Civil Engineering Reference
In-Depth Information
Trip Purpose
Being late to a job interview is likely to be viewed as more costly than being late to
a dinner party.
Amount of Delay
The cost of a 1 min delay may be less than 1/30 the cost of a 30 min delay.
Trip Length
The cost of a 5 min delay for a 30 miles trip is not the same as the cost of 10 min
delay for trips of one mile.
Traveler Income
The unit cost of delay is higher for a high-income traveler than for a low-income
traveler.
Travel Conditions
The perceived cost of a pre-announced 15 min delay on a section of congested road
is not the same as the cost of the same 15 min delay experienced on a road
providing no travel time delay information to drivers.
A trip delay of 15 min on a sweltering summer day in a vehicle with a mal-
functioning air conditioner, is more onerous than if driving a vehicle with func-
tioning climate control.
Conclusion
Travel time values are to be perceived differently by different road users according to
their particular needs, travel conditions of their trip, duration of delay, and if delay
information is known or unknown to travelers. These conditions should be recog-
nized in developing time costs for assessing the bene
ts if congestion relief programs.
13.2.1.3 Fuel Consumption and Traf
c Congestion
The Fuel Economy Guide [
22
] published by US Department of Energy lists the
following factors that can lower a vehicle
'
s fuel consumption:
Aggressive driving (speeding and rapid acceleration and braking) can lower gas
mileage by as much as 33 % at highway speeds and 5 % around town.
Excessive idling, accelerating, and braking in stop-and-go traf
c;
Cold weather (engines are more efficient when warmed up);
Driving with a heavy load or with the air conditioner running;
Improperly tuned engine or underin
fl
ated tires; Use of remote starters.
Many short trips taken from a cold start can use twice as much fuel as one
multipurpose trip covering the same distance. And let the car idle to warm up
doesn
it help with the fuel economy: it actually uses more fuel and creates more
pollution.
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