Managing conflicts between the environment and mobility : the case of road-based transportation and air quality in Mexico City

Abstract

In the planning of transportation projects, there may be tradeoffs between providing mobility and achieving environmental objectives. Managing such potential conflicts is important to ensure that the economic benefits of efficient and effective transportation services are realized while the social and environmental externalities, such as air pollution, are minimized. This thesis focuses on the case of the Mexico City Metropolitan Area (MCMA), arguably one of the largest and most polluted cities in the world. Air quality in the MCMA is of particular concern and motor vehicles are by far the largest contributors to emissions. The majority of all passenger trips. in the region are served by road-based public transportation, particularly privately-operated microbuses and vans known as colectivos. Colectivos have been identified as a major contributor to congestion due to their competitive nature and self-regulated operating practices, and a contributor to air pollution in the region as well. In general, public transportation is a highly visible sector that is subject to public scrutiny and regulation, and central to mitigating the negative impacts of increasing demand for mobility. In order to test the latter and explore the tradeoffs between mobility and emissions, a corridor model was developed. The results of the model show that giving priority to public transportation modes with dedicated rights-of-way and investing in new, larger vehicles may be effective strategies for reducing emissions and improving mobility for transit users. However, the net effect on total corridor mobility and emissions depends on numerous corridor parameters such as the level of congestion and the modal split. Strategies were also explored to strengthen the implementation and sustainability of public transportation regulations towards the dual objective of enhancing mobility while decreasing emissions. By integrating public transportation modes, networks, and institutions, it is believed that improvements can be achieved in both mobility and transportation-related emissions in the MCMA.