Civil Engineering Reference
In-Depth Information
Fig. 14.3 Extent and duration of traf
c delay when peak hour demand exceeds roadway capacity
c demand exceeds capacity for only 1 h, Fig.
14.3
shows that
congestion delay on the approach roadways lasts 2 h (from 8 to 10 am), adding an
average trip delay of 15 min to each of the 8,000 (14,000
Although traf
6,000) vehicles delayed
with a maximum trip delay of 30 min experienced by those vehicles arriving at 9
am.
-
14.4.1.1 Possible Strategies
Relief strategies that focus on minimizing the congestion impacts caused by the
recurring peaking of traf
c demand have traditionally involved expanding roadway
capacity (and transit capacity where appropriate) to meet demand peaks. However,
this approach is dif
cult to achieve in built-up areas because space for capacity
expansion is dif
financial resources are often inadequate.
When these conditions prevail strategies that focus on the reducing private vehicle
demand volume during the peak hours are required. These include, for example,
peak spreading through
cult to obtain and existing
flexible work hours, peak hour congestion pricing, and
commuter travel demand management (TDM) strategies that encourage use of
alternative travel modes, and major transit improvements.
Effective traf
fl
c demand reduction strategies (e.g., congestion pricing) require
those travelers who are unwilling/unable to pay the congestion charge to change
their travel behavior (e.g., mode, time, destination choice). Providing travel alter-
natives for drivers displaced by the congestion charge often requires substantial
investments to improve travel alternatives to the private car.
