Air Quality


Air quality and global climate change are issues of growing importance to communities across the United States. Greenhouse gases generated by transportation have been identified as a major contributor to global climate change. In 2005, the Research and Technology Innovation Administration at the U.S. Department of Transportation reported that highway vehicle miles traveled (VMT) accounted for 81% of the total U.S. transportation energy consumption. VMT is expected to increase 60% from 2,952 billion miles traveled in 2005 to 4,733 billion miles traveled in 2030. During that period, U.S. carbon dioxide emissions are expected to increase by 35%. In an effort to combat the effects of greenhouse gas emissions, particularly carbon dioxide, and to meet emissions regulations embedded in clean air legislation, many communities are promoting the reduction of VMT. As gas prices rise, more people are turning to public transportation and bicycles while trying to reduce time spent behind the wheel. Efforts to reduce VMT are proving somewhat successful in the metroscape. In 1992 the average VMT for both Portland and the U.S. was 20.2. Portland’s VMT has held fairly steady since then. In 2005 the VMT was 20.3; by 2006 the number had dropped to just 20. Nationally, efforts have been less successful. Since 1992 the national VMT has been steadily increasing; in 2005 it was 23.8.

vehicle miles traveled
Sources: ODOT; US DOT