&EPA
United States
Environmental Protection
Agency
Air and Radiation
EPA420-S-98-OO8
July 1998
Office of Mobile Sources
TRAQ Technical Overview
Transportation Air Quality Center
Transportation Control Measures:
Parking Management
EPA's main strategy for addressing the contributions of motor vehicles
to our air quality problems has been to cut the tailpipe emissions for
every mile a vehicle travels. Air quality can also be improved by
changing the way motor vehicles are used—reducing total vehicle miles
traveled ait the critical times and places, and reducing the use of highly
polluting operating modes. These alternative approaches, usually
termed Transportation Control Measures (TCMs), have an important
role as both mandatory and optional elements of state plans for
attaining the air quality goals specified in ~the"Clean Air Act TCMs
encompass a wide variety of goals and methods, from incentives for
increasing vehicle occupancy to shifts in the timing of commuting trips.
This document is one of a series that provides overviews of individual
TCM types, discussing their advantages, disadvantages, and the issues
involved in their implementation.
> Printed on Recycled Paper
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Contents
O Background
© Costs and Benefits
© Implementation
O Equity Issues
O Examples
©Sources
• On-line Resource?
Parking management is a transportation control measure
(TCM) that administers the supply of available parking
spaces. The goal is to limit and allocate the overall number of
vehicle parking spaces in a particular area (e.g. a downtown
commercial/retail district) which will in turn encourage SOV
users to switch to other means of travel. Common forms of
parking management include:
fc* Limiting total available parking
*»• Providing preferential parking for desired travel modes
such as commuters or vanpools
**• Setting minimum or maximum parking space ratios in zoning ordinances
r-i • -• .*£&<• •*' - '.: ' "'• SS
*+• Implementing time limits on existing vehicle parking spaces
(Raising parking fees directly is also a form of supply management; this topic is addressed in a
separate summary sheet.)
•, ^
Portland, Oregon was one of the first
areas to implement parking
management ;as a TCM by limiting the
numBer of available packing spaces.
1. Background
Most urban areas have some form of
parking management. However, few of these
areas have attempted to limit the number of
available spaces or provide incentives for non-
SOV forms of travel. Portland, Oregon was
one of the first cities in the U.S. to limit the
parking supply as a trip reduction strategy by
setting a maximum parking space requirement that developers may not exceed. This is contrary
to requirements in many areas that specify a minimum number of spaces that developers must
create.
In the private sector, many employers may provide preferential parking for carpoolers,
(e.g., GEICO in Bethesda, Maryland, Hallmark Cards in Kansas City, Missouri, and the Pentagon
in Northern Virginia). These efforts may be performed voluntarily, or be required under a local
trip reduction ordinance.
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Parking Management
Page 2
2. Costs and Benefits
Parking management strategies result in air quality benefits when travelers choose an
alternative method to SOV travel because of preferential parking for that mode or limited parking
availability for SOV travel. The impact of parking management measures on SOV travel is
difficult to quantify because the measure is often implemented in conjunction with additional
congestion management or air quality improvement measures, and it is difficult to separate the
impacts of this measure alone from the overall program.
One way to estimate the air quality impacts of limited parking availability is to estimate
the increase in parking prices that is likely to occur due to reduced parking supply, and derive the
estimated impact on driving behavior from this price increase. Note that this method requires
that reliable estimates of demand elasticity for parking for the area in question be available.
Another method is to determine the ratio of parking spaces to employees in a given area,
and compare this to ratios in similar areas without parking management policies (or similarly, to
determine the ratio before a parking supply policy was in effect and sometime after it has gone
into effect). Each parking space that does not exist due to the parking policy can be assumed to
result in one fewer vehicle round trip, if the space would have been used and if used once per day
(this can vary according to local situations). An average VMT per trip can be determined to give
a total estimated VMT reduction. A ratio of parking spaces to square footage of development,
rather than employees, can also be used.
An additional benefit of limiting
parking space may result from the potential
higher economic use of land that would
otherwise be used for parking. However, an .
unintended consequence is that drivers may
circle an area frequently in search of parking,
which could lead to increased congestion.
Also, vehicles could be drawn to fringe,
retail-only, or residential parking, which may
be undesirable for residents and require further enforcement and signage needs.
Costs of-this measure include those incurred for administration of a program, and for
enforcement if the measure is required. Additional costs may include the costs of building
facilities for preferential parking, signs, and parking booth attendants if they are required.
