An investigation of Bus Rapid Transit System (BRT) based on economic and air pollution analysis (Tehran, Iran)

Traffic congestion, along with its harmful impacts on public health, the economy, and the environment, is a major urban problem in metropolises. Due to a growing urban population and private vehicle ownership, heavy traffic has become intolerable for Tehran's residents, particularly during peak hours. Bus Rapid Transit (BRT), which is a high-quality bus-based transit system that delivers high-speed and efficient services, is among the solutions to such traffic issues. This paper investigates the first line of Tehran's BRT with the aim of enhancing the efficiency of the system. Aimsun has been employed to simulate implementing exclusive bus lanes, decreasing bus headways, implementing actuated traffic signal and revises the bus stations in 10 different scenarios. Finally, nonlinear regression models were employed to predict reductions in commute times, fuel consumption and pollutant emissions. Results show that by converting shared lines to exclusive lines, commute times could reduce by 2.95%, CO emissions by 9%, PM emissions by 1.13%, NOx emissions by 3.45%, and fuel consumption by 5.3% per kilometer. In addition, by replacing fixed signals with actuated signalization along the route, commute times were reduced by 6.31%, CO emissions by 25.9%, PM emissions by 3.42%, NOx emissions by 6.2%, and fuel consumption by 5.26%. Considering the nature of the proposed scenarios, their impact on vehicle performance assessed and according to the environmental and economic analysis of the scenarios were justified. For the economic analysis of the scenarios, their costs and benefits were used to calculate the payback period. The scenario of full exclusive bus route (i.e. scenario 4) with 73 days had the longest and the station modification scenarios (i.e. 8 and 9) had the shortest payback period after the station modifications.