Formulation and Solution for Level of Service Reliability with Variable Traffic Demand

A concept of level of service reliability (Los reliability) is proposed from the point of view of individual driver and system manager. By treating OD demands as discrete random variables, the most probable demand state space can be obtained via the search of an ordered tree. For any given state vector in the most probable state space, the link flow can be calculated based on the stochastic user equilibrium (SUE) traffic assignment method. The performance function of link and road network can be defined according to the ratio of link (network) flow to link (network) capacity. Then, an approximation algorithm is established to estimate Los reliability based on the pessimistic and optimistic hypotheses. Finally, some computations on a small road network are carried out in this paper. The numerical results show that the proposed algorithm can achieve better Los reliability estimated value with less expense.