Abstract:Delhi is a rapidly expanding megacity. Population and vehicle use continue to expand, and vehicles are the principal source of severe air pollution. Yet vehicle ownership is still a fraction of that in industrialized countries. The complexities of Delhi's transport sector are examined, along with what kind of a future is likely and how it might be altered. Indian transportation experts and political leaders were interviewed, historical data analyzed, and various policy options and strategies reviewed. Because of large institutional, political, economic, and technological uncertainties as well as limited knowledge of travel behavior and preferences, two scenarios were created to characterize what is likely and what is possible. The "business-as-usual" scenario extrapolates from present trends in Delhi, modified to reflect existing policies and commitments. It results in dramatic increases in vehicle use, translating to about a fourfold increase in transport-related greenhouse gas (GHG) emissions between 2000 and 2020. The second scenario is premised on strong political and institutional leadership to enhance the economic, social, and environmental performance of Delhi's transportation system in which car use decreases and transit and bicycle use increase. Even with this aggressive shift toward more environmentally benign transportation, GHG emissions more than double during the 20-year period. Under any plausible scenario, GHG emissions will soar, but the lower GHG path leads to far fewer emissions and much lower transport and energy costs.