A Greedy Path-Based Algorithm for Traffic Assignment

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A Greedy Path-Based Algorithm for Traffic Assignment

Xie, Jun / Nie, Yu (Marco) / Liu, Xiaobo

This paper presents a new path-based algorithm for the static user equilibrium traffic assignment problem. Path-based algorithms are generally considered less efficient than bush-based counterparts, such as Algorithm B, traffic assignment by paired alternative segments (TAPAS), and iTAPAS, an improved version of TAPAS, because explicitly storing and manipulating paths appears wasteful. However, our numerical experiments indicate that the proposed path-based algorithm can outperform TAPAS or iTAPAS by a wide margin. The proposed algorithm, sharing the same Gauss-Seidel decomposition scheme with existing path-based algorithms, delivered a surprising performance, most likely due to its two main features. First, it adopts a greedy method to solve the restricted subproblem defined on each origin–destination (O-D) pair. Second, instead of sequentially visiting every O-D pair in each iteration, it introduces an intelligent scheme to determine which O-D pairs need more or less work. The proposed algorithm is also more straightforward to implement than bush-based algorithms.