Comparative Study of Emissions from Bus Rapid Transit and Conventional Bus Systems

Abstract

Bus rapid transit (BRT) systems play an increasingly important role in urban transit systems throughout the world because they provide fast and reliable public transportation. BRT systems are designed to reduce harmful emissions, which are usually significant for diesel engines in conventional bus transit systems. However, a quantitative comparison of emissions is needed to verify whether reductions have been achieved. This paper compares the characteristics of the emissions of diesel transit vehicles from BRT and a conventional bus system to provide support for policy decisions on public transit management in Beijing. A vehicle-specific power-based emissions estimation approach was implemented with a heavy-duty transit vehicle that ran on diesel fuel to analyze the characteristics of the emissions of a BRT diesel vehicle and a conventional diesel bus on the Fifth Ring Road of Beijing. The emissions characteristics were compared from a spatial perspective (i.e., scenarios involving non–bus lanes, bus lanes, and an area near a stop or a station). The BRT system was shown to play a significant role in reducing emissions, compared with those from a conventional diesel bus, with 25.62% to 27.37% reductions in emissions mass per kilometer of oxides of nitrogen, hydrocarbons, carbon monoxide, and particulate matter under the non–bus lane scenario, 12.76% to 14.01% reductions under the bus lane scenario, and 22.94% to 37.25% reductions under the scenario near a stop or station. These results have important policy implications for development of strategies for public transit systems in Beijing.