Deciding on Needs
Determining the right amount of parking is always a delicate balancing act, between the need for access in an auto-oriented world and the desire to minimize traffic and the sometimes harmful impacts that autos bring. Many communities are concerned about the negative impacts of having too little parking – neighbors complain, cars are parked illegally, shop owners worry about discouraging patrons, lenders and developers worry about the desirability of their properties, drivers waste time hunting for parking spaces. Recently, though, some communities have begun to realize that too much parking can be as detrimental to the community as too little, and have taken steps to reduce parking requirements and improve the efficiency of existing parking.
There is no simple, correct answer on how much parking is needed. The answer for your community will depend on the area of interest (town and neighborhood centers will have different needs than stand alone developments), the access available to that area (less parking is needed for locations with good walk and transit access), and the type of development existing or planned (residential parking needs are greatest overnight, office during the day, and some retail uses will need the most parking on weekends). Where there is a mix of uses parking can be shared. But the answer to parking needs is also a local policy choice – to invest in auto-oriented versus transit and pedestrian transportation options, to concentrate development or to spread out, and how best to maximize local tax revenues. The best way to understand the parking needs in your community is to start with a survey of the existing parking situation. Whether your concern is parking in the town center or how much parking to require of a new development, you need to know have much of what types of parking is currently available and how is it used. In most cases, the survey should include both public and private parking, on-street as well as off-street spaces. Many simple counts can be accomplished by local volunteers, and traffic consultants are usually available for the more complicated of estimating future demand. Basic guidance on how to do a parking study and examples of some recent local studies are available in this toolkit.
Besides providing counts of existing use, surveys are also helpful in determining community priorities. Many communities have used surveys of local businesses to help determine parking needs. Convening a community parking or transportation committee is another common approach, allowing many different voices to be heard and to work together for a solution.
Parking requirements should always be tailored to the type and size of development, the location and uses surrounding the development, and the transportation options available nearby. A retail use in a walkable downtown served by transit will need far few spaces than a comparable use located on a highway.
Setting Minimum Standards
Minimum requirements are still the most common parking standards. For each different use allowed by zoning a minimum number of spaces is required, based on the size of the building, number of residential units, number of seats in a restaurant, etc. This link provides a typical example, from Somerville. A new development or use can provide more parking spaces if desired. Typically these minimum standards come from information collected and published by professional organizations such as the Institute of Transportation Engineers (Parking Generation) and the American Planning Association (Parking Standards). In other cases, communities adopt the same standards as their neighbors.
These minimum standards have the advantage of being widely used and legally defensible. They usually require sufficient parking that spillover into surrounding neighborhoods is not a problem. However, most of the parking studies on which these standards are based were done at single use, low-density suburban locations, where parking was free and unlimited and walking, biking, and transit options were limited. Parking was usually counted at times of maximum demand – peak shopping days for retail parking, for example.  If that reflects the type of location and parking situation that you are planning for then minimum standards may meet your community’s needs.
A parking study can also be used to establish minimum standards. Measuring the demand for parking on a average day establishes the minimum parking needed, based on local conditions.
Alternatives to Minimum Standards
Minimum standards frequently lead to an oversupply of parking, with unused spaces on all but the highest demand days. This is costly for the developer and wasteful for the community and encourages auto use. These requirements may be limiting downtown redevelopment or increasing the cost of providing affordable housing. In some situations, the best way to address this is simply to eliminate minimum parking requirements for certain land uses or certain areas, such as in the downtown, near transit stations, or for affordable housing developments. Locally, several communities including Ipswich and Gloucester have eliminated parking requirements for sites within a certain distance of a municipal parking lot in the downtown. A number of cities across the country have also eliminated required minimums throughout the Central Business District, including San Francisco and Portland, Oregon.
The key to success when eliminating minimum parking requirements is to minimize the potential for spillover effects – this is, after all, what the minimum requirements are intended to do – and ensure that there are other ways for people to access the site. Having some paid parking garages or lots nearby that are not at full capacity and access to the site via non-auto modes increase the chances of success. However, even if those pieces are in place, there will likely still be a need to control spillover effects.
One of the main concerns is generally spillover into nearby residential districts’ on-street parking. This can be addressed with a residential permit parking program. Residents may resist the transition to permit parking, but one way to win them over is through residential parking benefit districts, which charge non-residents to park in unused resident spaces, and return the revenue to the neighborhood for improvement projects. On non-residential streets, eliminating minimum parking requirements without charging for on-street parking can lead to a shortage of curb parking spaces, and the associated problems with drivers circling endlessly seeking a space, even when there are many spaces available in nearby parking garages. The solution there is to charge market prices for on-street parking. The revenue collected from on-street meters can be returned to a Parking Benefit District or Business Improvement District for improvement projects.
Another concern is that if new developments (or redevelopments) are not required to provide parking where previous developments were, the burden of providing parking may be unfairly distributed on the properties that have been there longer. If this is a concern, one alternative is to maintain required minimums but allow developers to pay a fee in lieu of each required space not provided, with the fees to be used for providing public parking. Another alternative is to allow those with an existing parking supply that exceeds their needs to rent or sell it to newcomers who can’t add parking to their sites. In some cases, developers may be constrained by requirements from lenders that they provide a certain amount of parking. For more on making the case to lenders, click here.
If your community is not ready to drop minimum parking requirements altogether, other options include establishing flexible parking requirements, allowing shared parking, setting parking maximums in addition to minimums, and allowing spaces to be held in landscaped reserves. When a local parking study is not available, the standard minimums can also be adapted for local conditions using the Parking Requirement Adjustment Factors included in the parking study section.
1.Christopher V. Forinash, Adam Millard-Ball, Charlotte Dougherty and Jeffrey Tumlin. Smart Growth Alternatives to Minimum Parking Requirements