New research finds that parking minimums are indeed bad, but that parking maximums still need fine-tuning.
In 2004, London reformed its parking policy to encourage alternative transportation modes. The city replaced its minimum parking standard, which required developers to create a certain number of parking spaces and has been found to increase driving, with a cap on spaces. The hope was that this new parking maximum would "promote sustainable transport choices" and "tackle congestion."
A policy shift is a great chance to study urban behavior in real-time. As we showed last week, in the case of red-light cameras, such a scenario is catnip to researchers who want to study empirically — as opposed to consider theoretically — a potential city lifestyle change. The outcomes of London's 2004 reform could influence how other major cities (such as New York) handle parking regulations of their own.
In an upcoming issue of Urban Studies, researchers Zhan Guo and Shuai Ren of the Rudin Centre for Transport Policy and Management at NYU consider two core questions when it comes to London's reform. First, does the parking minimum truly create more parking than people want? Second, is a parking maximum necessary to promote sustainable transport, or will the market alone take care of it?
On the first question, Guo and Ren returned a pretty definitive yes. They examined parking supply at 216 residential developments in London approved from 1997 to 2000, when the parking minimum was in effect, and then roughly 8,250 developments approved from 2004 to 2010, after the minimum was removed and the maximum imposed. Before parking reform, developers created 94 percent of the required minimum; after it, they created just 52 percent of the old minimum.
In other words, parking reform reduced the parking supply roughly 42 percent, the researchers report. Additionally, about two-thirds of developers provided a supply below the old minimum — further evidence that the minimum encouraged the construction of excessive parking spaces. Guo and Ren conclude that 98 percent of the reduced parking supply came from removing the parking minimum:
It is clear that, with the minimum standard but no maximum, most developments do not provide more than the minimum required. With the maximum standard but no minimum, most developments provide less than the maximum allowed.
Onto question number two: the effectiveness of the new maximums. Since the purpose of London's parking reform was to promote alternative transportation, the researchers looked at how parking supply fluctuated in areas with high density and transit access after 2004. What they found is that that the actual parking supplied was higher in Central London, where density and access are greatest, compared to adjacent outer areas.
Guo and Ren call this finding "unexpected." They suspect that local authorities may want to keep a high maximum (and therefore allow more spaces) to avoid a parking spillover onto already crowded streets in Central London. Another explanation is that the market simply wants more spaces there: people who can afford to live downtown are willing to pay a premium for parking.
In any event, the researchers found that, at least in central cities, the markets don't always regulate parking supply exactly the way they should. Central London's "deregulated parking market appears to provide more parking in the densest and transit-richest areas, and does not take into account the high social cost of driving and the opportunity cost of transit." They conclude that London's parking maximum is still too high in places:
In summary, the London parking reform provided solid evidence to understand two parking policies under heated debate: the minimum and maximum standards. The elimination of the minimum standard was highly effective in removing excessive parking, but still not enough to form an efficient parking market.
That conclusion isn't going to satisfy everyone. The evidence here overwhelmingly suggests that parking minimums do distort the supply of spaces, but exactly what ceiling to replace them with remains open to interpretation. The un- (or, at least, less-) regulated market in London does seem to give people the parking they want. Whether it gives London what the city wants — namely, increased transit and decreased congestion in the places that need it most — is a different question.