The choices developing countries make today in building and expanding transport networks will irreversibly shape development for the next century. That is why urgent steps are needed to ensure that transport development avoids locking in carbon intensive or high-risk patterns. While investments in urban planning and public transportation pay off over the long term, they also entail high up-front costs, making it essential to scale up support from the World Bank Group and other international institutions. The commitment to achieving zero net emissions by 2100 made at the Paris climate negotiations cannot be achieved without radical changes in how cities grow, and transport planning must be part of green growth strategies. Furthermore, climate-related issues such as food security, extreme weather events, and the health impacts of urban pollution have ties to the quality, affordability, and availability of affordable transport in both rural and urban areas. With many cities in developing countries only now planning transport infrastructure, this is the ideal time to ensure that transport planning incorporates climate-smart and low-carbon priorities.