Transportation
Increased vehicle traffic, roads and parking lots contribute pollutants to the air, land and water. They also fragment forests and reduce habitat available for wildlife.
As development continues to spread across the Bay watershed, people are living in outlying areas and traveling greater distances by car to reach work, school and shopping centers. In many urban and suburban areas, cars are the only way for people to get around, as sidewalks, bike lanes and public transportation are not available. This has not only caused increases in traffic congestion, but also in airborne pollution and polluted runoff.
How is transportation a pressure on the Bay?
Increased vehicle traffic and transportation infrastructure (roads and parking lots) contribute pollutants to the air, land and water. They also fragment forests and reduce habitat available for wildlife.
Air pollution/deposition
Cars, trucks and other on-road vehicles are a significant source of airborne nitrogen and chemical contaminants. Air pollution not only affects the quality of the air we breathe; it also impacts the land and the water.
- Pollutants released into the air are carried by winds and fall back to the earth's surface via rain, snow, fog or dry particles.
- Airborne pollutants that fall on the land can be transported by runoff or groundwater into streams and rivers to the Bay.
Vehicles are also a source of greenhouse gas emissions that contribute to global climate change.
Polluted runoff
Transportation and its infrastructure (roads, parking lots and driveways) account for 55 to 75 percent of all paving of open space in cities, towns and subdivisions. This conversion of natural land to impervious surfaces creates excess stormwater runoff, which contributes a growing amount of pollution to the Bay and its rivers and streams.
The impacts of runoff from roads and parking lots include:
- Alteration of natural water flow in local streams that drain into the Bay.
- Stream bank erosion, which causes increased sediment pollution and loss of habitat for aquatic creatures.
- Increased nutrient and chemical contaminant flows into storm drains and local waterways.
Habitat loss and fragmentation
Roads and other transportation infrastructure cut the land into smaller, more isolated fragments. Land fragmentation:
- Disrupts animal migration routes.
- Makes forests less resilient to major disturbances and more prone to negative influences like wildfires and invasive species.
- Reduces total available habitat and separates animal and plant populations.
- Energy Use and Environmental Protection: Fact sheets, reports and presentations on various environmental topics and transportation from the Surface Transportation Policy Partnership.
- Green Highways Partnership: Activities and efforts by the U.S. Environmental Protection Agency to establish a rating system for building and maintaining roads and highways.