Proponents of compact development argue that rebuilding American urban areas to higher densities is vital for reducing greenhouse gas emissions. Compact city policies call for reducing driving by housing a higher percentage of people in multi-family and mixed-use developments, reducing the average lot sizes of single-family homes, redesigning streets and neighborhoods to be more pedestrian friendly, concentrating jobs in selected areas, and spending more on mass transit and less on highways.
Sometime in 2010 or 2011, Congress expects to decide how to spend the $250 billion or more of federal gas taxes and other highway user fees that will be collected over the next six years. The process of doing so is called surface transportation reauthorization. A major point of contention in this law is how much of our transportation system should be centrally planned and how much should be built and operated in response to the needs of actual transportation users.
Far from protecting the environment, most rail transit lines use more energy per passenger mile, and many generate more greenhouse gases, than the average passenger automobile. Rail transit provides no guarantee that a city will save energy or meet greenhouse gas targets.
Federal law requires metropolitan planning organizations in urban areas of more than 50,000 people to write long-range (20- to 30- year) metropolitan transportation plans and to revise or update those plans every 4 to 5 years. A review of plans for more than 75 of the nation's largest metropolitan areas reveals that virtually all of them fail to follow standard planning methods. As a result, taxpayers and travelers have little assurance that the plans make effective use of available resources to reduce congestion, maximize mobility, and provide safe transportation facilities.
In the face of high energy prices and concerns about global warming, environmentalists and planners offer high-speed rail as an environmentally friendly alternative to driving and air travel. California, Florida, the Midwest, and other parts of the country are actively considering specific high-speed rail plans.
Rising gas prices and concerns about greenhouse gases have stimulated calls to build more rail transit lines in urban areas, increase subsidies to Amtrak, and construct a large-scale intercity high-speed rail system. These megaprojects will cost hundreds of billions of dollars, but they won't save energy or significantly reduce greenhouse gas emissions.