World Bank is applying to transport initiatives a new and distinctive method of greenhouse gas (GHG) analysis as part of its comprehensive GHG accounting policy. In transport, choices by travelers determine usage, and a fundamental trend in much of the world is strongly boosting GHG emissions: the massive rise in motorization as household incomes and technical advances make it affordable. This tendency will push transport fuel emissions much higher unless projects sharply expand the opportunities and incentives for users to adopt low-emission modes. The World Bank's GHG analysis for transport shows whether a given transport project can help lower the trajectory of the sector's GHG emissions. A central feature is an estimate of the wider social costs of emissions under various modes, for example, air pollution and accidents, as well as climate change. Including them greatly increases the demonstrated benefit of emissions reducing projects and thus will also help accelerate the move to a sustainable transport sector.