The document presents scenarios for transportation in Hanoi, Vietnam out to the year 2020 that illustrate the impacts of different policies on vehicle use, emissions, and urban development. Reasonable estimates for vehicle growth, travel distances, and emissions factors are used to model the effects of stronger pollution standards, improved fuel efficiency, and policies promoting public transit, walking, and biking. The scenarios show that acting now to shift toward more sustainable transportation options is important as Hanoi is already highly motorized and millions more residents are expected by 2020, so current decisions will largely determine the future shape and feel of the city.