关键词: 交通工程, 最优控制信号, 双层规划, 过饱和交通流控制, 通行能力限制, 出口匝道控制

Abstract:

During the rush hours, due to the limited traffic capacity, the oversaturated traffic flow at the downstream of off-ramp often propagates traffic queue to spillover back to the mainline of freeway leading to more serious congestion. To prevent this problem in this paper, setting the control signals at the off-ramp and the connected surface intersections, a bi-level programming (BLP) model is proposed to optimize the control signal timings in this area. The lower level of BLP optimizes the signal times of each independent intersections as the basic control plan. The upper level of BLP is aimed at optimal control strategy for all intersections of the area with considering the capacity constraint of the surface roads. Finally, choosing the Urumqi East Race freeway off-ramp as an example, the optimized results of the BLP model are verified and analyzed combined with Vissim simulation. The results indicate that, for the problems raised in this paper, the signal plan optimized by the proposed BLP model can effectively prevent the off-ramp queuing spill over which is leading mainline congestion. It can be more significant improving the system performance than the conventional nonlinear model, which is an improvement to the conventional optimization method.

Key words: traffic engineering, optimal signal timings, bi-level programming, oversaturated traffic flow control, capacity constraint, off-ramp control