Does Crowding Have a More Complicated Effect on Public Transport Users with Respect to Perceived Travel Time?

The issue of crowding in public transportation has long been of concern. Numerous studies have been conducted to address this issue. It has become increasingly common to convert crowding to something more tangible, such as cost and time, in recent years. As a result of converting crowding into time, the concept of perceived travel time (PTT) has been introduced. Viewing crowding from the perspective of PTT may provide new insights into crowding and its effects. Therefore, in this study the PTT was calculated using the data obtained from both automated fare collection and automated vehicle location systems for the most heavily populated bus rapid transit (BRT) line in Tehran, the capital of Iran. A total of 429,000 PTTs were calculated, and then cluster analysis was used to determine that crowding has a significant effect on the PTT, not only for those who travel during peak hours, but also for those who travel during non-peak hours. Crowding therefore appears to have a more complex effect that persists over time. We conducted a time series analysis for some selected origin stops to test this theory. For stops intersected by other BRT lines or metro lines, the results suggest that the difference between PTT and nominal travel time for each block (stop-to-stop distance) increases over time, despite the start travel time not being chosen during peak hours for these stops. Based on the findings of our study, crowding could even affect travelers traveling during low-demand hours if viewed from the point of view of PTT. This effect is referred to as the “dynamic effect of crowding” in this paper.