Transportation supply and demand management strategy over time

Including both transportation supply and demand management (TS-DM) measures underpins the development of an effective transportation management strategy. One may consider transportation infrastructure provision as the supply; whereas the traveling public as the demand, subject to demand management measures which are often introduced as a separate policy tool, distinct from supply management. Nevertheless, synergy can be achieved in solving congestion problems when TS-DM strategies are developed jointly in an integrated manner. On the other hand, costs and effects of an integrated TS-DM strategy will accrue over a long period of time, subject to the ever-changing demand patterns, gradual network upgrades, varying road pricing and location costs. Therefore, it is important to include temporal dimension in our analysis. In this study, we aim at developing a theoretical framework which produces optimal TS-DM strategy over the planning horizon, typically, 10, 20, or even 30 years. In developing the TS-DM strategy to fulfill a certain objective, the problem can be formulated as a bi-level program, with the upper level specifying the objective to be optimized subject to demand growth and economic constraints, while the lower level contains the time-dependent user equilibrium models. This paper focuses on developing the bi-level formulation for determining the time-dependent TS-DM strategy. Some properties of the model are studied.