Transportation networks are the most extensive public infrastructure across the Salish Sea landscape, and support all other human activities. Road are frequently constructed on eathworks called a road prism, used to level the landscape and allow high speed travel. As roads cross watersheds their earthworks capture and direct water, segment wetlands into cells, and cross floodplains and channels.
Notes on direct impacts
- USGS research has described PAH release from road sealants, with coal-tar sealants having 1000 times the release.
- Copper in brake pads can be found in highway runoff at levels that affect aquatic life.
Notes on indirect impacts
- Transportation networks can capture and accelerate delivery of storm runoff into streams and rivers.
- Transportation networks enable residential and urban development, which reduces forest cover, increase impervious surfaces and ultimately leads to degradation of aquatic ecosystems.
Notes on Transportation Network Management
- The Federal Highway Administration or FHWA passes federal funds through the Washington State Department of Transportation which in turn subsidizes Counties in their development of road-based transportation networks, including bridges and tunnels.
- The Federal Transit Administration or FTA provides a similar support for mass transit systems.