Issue 506 July 25, 2005
Issue 506 July 25, 2005
The second in our serial look at Donald Shoup’s recent opus, The High Cost of Free Parking. Zoning codes dictate the number of parking spaces required for each type of land use. According to the American Planning Association, cities set parking requirements for at least 662 different land uses – everything from “adult entertainment” establishments to nunneries (e.g. 1 space per patron, plus 1 space per employee on the largest working shift for adult entertainment and 1 space per 10 nuns for the nunnery). Shoup says the requirements are often simply pulled out of thin air. There are two primary sources for these requirements: the parking requirements of neighboring communities and the Institute of Transportation Engineers’ (ITE) Parking Generation manual. Both sources are problematic, but the second is all the more troubling in its faults because it purports to be scientific. Parking Generation recommends the exact number of parking spaces needed per square foot for dozens of different land uses, and supports those figures with scatter plots and studies. But Shoup shows that the recommendations are in fact derived from far too few studies to be reliable. Half of the parking generation rates are based on four or fewer studies and 22 percent are based on a single study. But even if an adequate number of studies had been analyzed, the rates would still be skewed high because nearly all of the studies examine the demand for free parking during times of peak demand in suburban locations with few, if any, alternatives to driving. Shoup compares this to the demand for free pizza. The slices go a lot more quickly if they are free than if they are sold at an appropriate price. Shoup says “city planners sometimes mistake Pandora’s box for a toolkit.” With the best of intentions, planners have “cured” parking shortages with a tonic that has made matters worse. The practice of setting off-street parking requirements in city zoning codes has become fully entrenched. Even for low-income housing projects where a majority of residents can’t afford a private vehicle, zoning codes require vast parking lots to meet a demand that will never materialize. Those lots not only add to the cost of a development, they also require that land which could otherwise be used for housing (or landscaping, etc). Overall, parking requirements increase the cost and diminish the supply of housing, and this effect is not limited just to low-income developments. A San Francisco study found that requirements for off-street parking increased housing prices by an average of $47,000 and increased the household income necessary to purchase a house from $67,000 annually to $76,000. Shoup calculates that parking requirements impose a public subsidy for drivers that came to at least $127 billion in 2002 (total annual land, capital and operating costs of U.S. off-street parking) and may be closer to $374 billion. For comparison, in 2002 federal Medicare spending was $231 billion and for the military was $349 billion. Shoup calculates that the value of off-street parking, at approximately $12,000 per vehicle, roughly equals the total capital cost of all vehicles plus all roads in the U.S.. On a per-mile driven basis, the subsidy for parking amounts to between 5 and 14 cents. Shoup calculates that gasoline taxes would have to be raised by $1.27 to $3.74 per gallon to offset this subsidy, and notes that charging appropriately for parking may be as, or even more effective, not to mention technologically simpler, than other pricing techniques aimed at reducing driving. He cites a study of Boston finds that a $1 parking surcharge would roughly double the average traffic speed in the central business district, the same benefit that would result from a $1 congestion fee. Although part three of The High Cost of Free Parking is dedicated to Shoup’s recommendations, in part one he discusses two solutions which could be implemented relatively easily in the near term: fees in lieu of parking requirements, and offering developers the option to reduce travel demand as an alternative to building a portion of required parking. Fees in lieu of parking requirements allow cities to collect funds from developers to build shared parking facilities. The idea has significant benefits for urban design, largely because it would consolidate parking rather than requiring each establishment to provide a separate lot. Further, because different land uses require parking during different times of the day, a smaller amount of parking can be shared among several establishments. The second solution, reducing demand, offers developers a cost-effective alternative to building more parking. Shoup suggests that employers or developers can offer “eco-passes” as a way to encourage transit use, walking, or bicycling instead of driving. Other demand reduction options are “cash-out parking” (a travel demand management technique which Shoup conceived of years ago) whereby employers offer workers cash in lieu of a free parking space (the employee can spend it to park, or pocket it if another commuting means is available) and car-sharing. Beyond the obvious benefit of diminishing the need for parking and freeing up land for higher end uses, this approach reduces vehicle trips, cutting air pollution, lowering oil consumption, and easing congestion.
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