Historically the parking generation
data has been dominated by isolated, suburban sites in the United
States and Canada. With the update to Parking Generation, we are
encouraging the submission of data for sites with a variety of characteristics
(active TDM, heavy transit use, downtown, shared parking, mixed-use,
bicycle parking, sites with parking cost, as well as isolated,
free-standing single-use sites).
However, as site selection for a
land use moves away from an isolated site, it is most
important to clearly identify all locations where potential
parking demand may be occurring (such as on-street
parking, shared parking areas, adjacent lots, remote employee
lots or other locations where significant parking demand
may be occurring which is not in the immediate site parking
criteria for identifying sites are as follows:
should be transferable; therefore, it is critical that both parking
data and development characteristics be representative of the land
uses to be analyzed.
development should have reasonably full occupancy (i.e., at least 85
percent) and appear to be economically healthy. The percent occupancy at the time of the survey is important,
and should therefore be recorded.
development should be mature (i.e., at least two years old) and
located in a mature area.
- The site should be selected on the basis of the ability to obtain
accurate parking demand data for the land use under consideration.
Locations where total parking
demand can clearly observed for the selected land use (this may
include not only the on-site parking lot/facility, but other
shared/remote lots and/or on-street parking)
should be minimal or no on-site construction or adjacent roadway
should be obtainable from the owner/manager of the prospective
The use of a site vehicle trip
generation count (comprehensive in/out observations) to create
observed parking demand is acceptable only if:
site parking demand was observed immediately
before and/or after the trip generation counts; and
- there is no potential for through trips or
other trips within the trip generation counts (such as
significant vehicle, transit or truck trips of other sites).
Permission of Owner/Manager of Site
Permission to conduct a parking generation survey should
always be requested from the owner/manager of a prospective
survey site. The purpose and details of the survey should be
fully explained. An offer should be made to share the results of
the survey with the owner/manager.
Provision of an independent
variable is essential to estimating parking demand
ratios. Physical and functional characteristics of the site
(e.g., number of acres, gross floor area, number of employees),
that are not evident from a site inspection may be obtained from
the owner/manager. Other sources of site data may include
developers, architects, planners, government offices,
consultants, realtors, assessors, or the home office of the
development. The owner/manager should be able to furnish details
of transit service and utilization of car or van pools. The
owner/manager should also have a good idea of the days and hours
of peak parking demand. An important statistic for the surveyor
to ascertain is the occupancy of the site under study. The
percentage of office space being utilized, the number of
apartment units occupied, the number of spectators at a sporting
event, etc., have a direct bearing on the parking generation
rates. If all of the data cannot be obtained, provide as much as
possible and complete the survey.
For shopping centers it
has been found that parking demand can vary significantly with
the percentage gross square feet devoted to restaurant or
entertainment activity. This additional variable should be
collected as part of the survey and recorded in the data
forms under "Notes". Restaurants would include
any eating/drinking establishment, fast food restaurant or other
food service related activity. Entertainment would include
any theater space, amusement park, night club or other
entertainment activity. This information should be
provided with any shopping center (land use code 820) survey,
shown as a percentage (%) of the total gross square feet of
shopping center area.
The objective of the survey is to count the number of
vehicles parked at the time of peak parking demand. It is
valuable to provide parking demand data for other hours of the
day to establish the variation of parking demand over the hours
of the day, but observation of peak parking demand should be the
objective of each survey.
Usually one can predict when peak parking accumulation will
occur. Examples would include:
- residential land use would generally peak at
night or very early in the morning,
- restaurants at meal times (noon time and dinner
- office or employment uses typically peak in the
mid-morning or mid-afternoon, and
- stadiums during capacity crowd events.
Peak parking accumulation at other types of land uses may be
uncertain. These may require spot counts at specified intervals
such as every one-quarter, one-half, one, or two-hour intervals
throughout the day or portions of the day in order to assure
accurate data. While multiple observations may be performed in
one hour, only the highest observed parking demand for each hour
should be entered on the parking demand survey form. Correlating
the parking demand observation to the hour of day that the
survey was conducted is critical element of the parking
generation data. The parking survey should also be
sensitive to the fact that land uses may exhibit different
parking trends from day to day. For example, a sales oriented
office may show higher parking demand on Monday mornings and
Friday afternoons than during the mid-week when the sales force
is out of town. List all information on the parking demand
survey form including any observations or characteristics of the
site that would be of interest. The web-based data entry form
asks questions with pull-down selections about site
characteristics that are important for consideration of parking
demand (eg. parking
costs, type of surrounding
For sites with complex characteristics (TDM, extensive transit
use, shared parking, bicycle parking) a separate web-data entry
form is being developed (under construction at this time).
Many agencies and consultants have existing parking occupancy
survey data on file. You are urged to use that data and fill out
the survey form so that as much data as possible can be
available in the ITE data warehouse of parking generation.
Again, it is not imperative that all data questions be answered;
provide as much as possible and forward the data to ITE.
New parking demand surveys are needed to enhance the
statistical value of the parking generation data. It is highly
recommended that when a trip generation survey is conducted for
a site, that parking demand observations also be performed. ITE is working cooperatively with
universities and ITE Student Chapters to conduct parking demand
surveys on an annual basis. For information regarding this
program, please contact Lisa Fontana Tierney at firstname.lastname@example.org.
There are three ways to submit
parking data. The Excel
spreadsheet is the preferred method of submission.
However, if a prior study was completed with all the required
background data, those studies can be submitted via mail to ITE
Parking Generation Survey
Institute of Transportation Engineers
1627 Eye Street, NW, Suite 600
Washington, D.C. 20006
If you have any questions, do not hesitate to contact
Lisa Fontana Tierney.