A transit path planning model based on the heterogeneous road network

Abstract

Optimal path planning is the critical technology for public transit system. In this paper, we propose a new transit path planning model-3-layers heterogeneous road network model (3-LHRN). Based on this model, we can generate optimal path results, making a good match with real life. Some approaches have been explored in the past to tackle the optimal path planning issues. Taking aim at the least transfers, the approaches are based on transit matrices of the map. However, the precondition of the algorithms is that transfer stops must be the same, and it is required that the origin and destination points must be the exact bus stops. These preconditions cause some inconveniences and inaccuracy. For instance, the final path results may have more than two transfers without acceptable walking distance. Besides, even though passengers know some marking buildings around the bus stops, without names of the particular stops, they cannot inquiry the optimal path. With respect to the model based on heterogeneous road network, we address the following two key technical issues: (1) setting up the heterogeneous road network with three layers: public transit layer, road layer and POI (Point of Interest) layer. The three layers form a unified entity by coordinates and attributions in order to provide enough information for the optimal path. They communicate with each other by exchanging spatial data and attribute data, (2) computing the optimal path according to the heterogeneous road network. We get appropriate bus routes from public transit layer, locate the desired positions close to some particular bus stops according to POI layer, and compute the walking distance between POI points and bus stops. At last, we generate the final optimal path from the information computed as above. The transit path planning model based on heterogeneous road network is applied to the public transit network of Beijing, China. It is demonstrated that 3-LHRN model can produce much more optimal paths with fewer transfers than ordinary models. Keywords-GIS; path planning model; transit network; least transfers; heterogeneous road networkI.