and the maximum value method, this paper calculates the lane-operational capacity before and after the traffic flow breakdown. And then lane-operational capacity, lane flow distribution of the expressway section, and the relationship with the ramp position are analyzed. Through the analysis of actual data, several interesting conclusions are drawn: (1) the lane-operational capacity of the inner lane is higher than that of the outer lane on the two-lane section without ramp. The lane-operational capacity of the three-lane section without ramp is ranked as middle lane, inner lane, and outer lane; (2) on-ramp has little influence on the lane-operational capacity of the expressway section. The inner lane of the expressway section around the on-ramp has a larger operational capacity than outer lane, consistent with the section without a ramp. The lane-operational capacity of the expressway section around the on-ramp decreases slightly both on the inner lane and outer lane; (3) the off-ramp has considerable influence on the lane-operational capacity of the expressway section. There is a significant reduction in lane-operational capacity of the expressway section outer lane around the off-ramp. On the expressway section after the off-ramp, the lane-operational capacity of the outer lane is higher than that of the inner lane, which is opposite to the section without a ramp; and (4) ramps have significant impact on lane flow distribution. On the sections without ramp, the lane with the largest capacity bears more traffic flow, and lane flow distribution is shaped like a bracket. On the sections around the ramps, lane flow distribution is shaped like a scissor.