Oversupply of parking spaces in transit connected developments

Professor Robert Cervero of Berkeley, one of the world's leading transportation researchers, with his colleagues did a study on parking requirements for _suburban_ multiunit housing developments proximate to transit stations in the East Bay region of San Francisco and Metropolitan Portland. See Are TOD's Over-Parked? (summary) and the full report.

They found that more parking was required than used, as well as interesting findings about how demand for parking increases with the distance from the transit station. That may seem obvious (of course it is), but hopefully then the point should be understood that ideally more housing should be located more closely to the transit station, and that housing immediately located at the transit station shouldn't be required to provide large amounts of parking.

From the article:

Our research also showed that size and distance matter. In general, peak parking levels were highest for large-scale apartment projects with generous amounts of parking per unit and that were farthest from the nearest station. For every 1000 feet walking distance that a project lies from a station, we estimated, peak parking increased by 0.7 cars per dwelling unit. Case study work also showed that apartments served by retail shops, that enjoyed direct access to station platforms, and whose shortest walking path was not too circuitous tended to have lower peak parking levels.

Proximity, density, mixed use nature, and urban design all matter.