Ramp Design Model for Elevated Road Network in Corridor

Regarding the ramp design problem in the elevated road network,the ramp location always affects the network performance and whether there exists a design paradox.This paper investigates the ramp design problem by optimizing the ramp location and its capacity simultaneously.The ramp design paradox in urban elevated road network and its intrinsic reason are also discussed.A ramp design model is proposed as the bi-level programming considering the importance of ramp location for the elevated road network in a corridor.The design variables in the bi-level programming are ramp location,ramp capacity and ramp type.The design objective in upper level is to minimize the total travel cost in the network,and the traffic assignment in low level is user equilibrium problem.In the last section,numerical examples are conducted to demonstrate the merits of the proposed model.Meanwhile,some numerical results show that the proposed model guarantees promising effects.