Civil Engineering Reference
In-Depth Information
c congestion on trip time,
all segments of the trip (as shown in Table
10.4
) must be considered in the analysis.
Therefore, to accurately evaluate the impact of traf
Impact of Freeway Congestion on Trip Mobility
As shown in Fig.
10.4
, a traveler
s response to increased freeway congestion would
be either to reduce trip mobility by over 15 % (from 10 to 8.46 miles)
'
—
for a
constant trip time
or to increase trip time by 18 % (from 26.7 to 31.5 min) in order
to maintain the same level of trip mobility (10 miles).
Data on traveler responses to an increase in travel speed shows that travelers
generally have used the travel time reductions to increase the trip distance instead of
reducing their trip times [
10
]. So it may be inferred that the converse is true: when
congestion increases travel time, trips distance (mobility) would decrease.
—
Comments
The example uses 35 mph freeway speed to represent acceptable peak hour speed
conditions
—
a realistic assumption for many freeways in large metropolitan areas.
This value (35 mph) is considerably less than the freeway free-flow speed (e.g.,
Fig. 10.4 Congestion impacts on mobility and trip time for a trip 10 miles long
