There's a thread going on in City Discussions about urban parks, and a few people brought up capped freeways in their city.
http://forum.skyscraperpage.com/show...=180839&page=3
Take a look at this:
This is a roof that is planned to be built atop the San Francisco TransBay Terminal. It would replace the ugly concrete roof with a green one, basically creating a rooftop park in the middle of downtown.
Before:
http://www.sfgate.com/cgi-bin/articl...MNGS1D2189.DTL
After: And as you can see with the messy freeway covered up, it could open up more development next to the freeway.
http://www.sfgate.com/cgi-bin/articl...MNGS1D2189.DTL
http://www.sfgate.com/cgi-bin/articl...MNGS1D2189.DTL
Further reading on the one in San Francisco.
http://www.sfgate.com/cgi-bin/articl...MNGS1D2189.DTL
This is Woodall Rogers Park in Dallas.
http://www.renderosity.com/ballistic...ed-i-cms-14034
http://bennewelldallas.blogspot.com/...good-idea.html
http://untantonio.wordpress.com/2009...district-news/
Imagine having something like that in Austin on I-35 next to downtown.