Behind the scenes at the U40 Summit: See the $5,000 U40 Vision competition in progress [slideshow]

Autodesk Fellow Tom Wujec kicked off day two of Building Design+Construction's Under 40 Leadership Summit in San Francisco with a single challenge to the 65 participants: develop innovative solutions for today's pressing social, economic, technical, and cultural problems related to the built environment. 

Dubbed the U40 Vision competition, the program will award $5,000 in prizes to the teams that present the most compelling concepts. Thirteen teams are battling for the $3,000 grand prize and four $500 secondary prizes. 

The winners will be announced tonight. 

Here's a behind-the-scenes look at the action: