Identifying the Multimodal Hierarchy of Public Transit Systems Using Itinerary Data

Abstract

As urban mobility integrates traditional and emerging modes, public transit systems are becoming increasingly complex. Some modes complement each other, while others compete, influencing users' multimodal itineraries. To provide a clear, high-level understanding of these interactions, we introduce the concept of a macroscopic multimodal hierarchy. In this framework, trips follow an "ascending-descending" order, starting and ending with lower hierarchical modes (e.g., walking) that offer high accessibility, while utilizing higher modes (e.g., subways) for greater efficiency. We propose a methodology to identify the multimodal hierarchy of a city using multimodal smart card itinerary data and demonstrate its application with actual data collected from Seoul and the surrounding metropolitan area in South Korea.