Improved Random Walk Method Verified in a Large-Scale Urban Network for the Sampling of Alternatives in Route Choice Modeling

The first stage in route choice modeling is the generation of the route choice sets, which directly affects the accuracy of model estimation. The random walk method proposed by Frejinger et al. for this purpose has the advantage of directly calculating the probabilities of paths chosen. However, its application has seldom been seen in a large-scale network of a real large city in the literature. To fill this gap, the performance of the random walk algorithm is examined on a real network in Shanghai, China. It is found that it cannot avoid loops and frequently produces overlong alternative paths. By locating the root cause, an improved random walk algorithm is proposed in this paper. The idea of the new algorithm is to change the value of the shape parameters. Instead of a fixed value in Frejinger et al.'s method, the shape parameter in this approach is dynamically changing, controlled by the allowable probability difference and generalized minimum cost. The algorithm is validated in a large-scale network using real travel survey data. The results of the empirical analysis suggest that the proposed random walk algorithm has a significant improvement with respect to the number and length of generated alternative paths compared to those from the original algorithm. This study's primary contribution is to significantly improve the adaptability of the random walk method in large-scale road networks, which is crucial for improving the accuracy of route choice models and understanding of route choice behaviors.