Civil Engineering Reference
In-Depth Information
Examples of parking supply requirements in three cities are shown below.
1.0 spaces/1,000 ft
2
of of
Portland
had a limit of 0.7
floor area. With this
limit the transit share accounted for 48 % of all CBD arrivals. Before the limit
this percentage was 45 %
ce
fl
-
Seattle
with a maximum rate of 1.0 space/1,000 ft
2
of of
ce
fl
oor area; a
minimum rate of 0.54 spaces/1,000 for areas with
“
good
”
transit service; and
0.75 spaces/1,000 for areas with moderate transit service.
San Francisco
has 45,000 parking spaces for 250,000 employees. No more than
7 % of buildings
'
gross
fl
floor area can be used for parking.
Table
22.3
compares the experiences of six US cities that have managed their
downtown parking ratios.
22.2.3.2 Complementary Actions
Managing parking supply to reduce congestion in city centers and in other major
activity centers requires several complementary actions. These actions include
establishing time restrictions on the availability of on-street parking and imple-
menting residential permit programs.
In addition, locating peripheral parking facilities adjacent to downtown areas can
reduce the number of vehicles searching for parking spaces on downtown streets.
Where these lots and garages are located within one mile of the CBD, most parkers
can walk to their CBD destinations. A good example is Chicago
'
is Grant Park lots
and garages that are located just east of Chicago
s Loop. These facilities have direct
access to Lake Shore Drive and Michigan Avenue. But like other peripheral parking
facilities they do not reduce Chicago
'
'
s peak hour radial freeway congestion.
22.2.4 Managing Suburban Parking
Expanded commercial and residential developments in suburban areas have increased
suburban traf
c congestion. Abundant, relatively inexpensive land fostered low
density spread out development for nearly 50 years, creating auto-oriented suburbs.
Early suburban developments were characterized by large tracts of single family
houses, planned regional shopping centers, and industrial parks. The rapid suburban
growth since the 1980s included large of
ce parks and mega centers. Suburban
developments serve single purposes (e.g., residential, retail, of
ces, etc.) and are
surrounded by large parking areas mandated by zoning requirements. Often streets are
inadequate to serve the concentrated demand volumes; and transit service is of poor
quality. These conditions result into severe peak-hour suburban traf
c congestion.
The amount, location, and design of parking facilities have a strong in
fl
uence on
suburban traf
c congestion. Traf
c volumes are usually keyed to number of parking
