FAQ - Frequently Asked Questions from Caltrans’ Department of Environmental Analysis:
Research/Data Points- Research studies and reports from Caltrans’ Stormwater Program:
http://www.dot.ca.gov/hq/env/stormwater/special/newsetup/index.htm and http://www.dot.ca.gov/hq/env/stormwater/ongoing/index.htm
Commercial Transportation - Environmental Considerations from Caltrans for Commercial Vehicles:
http://www.dot.ca.gov/hq/tpp/offices/ogm/environment.html
Review the research: