artists involved in urban design projects

I'm doing some research into artists involvement in urban design projects. I would be interested to learn about any practices that employ artists to work on projects from the initial stages of design.

 If anyone is interested in this there was recently a good article by Tarek Merlin, an architect at SMC Alsop, who has recently appointed a lead artist on a mixed-use residential scheme http://www.building.co.uk/story.asp?sectioncode=31&storycode=3086020&c=0

I know of a few artists working in this way, but they do seem thin on the ground. I am also aware of the PROJECT initiative run by Public Arts South West, CABE and Arts & Business, but would be really interested to hear about any other projects that have involved artists in the design process.

many thanks

Tom