Civil Engineering Reference
In-Depth Information
Table 23.10 Comparative
trip generation rates for
suburban and transit-oriented
developments
Vehicle trip rate 24 h AM peak hour PM peak hour
TOD 355 0.28 0.39
ITE 667 0.54 0.67
% 53.3 51.3 0.58
Source
Reference [
22
], Tables 2.2 and 2.3, Washington DC, 2008
In the long term, land use strategies that encourage travel alternatives to the car,
can provide meaningful reductions in regional VMT growth at low cost to the
public sector and some congestion relief. Modest to moderate changes in land use
patterns can be accomplished without signi
cant loss of consumer choice. For more
widespread acceptance of smart growth land developers and elected of
cials need to
believe that there is a demand for the type of life style smart growth offers, and
widespread acceptance of this concept is still to be determined.
23.8 Conclusions
The following congestion-related key conclusions emerge from this chapter.
1. Public transportation improvements can increase transit ridership, reduce car
trips, and increase population and employment densities.
2. High employment and residential densities are desirable to minimize VMT and
to maximize pedestrian and transit trips. But increasing densities may increase
traffic congestion because compact land uses that generate less VMT per person
generate higher traf
the most compact cities also
tend to be the most congested. An illustration of this phenomenon for the San
Francisco Bay Area was shown in Table
23.2
.
3. Land use generates travel demand. Its density and mix of uses determines the
type of transportation system that best serves this demand. Putting people into
fewer vehicles by increasing land use densities, encouraging walking and bik-
ing, and/or eliminate the need to travel (through telecommuting and teleshop-
ping) reduces the VMT and can reduce freeway congestion.
4. Local zoning changes can contain and possibly reduce traf
c density (VMT/square mile)
—
c congestion espe-
cially over the long run. Key actions include (1) downsizing zoning for com-
mercial land, (2) discouraging strip developments, (3) coordinating access
management with corridor development, and (4) requiring major activities to
have good pedestrian and transit access.
5. VMT and congestion reductions from the various actions associated with public
transportation and land development will become especially important in the
long run as urban areas grow. These actions can provide the framework for
creating more livable, sustainable, and accessible communities.
