This is a nifty site

http://www.fhwa.dot.gov/environment/wildlifeprotection/index.cfm

If you're like me you cringe every time you drive past a dead animal by the side of the road. You might even feel guilty even if you've never once hit an animal because, let's face it, just having the roads disrupts territory and endangers wildlife.

The above site lists simple projects the Federal Highway Administration does to protect wildlife. I read about bunny houses that only cost twenty dollars and are made of brush and an effort to save mussels when a bridge was rebuilt. It's pretty interesting. Take a look.