Matthew Roth is a writer and

No sizable city in the country, or likely the world, has been able to say with any certainty how many parking spaces it has, public or private, until now.

Over the last 18 months, the San Francisco Municipal Transportation Agency (MTA) has tallied every publicly accessible parking space within city limits, including free and metered spaces on-street and every publicly accessible garage [PDF map].

The total number of spaces, as Mayor Gavin Newsom recently announced on his Youtube site, is 441,541. Of the total, over 280,000 are on-street spaces, 25,000 of which are metered. For just the on-street spaces, that is roughly the equivalent area of Golden Gate Park.

“Most cities have very little knowledge of their parking inventory,” said Rachel Weinberger, a planning professor at the University of Pennsylvania and former transportation policy adviser to New York Mayor Michael Bloomberg. Weinberger called the parking census a “tremendous effort.”

“Without the basic knowledge [city planners] have no basis on which to make decisions about future supply policy, about current management policy or even about how their transportation systems are working.”

Don Shoup, planning professor at UCLA and author of the definitive book on the history of parking, The High Cost of Free Parking, was excited to hear the news. “San Francisco’s census of parking spaces is a great achievement, and the first of its kind anywhere,” he said.

The release of the public parking space census coincides with the redesign of the website for SFPark, an occupancy-based parking management trial funded with a $19.8 million federal congestion mitigation grant, which among many objectives, seeks to manage the supply of parking by adjusting the cost to match demand. To put that in laymen’s terms, if SFPark works well, there should be enough parking at the curb so that drivers don’t have to circle the block endlessly searching for that elusive space. By gradually adjusting the price of parking up or down in the pilot areas, the city expects to create roughly one or two free spaces per block face at any time, the original purpose of parking meters when they were introduced in the 1930s.

Jay Primus, who directs the SFPark trial for the MTA, said the parking census was the first step toward a better understanding of how parking works in San Francisco, filling a void where city planners could only make rough estimates previously. “If you can’t manage what you can’t count, doing a careful survey and documenting all publicly available parking was a critical first step for the MTA for how we manage parking more intelligently,” he said.

Primus explained that his team combed through copious records to determine total public garage spaces, including the MTA’s own facilities and city tax records for private facilities. For on-street unmetered spaces, he sent interns out across the city to count every fifth block, a 20 percent sample size. At every free opportunity, he sends out more interns and recently estimated they had increased their sample size to 35 percent. Time willing, he hoped to count every single space on every street.

Aside from satisfying his own penchant for good data, Primus said the data was essential if they expect the SFPark pilots to succeed in making parking more convenient for drivers and reducing traffic.


SFPark_Map_small.jpgClick image to enlarge. Map depicting SFPark trial areas. Courtesy:

In order to expand the impact of the data, the MTA has released it to third-party developers on its website, which the agency hopes will spur creative applications for smart phones much as software engineers have done with the MTA’s route and schedule information. With these applications, Primus expected to “see less circling for parking, less wasted fuel, and reduced greenhouse-gas emissions. It could help to save people both time and money,” he said.

“San Francisco is on the forefront of parking management,” said Mayor Newsom, who has championed open data through the DataSF website. “By combining this data with our innovative approach to local government open data, we continue to transform government to work better for all of us.”

Beyond the benefits to drivers and the savings from reduced congestion, the parking census data will inform the general discussion of parking supply and development, which can become highly contentious and emotional.

Jason Henderson, a San Francisco State University Geography Professor, said San Francisco Planning Commission hearings sometimes devolve into unhelpful arguments over the supply of parking without good data to back up either side’s assertions.

“It’s very important to have as fact-based a conversation as possible,” said Henderson.

The San Francisco Planning Department’s Joshua Switzky agreed with the importance of the data. “It’s the kind of information that always comes up during review of big projects, especially when parking is being debated,” he said. “Everyone — from neighborhood groups, to planning commissioners, to transit advocates — wants to know the general parking supply in an area.”

Now that the publicly accessible spaces have been counted, the MTA plans to move forward with a count of private garages. Some of those interviewed for this story imagined there could be as many as 800,000 spaces in total, or at least one parking space for every San Franciscan.

What the Census Reveals

Should San Francisco have a parking space for every person residing in the city? Should the city continue to mandate one new parking space for every residential unit built, the metric required in planning code in much of the city?

Using data from the MTA’s Transportation Fact Sheet, Weinberger noted that despite 28.5 percent of San Francisco households not owning cars, “enough households have multiple vehicles that the city’s population, collectively, owns over 8 percent more vehicles than households.”

“As we all know, the more parking there is available, the more convenient car use becomes relative to other travel options,” said Weinberger. “The more convenient car use is the more likely a car will be used.”

Shoup marveled at how much parking in San Francisco is free, especially when compared with the price of housing. “One surprising result is that 72 percent of all the publicly-available parking spaces in the city are free,” he said. “In San Francisco, housing is expensive for people but free for most cars.”

Todd Litman, the director of the Canadian think-tank Victoria Transport Policy Institute, said the census showed that “in many situations there is not actually a shortage of parking spaces, rather, the available spaces are not being well-utilized.” Litman said the solutions were parking management strategies such as more car sharing, efficient pricing, and parking cash out, which “can address parking problems in ways that also help achieve economic, social and environmental objectives.”

All the parking experts agreed that San Francisco was leading the way in the effort to better understand the relationship between parking policy and the context of the urban environment.

“Parking policy is a pretty powerful tool for shaping street use, urban fabric and mode choice,” said Weinberger. “The true power in this information rests on what the city decides to use it for.”