Civil Engineering Reference
In-Depth Information
Fig. 9.6 Extra time to make
important trips. Source
Reference [
7
], David Schrank,
Bill Eisele, Tim Lomax, TTI
'
s
2012 urban mobility
report
—
powered by Inrix
traffic data, December 2012
9.4.3 Implications
Travelers and freight movers typically adjust their trip times to the prevailing
(expected) congestion at the time of their trip, and they tend to adjust their daily
schedules to the prevailing traf
c congestion as long as they can predict their arrival
times to a destination. The ability to know how the average travel time for a trip is
likely to vary over time is essential for planning a reliable arrival time. This can be
done by adding an appropriate time buffer in trip planning.
Figure
9.6
shows an example of how the components of total trip time can vary
by time of day from an average trip [
7
]. In this case motorists making important
trips during peak travel periods have to plan for a travel time about three times what
it would take to make the trip in light traf
c conditions.
References
1. Martin WA, McGuckin NA (1998) NCHRP report 365: travel estimation techniques for urban
planning. Transportation Research Board, Washington, DC
2. Kuzmyak JR et al (2003) Transit cooperative research program report 95, chapter 15, land use
and site design, traveler response to transportation system changes. Transportation Research
Board, Washington, DC
3. Cambridge Systematics, Inc. with Texas A&M Transportation Institute, University of
Washington, Dowling Associates, Street Smarts, Herb Levinson, Hesham Rakha (2013) SHRP
2 Report S2-L03-RR-1, analytical procedures for determining the impacts of reliability
mitigation strategies. Washington DC
4. Cambridge Systematics, Inc., Dowling Associates, Inc., System Metrics Group, Inc., Texas
Transportation Institute (2008) NCHRP Report 618: Cost-effective performance measures for
travel time delay,variation, and reliability. Transportation Research Board, Washington, DC
