| Summary |
Kai-Lin Chang, 2007,06
Institute of Traffic and Transportation National Chiao Tung University
This study proposes two bi-level programming models -- operational model and planning model to achieve the goals for sustainable transportation along an intercity corridor. In the operational model, the upper level is to determine the optimal fare (toll) rates, while the lower level is to determine the optimal operating frequencies of transport carriers and patronage of passengers. In the planning model, the upper level is to simultaneously determine the optimal construction horizons and fare rates of transport systems, while the lower level is the same as that of the operational model. The underlying theories are basing on various objectives viewed by the government, transport carriers and passengers, which cannot be incorporated into a single-level programming model. The goal of government is to achieve sustainable transportation in terms of safety, energy consumption, air pollution, and travel time. The goal for transport carriers is to maximize their profits in determining the operating frequencies. The goal for passengers (road users) is to choose transport modes to maximize their utilities. It is assumed that Stackelberg equilibrium exists between the government (leader) and the transport carriers (followers); Nash equilibrium exists among the transport carriers in the lower level while competing the quantity (frequencies); and Stackelberg equilibrium also exists between transport carriers (leaders) and passengers (followers). Due to the complexity of the proposed bi-level programming models, this study develops a solution algorithm based on genetic algorithms (GAs).
To investigate the operationability of the proposed models and solution algorithm, this study tests an exemplified case of intercity corridor with four modes including air, rail, bus and private vehicles. Assume that the annual travel demand and its growth rate are given, the travel times of air and rail are constant, and the travel times of buses and private vehicles follow a BPR function. Under the demand of 50,000 trips per day, the results of operational model show that the optimal regulated fares (tolls) are NT$ 794, 1,508, 794, and 3,000, respectively, for rail, air, bus and private vehicle in association with the corresponding market shares 33%, 23.09%, 32.97% and 10.94%. If only a freeway system exists in this corridor at the beginnig, the results of planning model show that the three transportation systems should be introduced on the horizon of first year (railway), fourth year (airports) and seventh year (another railway). |
