A Partial-Fréchet-Distance-Based Framework for Bus Route Identification

The integrity of bus route information is fundamental to the analysis of operating status and travel pattern of urban public transport system. However, due to the malfunction of bus positioning devices or delayed update of database, the route information stored in positioning devices might be lost or erroneous. To address this issue, this paper designs a framework matching the bus trajectory with a set of predefined bus routes. The trajectories are first partitioned into segments using the spatio-temporal DBSCAN. Then, the curve similarity between trajectories and bus routes is calculated based on the metric of partial Fréchet distance, which searches for a best mapping between curves that minimizes the maximum distance between vertex pairs. A directed-acyclic-graph-based method is also proposed to compute the partial Fréchet distance. Finally, the best match for each trajectory is given based on the relative ranking. The proposed framework is evaluated on the bus trajectory data of Fuyang and Shenzhen in China. The experimental results demonstrate that the framework can well identify the underlying routes according to the recorded bus trajectories and suggest which route information needs updating.