Real estate developers will have to contribute financially to the transportation infrastructure necessary to create walkable downtown areas.

That's the message of University of Michigan professor, developer and author Christopher Leinberger, who says that contribution is the way developers will benefit from pent-up demand for housing in city centers instead of suburban sites.

Christopher Leinberger, a visiting fellow at the Brookings Institution and author of the book "The Option of Urbanism," told a conference of transportation planners and real estate officials Wednesday in Ann Arbor that development of new mass transit systems will spur demand for downtown living, similar to the way the interstate system spurred suburban development.

"If you're not investing in your transit systems, bicycle systems, walking systems, you're going to miss the major infrastructure investment in the 21st Century," he said. "If you don't put in integrated transportation systems, you're going to be relegated to the 20th Century."

Leinberger and Gail Achterman, chair of the Oregon Transportation Commission, spoke to a combined session of the University of Michigan/Urban Land Institute Forum and the annual Sustainable Mobility & Accessibility Research & Transformation meeting.

Achterman told of her experience in Oregon, which has strict land-use laws requiring large cities to have integrated transportation plans. But beyond those plans, she said, a commitment to actually building the infrastructure is needed.

"You need more than plans. You have to have investment, and particularly you have to have investment in new transportation infrastructure to make and create livable communities," she said.

"Transportation drives development," Leinberger added.

He drew a parallel between the type of rail systems needed to create vibrant downtowns to the rail systems that developers funded in Michigan 100 years ago to bring residents out to the suburban land they had just purchased. He said developers paid for 80 percent of those systems, but then abandoned them.

"We need to get back into this land use transportation convention. Developers are going to be called upon to share a portion of their future revenues to amortize the debt for transit systems," he said.

Leinberger also had a stark assessment of the current economic downturn and its implications for developers -- he described it as a shift from drivable suburban communities to downtown urbanism.

"We're seeing structural shift in what the market wants. This is not a cyclical downturn. We did not just overbuild a few products. We have built the wrong product in the wrong location. That's what caused this economic collapse," he said. "There's tremendous pent-up demand for the opposite of what we've been building for 60 years."

Freelance reporter Dan Meisler can be reached at danmeisler@gmail.com.