See the Ultra pod system featured in this new video for the Urban Mobility segment of Current TV:

"Personal Rapid Transit systems, or PRT's like those found in London's Heathrow airport, offer an energy saving form of personal transportation. Consisting of electric, lightweight, fully automated vehicles, the PRT system runs on demand to pick up passengers at one stop and drive them directly to their destination, eliminating intermittent stops like that of buses and trains." (http://current.com/specials/urban-mobility/93432758_personal-rapid-transit.htm)