This month’s blog post comes from Janice Kaspersen, editor of Stormwater magazine.

Did you drive to work this morning? Was a parking space waiting for you when you arrived? Many cities require developers to provide a minimum number of parking spaces for office, retail, and residential buildings; sometimes the number is based on the square footage of the building, sometimes on occupancy. Many calculate the required number of spaces based on peak demand. As this article from the Economist notes, some cities ask for what seems like an excessive amount. Cupertino, CA—home to Apple’s new headquarters building—requires two parking spaces per apartment, one space for every three seats in a fast-food restaurant, and seven spaces per lane in a bowling alley (plus more for employees). Apple’s headquarters will have 11,000 parking spaces for 14,000 workers, and the parking will take up more area than the offices and laboratories.

Another thing parking does, although the Economist article doesn’t mention it, is add impervious surface to the landscape. This article from Stormwater by Lisa Nisenson and Clark Anderson suggests that cities reviewing their ordinances and codes can and should eliminate excess parking: “Like street design, parking occupies a conspicuous spot on the impervious audit radar. Almost all code reviews recommend reducing the amount of parking in standards. However, there is no magic code change wand that reduces spaces without some pushback from retailers, landowners, and stakeholders concerned about spillover parking. We found that successful efforts often began with parking space utilization studies. These studies look at the degree of over- and undersupply, how to handle peak parking events, and management options within a ‘parking-shed.’ Parking studies usually initiate a broader effort to ‘find’ parking spaces on existing paved areas. Even so, there are a couple of quick fixes. For example, basing parking requirements on staffed space rather than gross square footage can reflect demand while reducing spaces needed.”

The Economist article notes that after London got rid of parking minimums altogether in 2004, essentially letting market forces decide how much would be available, the number of spaces in residential areas actually dropped. In general, eliminating excess parking is a good thing, not only in terms of managing stormwater but in making a city more livable: “The more spread out and car-oriented a city… the less appealing walking and cycling become,” the article points out. “Parking influences the way cities look, and how people travel around them, more powerfully than almost anything else.”

Cities with minimum parking requirements also make things tough for redevelopment and infill projects, which often don’t have enough land available to satisfy them. Going underground is not an attractive option, either: “Creating the minimum number of spaces adds 67% to the cost of a new shopping center in Los Angeles if the car park is above ground and 93% if it is underground.” And everyone—even those who rely on public transportation—subsidizes that parking by paying more for restaurant meals, theater tickets, and retail goods.

It’s a fine line, though—what happens when there’s not enough parking? Drivers spend time and gasoline—and get frustrated and angry—driving around searching for an empty space. By one estimate, cars in Los Angeles’ Westwood area, which has very few spaces, drive an additional 950,000 miles per year just in the quest for parking spots.

What are the parking requirements in your city? Do you see a trend toward reducing or increasing parking spaces? Encouraging greater use of public transportation or carpooling?