Civil Engineering Reference
In-Depth Information
Chapter 14
Overview of Congestion Relief Strategies
14.1 Introduction
Keeping congestion manageable is essential, since excessive congestion can
adversely affect a community
s livability and economy. A basic objective of con-
gestion-relief actions is to reduce congestion to manageable levels since its com-
plete elimination is neither practical nor cost-effective in large urban areas.
There are two basic categories of traf
'
c congestion that should be addressed:
nonrecurring and recurring.
Nonrecurring congestion
is characterized by the occurrence of
unexpected
events that reduce road capacity e.g., vehicle crashes and other vehicle break-
downs, inclement weather, work zones), emergencies, or by surges in traf
c
demand that temporarily exceed roadway capacity.
Recurring congestion
results from
expected
increases in demand at locations
where it exceeds roadway capacity during known time periods such as the am
and pm peak hours of travel. It also results from reductions in capacity at known
locations where there is an imbalance in lane continuity (e.g.,
three lanes
merging into two lanes).
This chapter overviews the various ways to better manage congestion. It pro-
vides the context for various congestion relief measures that are presented in the
chapters that follow. They give more details on the applicability, user bene
ts, user
costs, and other effects, as well as public acceptance of capacity enhancement/
expansion strategies, and travel demand reduction strategies.
Congestion relief actions should be keyed to the needs, opportunities, and
resources of each urban area. Relevant considerations include:
the location and extent of congestion
the character of the development pattern and its transportation connectivity
the number, size, and complexity of the various governmental jurisdictions and
public agencies involved
