Bus bunching refers to the phenomenon that several buses arrive at a station within a short time period. Bus bunching often occurs on urban bus routes. It greatly increases passengers’ waiting time and reduces quality of transit service. The primary of this study was to analyze the temporal-spatial features of bus bunching by conducting an in-depth analysis of empirical bus GPS trajectory data obtained in Nanjing, China. The GPS data were inputted into the ArcGIS to clearly track the bus trajectories on the spatial map. A data processing procedure was followed to estimate the arrival and departure time at each station. Then the spatiotemporal trajectory picture was drawn for the bus route where the bus bunching was clearly identified. The study also analyzed the headway features of consecutive buses at the different stations, and evaluated the variation of time headway which indicates the severity of bus bunching. The results showed that when the bus bunching firstly toke place, it persisted on downstream stations for a long time. The bunching severity will also increase at downstream stations which reduces the reliability of bus arrival. We also identified the scenarios that the bus bunching was caused by the overlong bus dwelling time at a station and the different travel time of buses.

CICTP