Recap and Concluding Observations - Road Traffic Congestion - page 373

Congestion relief strategies and related actions vary with (a) the type of conges-
tion; (b) city size, structure, and street patterns; (c) the location, type and severity of
speci

uenced by
agency and community support, and the availability of available resources.

c problems, and (d) the likely future traf c growth. They are also in fl

24.6.2 Strategies that Relieve Nonrecurring Congestion

For nonrecurring events the strategies include shortening response and recovery
times for incidents and real-time information to minimize adverse impacts on
travelers. To accomplish these objectives two critical elements are necessary: (1)
the application of ITS technologies (e.g., real-time information, fast computing
algorithms, and communication) whose key function are to provide early detection
of a random event(s) and inform responding agencies and travelers about its
location, and travel alternatives, and (2) the coordination of functions among
responding agencies.
Reducing the intensity, duration, and extent of congestion created by non-
recurring events involves the application of supply strategies (adaptation) and
demand management strategies (mitigation) that are responsive to the type of event
that reduces capacity or increases demand. Strategies suitable to manage the
impacts of nonrecurring events involve the ability to detect the event as soon as it
happens and to restore the roadway to full capacity as soon as possible; direct
drivers to reduce speed during inclement weather or when the roadway is being
repaired; mitigation strategies involve informing drivers about the location and
times of special events that are likely to generate surge in traf

c demand on the
impacted roads so that they may plan changes in trip time, or route.
Strategies that reduce the impacts of non-recurring congestion delays involve the
ability to detect the event as soon as it happens and to restore the roadway to full
capacity as soon as possible, direct drivers to reduce speed during inclement
weather or when the roadway is being repaired, or inform drivers about the location
and times of special events that are likely to generate surge in traf c demand on the

impacted roads. Safe and speedy evacuation is essential when major disasters occur.

24.6.3 Strategies that Relieve Recurring Congestion

Strategies that relieve the impacts of recurring congestion, include increasing the
operational ef ciency of existing road networks, creating new capacity, and man-

aging (reducing) highway travel demand.
Strategies that reduce recurring congestion delays at physical bottlenecks
involve grade separation of intersecting traf c streams; road widening at bottleneck

locations; the addition of merging and turn lanes; and recon

guration of entrance
and exit ramps at freeways and expressways. However, to prevent new traf c