Environmental sustainability or equity in welfare? Analysing passenger flows of a mass rapid transit system with heterogeneous demand

Comfort could be one of the major factors influencing demand for public transit systems across income groups. Those in the high-income group, typically car owners, value comfort more than those in the traditionally captive low-income group. This paper examines the heterogenous effect of crowding on mode choice and the subsequent demand for mass rapid transit (MRT) system across income groups using stated-preference data collected from Dhaka, Bangladesh. The crowding variable was incorporated into mixed logit models as a Bureau of Public Roads (BPR)-type function, establishing non-linear sensitivity of different income groups to the effect of crowding on mode choice. We then estimate equilibrium passenger flows for different income groups for multiple scenarios based on varying levels of fares and capacity under the stochastic user equilibrium (SUE) condition. The consumer surplus, revenue, and total surplus associated with each scenario were calculated. The findings show that fares that maximize social welfare are not equitable as they result in very low MRT demand among the low-income group. Meanwhile, higher fares result in greater demand for MRT among the high-income group, improved social welfare, and less total car use. These results highlight the trade-off between an equitable public transport system and environmental sustainability.