A fast method for estimating railway passenger flow

To improve the situation for crowded commuters in Japan, it is important to plan a train schedule that considers passenger behavior, such as their choice of trains and the transfer stations used to reach their destinations. However, it is difficult to directly measure such detailed behavior using the present infrastructures, with which we can only get OD (Origin-Destination) data from the automatic ticket gates. The obtained OD data only consists of the number of passengers for each origin-destination and the time each passenger passes through the gates. In this article, to contribute to the planning phase of a new train schedule, the authors propose a method for estimating railway passenger flow using OD data. This paper firstly points out that the problems of estimating passenger flow can be boiled down to a shortest path problem of graph theory by assuming a certain passenger behavior model. By representing train operations in a graph structure, we can assume that a passenger will use the minimum cost path to his/her destination. This paper secondly proposes a method for conducting fast searches of the graph structure. The method uses the fact that railways operate on a time schedule. This method can estimate passenger flow fast enough so as to apply it to a practical train schedule planning support system. Lastly, the authors show the results of applying the passenger flow estimation system to a railway in an urban area in Japan.