Accessory parking provision requirements
Accessory parking provision requirements, also known as mandatory parking minimums, are policies to require a minimum number of parking spaces to be provided as an accessory to the construction or expansion of a building. The goal of accessory parking provision requirements is to ensure that each development in an area contributes to providing its fair share of off-street parking space, under the theory that, if left to their own incentives, each individual developer would under-provide parking in a "tragedy of the commons" by overly relying on street parking, thus contributing to a collective neighborhood parking shortage. As an example, if a developer wishes to construct a multi-family dwelling, under accessory parking provision requirements, a commensurate portion of the building itself or the lot on which it is built must be reserved for a garage or parking lot. In determining the amount of parking required, regulations may consider factors such as the neighborhood density, building use type(s), and surrounding area transit infrastructure. Requirements for residential buildings are typically based on the number of units, whereas requirements for retail spaces are often based on square footage. The formulae used to calculate minimums often vary between cities and suburbs, and across neighborhoods based on zoning. Jurisdictions may also apply a given set of exemptions to parking requirements in order to provide greater development incentive where the provision of accessory parking is not warranted. As one example of how such parking requirements may vary, in the New York City Borough of Staten Island, an average of 122 parking spaces is required for every 100 units, whereas, in the Borough of Manhattan, developments are largely exempt from any parking provisions due to its higher density and existing subway, bus, taxi and bicycle transit resources.  Recently, as many urban areas have shifted their policies away from a car-oriented design and toward a more transit-friendly design--and, thanks to multiple studies which have shown that such parking provisions often result in excess empty parking spaces--many cities are updating their policies by lowering accessory parking requirements or even eliminating them altogether. 
- Goal: Increase the rate of automobile use
- Goal: Increase the surface area of available roads
- Goal: Increase the efficiency of automobile parking use
- Goal: Decrease the rate of automobile theft, terrorism, and other violent incidents
- Goal: Increase automobile parking capacity
- Goal: Increase the rates of automobile transportation user comfort, convenient and satisfaction
- Goal: Increase the fuel efficiency of automobile transportation
A local jurisdiction wants to redevelop a neighborhood. Currently, there is little public transportation or foot traffic, and relatively few people live in the area. The jurisdiction decides to rezone the neighborhood for mixed use, allowing for the development of residential, office, and commercial spaces. In determining minimum parking requirements, the jurisdiction keeps an eye to the future with plans for increased bike lanes and an expansion of public transit. It sets rules for residential buildings which require not only parking spaces for cars but for bicycles as well. It also allows for shared parking between residential and office spaces, knowing that peak use for each will be at different times. It takes into consideration the different types of anticipated commercial spaces and greater variance in square footage, allowing for more flexibility in the requirements rather than generic rules. By creating mixed zoning and providing for greater flexibility in parking requirements, the jurisdiction enables the development of a vibrant and diverse neighborhood with multi-modal transportation options.
The city of Houston's original accessory parking provision requirements, which it calls its Off-Street Parking and Loading Ordinance, was adopted in 1989. As the city grew over the next two decades, the ordinance remained unchanged even as more and more exemptions to the requirements were granted for various developments. Finally in 2013, Houston's City Council approved numerous changes to the Ordinance. This was done in the interest of easing the burden on businesses. Whereas the original Ordinance had only differentiated between bars and restaurants, the new rules created eight categories based on the type of establishment and each category has a different requirement which is based on the business's square footage. As a result, take-out restaurants for example are no longer required to provide the same number of parking spaces as sit-down restaurants. Furthermore, the rules take into consideration shared parking options, and require the provision of parking spaces for bicycles in addition to cars. Providing bicycle parking in excess of the minimum requirements allows for a decrease in the requirements for car parking. Such rules provide increased flexibility for developers and decrease the burden on business owners, and in turn help mitigate the potential increase in car volume which may result from access to off-street parking. Additionally, if an establishment is providing off-site parking, the new rules increase the distance allowed between the two locations and enables an additional increase contingent on the provision of adequate pedestrian amenities. As with the rules regarding bicycle parking, such rules allow for flexibility and benefits that reach beyond the immediate business and its patrons.  
Tradeoffs of implementing this policy may include:
- Encouragement of private car ownership and use, which may increase congestion.
- Reduced density for dwelling units as a result of space needed for parking.
- Increased home prices to offset fewer possible homes/residents.
- Disincentivizes the use of public transportation.
- Reduced walkability for area residents.
If answered yes, the following questions indicate superior conditions under which the policy is more likely to be appropriate:
- If a residential development, are anticipated residents likely to be car owners or require a car?
- Is there inadequate street parking to accommodate residents, employees, or patrons who own cars?
- Are mass transit options unavailable within close proximity of the property?
- Is the free market failing to adequately encourage the provision of parking spaces by developers without mandated parking provisions?
- Are the requirements such that they do not result in a reduction of anticipated profits which would discourage development?
