Study of the Capacity of a Road Network Basing on the Level of Service

This paper presents a bi-level programming for solving the capacity of a road network which considering both the link capacity constraints and the level of service. Conventional researches of the capacity of the road network mainly consider the link capacity constraint, but never take account of the origin-destination (O-D) travel time which the travelers sufficiently concerned. We construct a bi-level programming model, which considering both the link capacity constrains and the level of service for the road network when we calculated the maximum demand which the network can satisfy. In this paper, we adopt the external penalty function approach to solve the programming in order to avoid the initial solution is not within the scope of the feasible domain when we using the internal penalty function process. Finally, this model is applied to a simple network to verify the different level of service the travelers require, and the different maximum loading capacity the road network have. This shows that the transportation planning should not only consider the actual allocation of road infrastructure standards, but also consider the impact of the actual demand level. Only the supplies could satisfy the actual traffic demands, and then its significance is outstanding.