Green Transportation Act This bill incorporates greenhouse gas emission reduction in various transportation-related planning activities and programs. Specifically, states and metropolitan planning organizations must address greenhouse gas emission reductions and certain other issues (e.g., public health and climate change) in long-range and other planning related to highways and public transportation. The bill also makes reducing carbon dioxide and other greenhouse gas emissions from the transportation system a national goal of the Federal-aid Highway Program. The Department of Transportation (DOT) must establish applicable performance measures and standards related to that goal. Additionally, states and metropolitan planning organizations may use certain funding available through the National Highway Trust Fund to develop standardized models and methodologies to measure and monitor transportation-related greenhouse gas emissions. DOT must collect and organize such models and methodologies in a publicly available clearinghouse and report about them to Congress. Further, DOT must establish a program to fund projects that support the reduction of greenhouse gas emissions from the surface transportation system. As part of this program, DOT must annually evaluate carbon dioxide emissions on public roads and evaluate states' progress in reducing emissions.