- Are the requirements such that they will not result in an unacceptable increase in housing costs?
Assuming that a jurisdiction has decided to adopt the policy, the following questions will need to be answered when determining how to implement this policy:
- What type of facility is being constructed?
- Parking provisions should be based on the number of units for residential properties and square footage for others.
- For residential developments, what is the anticipated ratio of cars owned to units?
- Is on-street parking available, and would it be able to accommodate new incoming residents, employees, and patrons?
- What is the goal of the development?
- It is necessary to evaluate to what extent increased density and/or economic development are goals of the project.
- This may affect whether the area should be rezoned for mixed or single use, which in turn would be best benefited by a greater or lower number of mandatory parking spots.
- Is there access to public transit and/or bike lanes in proximity to the development?
- If there are non-private car transportation options in proximity, lower requirements may be preferable so as not to discourage the use of other modes of transportation and to minimize congestion increases.
- If satisfying the parking provision requires building ground-level parking, is there sufficient space on the lot to do so?
- Can a garage be constructed or would the developer have to provide a parking lot?
- Would adequate space remain for acceptable-sized housing units if a portion of the surface area must be devoted to parking?
- Is the cost of supplying parking prohibitive to the developer?
- Providing underground parking would allow for a greater amount of residential units or square footage for commercial or office space.
- However, bedrock or existing infrastructure may make providing subterranean parking impossible or too costly.
- Is the lot on which the development is being built of a sufficient size to permit the construction of both the main and parking facilities?
- Can the developer be sure of recouping the upfront costs of providing off-street parking?
- In order to not discourage development, developers must be assured of earning an adequate profit.
- Providing surface level parking will result in less square footage available to sell or rent, which in turn means lower profits or higher prices.
- However, prices cannot be allowed to increase so much as to become prohibitive for those looking to buy or rent in the new development.
- Has adoption of: Common.
- For governance level(s): Local.
- Notable entities who have implemented or adopted this policy include:
- City of New York - With different provisions for different boroughs, requires from an average of just 5 to 122 off-street parking spots for every 100 housing units.
- City of Chicago - Generally requires one parking spot per housing unit, and one parking spot per two housing units in for residences in proximity to a public transportation stop. 
- City of Denver - Requires off-street parking for new developments, and has issued a moratorium on an exemption to the requirements for small lots. 
- City of Houston - Increased the number of categories which have different parking requirements, requires provision of bicycle parking, and allows for parking minimums to be reduced if offset by more bicycle parking. 
- Advocates - Automobile Transportation. Assumption: Provision of parking spaces will ease and thus encourage private car use and ownership.
- Constituent Groups - Commuters. Assumption: A car is deemed necessary for at least a portion of the commute.
- Constituent Groups - Local Residents. Assumption: Frees up on-street parking.
- Constituent Groups - Automobile Clubs and Owners. Assumption: Eliminates the need to search for on-street parking, or to find paid parking.
- Constituent Groups - Public Housing Residents. Assumption: May not be able to afford a car if living in public housing.
- Advocates - Urbanism. Assumption: Increased parking encourages car use and therefore may discourage the use of other modes of transportation by decreasing the efficiency of bus transit and reducing walkability.
- Advocates - Mass Transportation. Assumption: Increased parking encourages car ownership and increased driving, reducing mass transportation efficiency and demand.
- Advocates - Environmental Protection. Assumption: Increased parking encourages car ownership and increased driving.
- Associations - Building and Construction. Assumption: Upfront costs are increased and may not be recouped.
- Searching for the Right Spot: Minimum Parking Requirements and Housing Affordability in New York City. NYU Furman Center for Real Estate and Urban Policy. March 2012. The study found that parking provision requirements result in developers providing more spaces than they actually believe will be demanded, which in turn increases prices.
- Subsidizing Congestion: The Multibillion-Dollar Tax Subsidy That’s Making Your Commute Worse. TransitCenter and Frontier Group. November 2014. This report found that there is significant increase in the use of private cars due to subsidized parking, and this increase is not offset by benefits for transit use.
- Space City: Houston City Council approves a new parking ordinance (2013)
- City of Houston May Change Parking Requirements for Restaurants, Bars and More (2011)
- Searching for the Right Spot: Minimum Parking Requirements and Housing Affordability in New York City. NYU Furman Center for Real Estate and Urban Policy. March 2012.
- Buffalo Becomes First Major U.S. City to Eliminate Parking Minimums. StreetsBlogUSA. January 2017
- Space City: Houston City Council approves a new parking ordinance. Lexology. April 2013.
- City of Houston May Change Parking Requirements for Restaurants, Bars and More. Houston Press. October 2011.
- New TOD Ordinance Will Bring Parking-Lite Development to More of Chicago. StreetsBlogChicago. September 2015.
- Denver’s Housing Shortage Is Getting Worse Thanks to City Council’s Parking Obsession. StreetsBlogDenver. March 2017