By Rori Gallagher.

Even in these difficult economic times, California's population continues to grow, and those additional people are going to need a place to live. Recent legislation in California directs city planners to make environmentally responsible choices for new housing. One way to do that is to create transit villages.

The idea is to design housing near a transit station with easy access to retail and commercial space. That way people can drive less if they want to. Some transit villages are easy to identify as pre-planned developments, like the transit village in South San Francisco. Others developed more organically, like the area surrounding the Rockridge Station in Oakland.

As with all new development and redevelopment, there's always a concern about gentrification. Most cities have a requirement that a certain percentage of new units are offered below market rate. But some longtime residents of established communities, like San Mateo, worry about new development changing the character of the community. In order to make transit villages work, designers have to carefully blend new development with the existing community, creating a truly pedestrian-oriented destination. Check out a map of transit-oriented development in California. Also, here are some fun audio walking tours of transit-oriented development projects in the Bay Area.

Listen to the Mass Transit Housing Plan radio report online.

Credit: California High Speed Rail Authority

One of those outstanding questions is: Where will the train go?

In the Bay Area, that has been a huge issue. There are two proposed routes (check out an interactive map here) — one through the East Bay and the Altamont Corridor toward Sacramento, and the "preferred alternative," which runs down the Peninsula, through San Jose, Gilroy and the Pacheco Pass, and then loops back around to Sacramento.

Some rail advocates filed a lawsuit, pushing the state to do more study, particularly environmental study. The Pacheco Pass route cuts through some pristine landscape, and that worries environmentalists. And the Altamont route runs through some of the heaviest traffic corridors in the Bay Area, so a high speed train could relieve some of the East Bay's congestion. In addition, the Peninsula communities of Menlo Park and Atherton joined the lawsuit, because they're concerned about the potential of massive above-the-street construction there.

The Rail Authority says it's working with communities to answer their concerns. For instance, it's possible that some of the high speed rail stations could go below ground on the Peninsula — and that they hope to build BOTH routes eventually. Right now, they say, the Pacheco Pass route is preferred, but they point out that it's a long way till the tracks go down and the train starts running, and there will be a lot to work out over the next decade.

Listen to the Fast Trains radio report online.

Image source: Michael Patrick

Andrea Kissack is Senior Editor for QUEST at KQED Public Radio.