Study on Road Network Bi-level Programming under the Traffic Flow Guidance

A network design problem is formulated as a bi-level program generally. In the traffic system, on the one hand, guidance facilities are invested and built. On the other hand, travelers can choose their paths according to both guidance information and their experience. In this paper, based on the relationship above, the optimization plan is established. The objective function at the upper level is defined as the total travel time on the network, plus total investment costs of guidance facilities. The lower level problem is formulated as a stochastic user equilibrium model. General genetic algorithm (GA) is used to find the optimal solution. Rough set help GA work faster. Attributes reduction of rough set is adopted to filtrate new chromosome comes from crossover operation of GA. The result of a road network example verified high efficient of this combined method.