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Parking Management ^ Page 3
3. Implementation
Parking management measures may be.required by ordinance or they may be voluntary.
The measure does not require a substantial amount of financial resources to implement, although
a large amount of political capital may be required to overcome business and employer
objections to reducing or limiting available parking. To implement overall parking limits, an area
may need to conduct parking surveys and studies, and develop and seek input on plans.
Implementing mandatory parking supply
reductions may be unpopular with
merchants, employers, or residents and
require consensus building to implement
a policy that is generally accepted. '
Areas that already have a
comprehensive parking plan for a downtown
or suburban area may already have the
necessary experience, personnel, and
resources to effectively implement a parking
supply program. Start-up may be relatively
quick or may take longer, depending on the
specifics of the measure. Implementing
mandatory parking supply reductions may be
unpopular with merchants, employers, or residents and require consensus building to implement
a policy that is generally accepted. Parking supply ordinances imposed on developers may be
less contentious, as developers often prefer to avoid the use of available real estate for parking
purposes. Creating preferential parking for high occupancy vehicles (HOV) users requires
enforcement if the measure is to be effective.
Policies that limit available parking supply work best where the following conditions are
met:
*»• Current parking is well utilized (where supply doesn't greatly exceed demand).
*»• Transit, bicycle and pedestrian, and ridesharing facilities and programs exist to
absorb commuters that no longer drive.
*•»• Vacant land and neighborhoods do not have the capacity to absorb the overflow or
are well controlled by parking restrictions.
4. Equity Issues
Parking policies generally affect all groups of commuters equally. Those already using
public transit or with access to it may be inconvenienced the least. Those who must drive may
bear more of the cost because they will be required to pay higher parking fees which usually
result when the parking supply is limited. Commuters who are able to carpool or vanpool may
benefit the most from preferential parking for HOVs. Urban residents may find that residential
parking becomes limited if overflow parking is not controlled.
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The success of the Portland,
Oregon parking policy is due to
the implementation of maximum
parking ratio measures for new
office development
Parking Management :' Page 4
5. Summary of Recent Examples
The Portland, Oregon example discussed
above has been in effect since 1975 and has been
documented. The Portland parking policy has relied
upon implementation of maximum parking ratio
measures for new office development for much of its
success. This policy specifies maximums of 0.7 to
1.0 parking spaces per 1,000 square feet, based on
type of development and proximity to transit. This
compares with typical office developments that provide about 4 parking spaces per 1,000 square
feet. In addition, no new parking facilities can be built for existing development, except in the
case of major renovation.
An estimate of the emission reduction benefits of the Portland policy found that VMT
reduced due to the policy, in 1995, totaled between 50,960 and 92,000 miles per day. This VMT
reduction resulted in a drop in fuel consumption of between 2,610 to 4,730 gallons per day, and a
greenhouse gas reduction of 2,400 to 4,400 metric tons of carbon equivalent per year. Since the
policy has been in effect, the downtown Portland job base has grown significantly.
Seattle, Washington requires developers in the downtown area to set aside a minimum of
20 percent of new parking spaces for carpoolers at employment sites. Results are mixed, with
the preferential spaces receiving little use on a regular basis. Sunnyvale, California has
implemented a similar program, with similar mixed results. EPA's Office of Mobile Sources in
Ann Arbor, Michigan sets aside preferential parking for carpoolers. The spaces are usually full.
San Francisco, California has a long standing policy that allows only seven percent of a
building's gross floor space to be used for parking. In addition, new development cannot receive
an occupancy permit without an approved parking plan. Planners in the city found that in the
past ten years there has been no major increase in peak traffic in the area even though office
space growth has been considerable.
6. Sources
[1] U.S. Department of Transportation. Parking Supply Management Factsheet. Obtained from
the U.S. DOT/FTA Internet web site (www.fta.dot.gov).
[2] "Reducing Greenhouse Gas Emissions Through the Transportation Partners Program: Recent
Trends and Case Studies." Prepared for U.S. EPA, Office of Policy, Planning, and Evaluation.
(September 22, 1995).
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Parking Management Page 5
7. An On-line Resource
The Environmental Protection Agency's Office of Mobile Sources has established the
TCM Program Information Directory to provide commuters, the transportation industry, state and
local governments, and the public with information about TCM programs that are now operating
across the country. This document and additional information on other TCMs and TCM
programs implemented nationwide can be found at:
http://www.epa.gov/omswww/transp/traqtcms.htm
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