Traditionally local zoning ordinances required project sponsors to provide 100% of the parking demand generated by the proposed project. More recently both Smart Growth and sustainability advocates have begun to question that approach as reinforcing the existing car culture. It is becoming more common, particularly in metropolitan ares with extensive public transit systems, to reduce minimum parking ratios thereby reflecting increased usage of public transit. In some cases, municipalities are going a step further and instead adopting parking maximums (i.e., rather than require a developer to provide a certain number of spaces, the city prohibits the developer from providing more than a certain number of spaces).
The underlying theory is simple enough to understand. Fewer parking spaces will eventually translate into fewer cars, less traffic, less land devoted to parking lots and parking garages and greater ridership on bus and rail systems. In turn, this means a reduction in exhaust emissions and gasoline usage and cleaner air. This trend is occurring in locales as disparate as New York, Seattle, Tacoma, Los Angeles and Fairfax County (VA).
When this new approach is put into practice, however, it can lead to some unexpected arguments being made by the parties who participate in specific project zoning decisions. For example, developers typically tried to reduce parking requirements to save money on construction and operation. Now developers may be arguing for permission to exceed the new parking maximums if they are afraid they will not be providing as much parking as prospective tenants are seeking. Neighborhood activists usually want to make sure that office workers and shoppers are not using up the scarce supply of on-street parking used by residents. With parking minimums, these activists usually were on the opposite side of the fence from developers. But with parking maximums, neighbors and developers can find themselves as allies fighting together against planning officials who seek to minimize the amount of new parking.
A recent cleverly designed study done in New York City made a compelling case that the availability of a guaranteed private parking space increased the likelihood of the car owner driving into Manhattan. This study of how parking minimums influence commuting patterns by Rachel Weinberger of the University of Pennsylvania has provided empirical support for parking maximum proponents who believe that restricting such parking will reduce commuter trips.