There’s been a surge of interest in re-invigorating downtowns by returning to what made them interesting to begin with. Loosely collected under the rubric Smart Growth, initiatives like the New Urbanism and Complete Streets aim to create environments less dominated by the needs of automobiles and more focused on the multi-modal access that was common before suburban bedroom communities and shopping strips.

With this effort to better balance vehicles, pedestrian traffic, bicycles, and transit comes a complex set of questions about the role of cars and parking. Not that parking was ever easy. But as established central business districts compete with suburban malls and office parks that offer plentiful free parking, many communities aim high with minimum requirements and low with rates.

It’s a recipe for underutilized parking that can’t break even.

With many tenants demanding parking at high stall-per-square-foot ratios, providing ample parking is a challenge for public officials and private developers alike. Increasingly, however, they’re being pressured to offer less parking to encourage greener transportation modes and people-friendly streets. While laudable, this creates a whole new set of problems.

“We hate parking!” a transportation planner once gleefully announced as she recommended not accommodating any cars. Balance is crucial, but with so many competing considerations—urban design, economics, aesthetics, real estate markets, environmental concerns, and public perception—it’s hard to chart a course.

Parking requires careful consideration of the specific patterns and needs of the area in question. There are no rules of thumb.

Why formulas aren’t enough

The problem is that parking has grown up as, and continues to be, an offshoot of traffic engineering more than urban planning. Thus, plans often rely heavily on quantitative models that provide an incomplete picture.

Municipal planners typically take a civil engineering approach, assessing need by counting how many vehicle trips an area experiences each day. There are two problems with this:

  • It provides only immediate data and nothing about need five or 10 years out; and
  • It’s passive.

Rather than trying to figure out how many spaces will meet today’s needs, figure out how parking can be used to promote urban planning goals, promote business development, and enhance quality of life. While this certainly involves measurements, such an analysis focuses on how parking can influence behavior. Behavior, in turn, is influenced by pricing (how much to charge in different parts of the city), and how long people are permitted to park.

The Institute of Transportation Engineers’ landmark Parking Generation provides data on how much parking a given land use will generate. However, the data were collected for stand-alone land uses and mostly in low-transit areas. While its ratios help in understanding peak potential demand, they’re more of a starting point than an answer.

The Urban Land Institute’s Shared Parking manual accounts for mixed-use settings where the interaction between land uses that have different peaks (e.g., offices and cinemas) can reduce overall parking needs, and provides a method for modeling the reductions. This adds much-needed nuance to the planning of anticipated build-outs in mixed-use areas, and is a more valuable tool for downtown or other mixed-use environments.

But a central business district is too complex for simple quantitative modeling. Unlike traffic engineering, parking has a lot to do with consumer choice.

In September, parking authorities in 21 countries answered a survey on trends and challenges. When asked to name three cities with trendsetting approaches to parking, respondents most often cited:

  • London (named by nine countries)
  • San Francisco (seven)
  • Amsterdam and Paris (five each)
  • Barcelona, Seattle, and Tokyo (four each)
  • U.S. respondents also identified New York, Los Angeles, and Washington, D.C.

For example, when I meet with stakeholders I inevitably hear that parking is “totally full” and it’s “impossible” to find a space. Then I do occupancy counts and almost always find plenty of empty spaces, but just outside the core destination blocks. The shortage is actually a shortage of spaces right where people want them: in front of their destination. Given free or cheap parking, everyone will choose the best spaces and be frustrated that they’re “never” available.

Given rate stratification, however, consumers make different decisions. Some pay the premium to park near the front door; some walk a few blocks for free or cheap parking. (In towns that don’t have paid parking, time limits are used to stratify demand but this is generally less successful.)

So the answer to “Do we have a parking shortage?” and “How much parking do we need?” can’t be answered with a code calculation or statistics. How much you need depends on the radius you’re willing to consider and how much you’re willing to charge to make use of that radius.

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