Widening Roads: Short-term Traffic Relief, Long-term Emissions Increase

Report from Sightline concerning transport strategies in North America

'Building new additional highway lanes increases total global warming emissions over the long term - even if the project reduces congestion and emissions over the short term. Sightline's analysis of highway-widening projects and road emissions has implications for transportation proposals such as the Columbia River Crossing between Oregon and Washington, and the Gateway Project in greater Vancouver, BC.

Report Summary:

• Adding lanes to a highway will increase total global warming emissions over the long term - even if it reduces congestion over the short term.
  
• Specifically - we estimate that each extra lane-mile built will increase emissions of carbon-dioxide, the main greenhouse gas, by more than 100,000 tons over 50 years.
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  Any short-term fuel savings from congestion relief are quickly overwhelmed by increased traffic volumes on the roadway. '