Insights from Spatiotemporal Analysis of Taxi Supply-Demand Imbalance in Bangkok

Abstract

Supply-demand imbalance is a critical problem in street-hail taxi systems. In a high-demand or overserved area, where pickups exceed drop-offs, taxis have to compete intensely for passengers. This results in a reduction of their revenues. On the other hand, in a low-demand or underserved area, where taxis are less likely to search for passengers, the passengers experience a longer waiting time. Moreover, taxis often perceive that finding passengers in a low-demand area is more difficult. This results in the refusal of service for trips to destinations in low-demand areas, which is one of the critical problems in the Bangkok taxi service. In this study, based on more than four million real taxi trips in Bangkok, we quantify the effects of the supply-demand imbalance on passenger search time and distance. In contrast to the conventional perception, we demonstrate that, on average, taxis in underserved areas do not have longer search times and distances than those in overserved areas. In fact, there is almost no correlation between the level of supply-demand imbalance and passenger search time and distance. These new insights change how recommendation and rebalancing models for traditional street-hail taxi services and future autonomous taxi services should be designed.