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SA Page 40 The problems with parking requirements have only began to surface in recent years. Donald Shoup has written extensively on the subject. The following excerpt from his paper The Trouble With Minimum Parking Requirements explains how the current situation came to be. Practicing planners use simple empirical methods to set minimum parking requirements. In one of the few attempts to explain how parking requirements are set, Robert Weant and Herbert Levinson (1990, 35, 37) say: Most local governments, through their zoning ordinances, have a parking supply policy that requires land uses to provide sufficient off-street parking space to allow easy, convenient access to activities while maintaining free traffic flow. The objective is to provide enough parking space to accommodate recurrent peak parking demands... .. .For the purpose of zoning ordinance applications, parking demand is defined as the accumulation of vehicles parked at a given time as the result of activity at a given site. In effect, planners count the cars parked at existing land uses, identify the highest number counted as peak demand (without consideration of price), and then require developers to supply at least that many parking spaces (without consideration of cost). Planning for parking is planning without prices. The only source of data that systematically relates parking demand to land use is Parking Generation, published by the institute of Transportation Engineers (ITE). The ITE (1987) reports the "parking generation rate" for 64 different land uses, from airports to warehouses. The parking generation rate for each land use is defined as the average peak parking demand observed in case studies: , a vast majority of the data.., is derived from suburban developments with little or no significant transit ridership .... The ideal site for obtaining reliable parking generation data would ... contain ample, convenient parking facilities for the exclusive use of the traffic generated by the site .... The objective of the survey is to count the number of vehicles parked at the time of peak parking demand (ITE 1987, vii, xv; emphasis added). Half the reported parking generation rates are based on four or fewer case studies, and 22 are based on a single case study. The case studies do not refer to parking prices, but most parking must be free because the 1990 Nationwide Personal Transportation Survey found that parking is free for 99 percent of all automobile trips in the United States (Shoup 1995). The ITE parking generation rates therefore measure the peak demand for free parking observed in a few case studies conducted in suburban locations with little or no public transit. Planners often set minimum parking requirements higher than the ITE parking generation rates. For example, a survey of 33 cities in nine southeastern states found that parking requirements averaged 3.7 spaces per 1,000 square feet of office space, or 32 percent higher than the ITE parking generation rate of 2.79 spaces per 1,000 square feet (Polanis and Price 1991, 32). Similarly, a survey of 117 cities in California found that parking requirements averaged 3.8 spaces per 1,000 square feet of office space, or 36 percent higher than the ITE parking generation rate (Shoup 1995, 18). ~g~e ~~ -~---. _ .~, _._h .--'"-.-...-- .,-_.~._._.-.---,-_.."..~.~-----_."._-