In the last 15 years, American cities have spent $100 billion on new rail transit projects. Proponents now justify the expense with claims that rail will reduce greenhouse gas emissions, but these projects fail to meet their promised reductions, a new Cato Institute study reports.

In "Does Rail Transit Save Energy or Reduce Greenhouse Emissions?" Cato senior fellow Randal O'Toole demonstrates that rail transit is ineffective at reducing carbon dioxide emissions.

"While most rail transit uses less energy than buses, rail transit does not operate in a vacuum: transit agencies supplement it with extensive feeder bus operations," O'Toole writes. "Those feeder buses tend to have low ridership, so they have high energy costs and greenhouse gas emissions per passenger mile. The result is that, when new transit lines open, the system as a whole can end up consuming more energy, per passenger mile, than it did before."

"Only a handful of rail systems are more environmentally friendly than a Toyota Prius, and most use more energy per passenger mile than the average automobile," O'Toole notes. He suggests that technological solutions to emissions are more promising and more cost-effective than expensive rail projects. Using biodiesel fuel, for example, "costs less than 10 cents per pound of CO2 saved, making it more than 25 times as cost-effective at reducing greenhouse gas emissions as light rail."

O'Toole recommends that instead of pursuing costly rail projects, cities should look at proven alternatives. These include powering buses with alternative fuels, increasing the concentration of buses on heavily used routes, building new roads, implementing tolls, coordinating traffic signals, and encouraging drivers to purchases more fuel-efficient cars.

"There may be places in the world where rail transit works," O'Toole concludes. "There may be reasons to build it somewhere in the United States. But saving energy and reducing greenhouse emissions are not among those reasons."