Bilevel Highway Route Optimization

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Bilevel Highway Route Optimization

Kang, Min Wook / Yang, Ning / Schonfeld, Paul / Jha, Manoj

A new bilevel highway route optimization model finds highway alternatives that best improve the existing roadway system while optimizing the alternatives' alignments on the basis of geometric, cost, and operational considerations. The upper level of the bilevel structure represents a decision-making process of system designers in which possible highway alternatives are generated and evaluated. The lower level represents highway users' route choice behavior and evaluates how traffic in an existing road network is redistributed by the new highways. Various highway agency and user-related costs (such as earthwork, right-of-way, and travel time costs) are included in the model's objective function and used as key evaluation criteria. The model is tested with an example to check its capabilities and use in real-world applications. The results show that the model can optimize solutions within a reasonable computation time and that locations of the new highways are sensitive to redistributed traffic in the modified road network as well as to unit costs and other inputs. It is expected that highway planners and designers can greatly benefit from the proposed model, which offers optimized candidate alternatives identified by comprehensive bilevel optimization procedures rather than merely satisfactory alternatives obtained from the trial-and-error process of the traditional approach.