| Summary: | 碩士 === 逢甲大學 === 交通工程與管理所 === 90 === The need for a methodology to provide time-dependent estimates of traffic flows and associated performance measures in networks arises in several problem areas, including Advanced Traffic Management systems (ATMS) and Advanced Traveler Information systems (ATIS). In order to properly capture dynamic, real-time flow distribution in an information-based network, the concept of dynamic traffic assignment has been proposed to extend traffic assignment techniques in a dynamic aspect.
Four different approaches, including mathematical formulations, optimal control theory, variational inequalities, and simulation-based approach, have been applied in developing Dynamic Traffic Assignment (DTA). Two assignment principles, namely, system optimization (SO) and user equilibrium (UE), have been widely accepted and used in transportation planning. The UE rule implies that at equilibrium no motorist can experience a lower travel time by unilaterally changing routes; the SO rule implies that the system overall travel time is minimum.
Within the micro-simulation based DTA procedure, an iterative scheme is developed to generate time-dependent least marginal cost path based on the simulation model, DYNASMART. The core of the procedure is DYNASMART, a simulation-assignment model, and the model allows consideration of individual trip maker decisions at the origin as well as at each node along the way to the destination, in addition to describing the dynamics of vehicular traffic flow.
In the procedure, link marginal costs are estimated and utilized within a time-dependent least marginal shortest-path algorithm. Thus, the estimation of link marginal cost is an important factor for micro-simulation based DTA. Different estimation approaches, such as dynamic link performance functions, queue-based delay estimation, and numerical estimation, have been developed for estimating link marginal cost. This research aims at exploring marginal cost calculations and optimizing the estimation in the micro-simulation based DTA procedure.
Numerical experiments on a test network are conducted to investigate the accuracy of link marginal cost. Relationship between time-dependent marginal travel time and path travel time are compared to obtain further understanding of marginal cost calculation characteristics of those approaches.
One new model is constructed based on the results of numerical experiments on the test network. Numerical experiments on an actual network are also conducted to investigate the accuracy and efficiency of the micro-simulation based DTA procedure using new marginal cost estimation model.
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