Civil Engineering Reference
In-Depth Information
Fig. 8.4
Percent of delay by
time of day.
Source
Reference
[
15
], p 7. Exhibit 5
Fig. 8.5
Percent of delay by
road type.
Source
Reference
[
15
], p 7. Exhibit 6
(Fig.
8.5
). It should be noted that the UMR [
9
]de
nes delay as the difference
between an actual travel time rate and the travel time rate for free
fl
flow conditions.
8.3 Congestion Thresholds Re
fl
ecting Travelers
Expectations
The thresholds for tolerable congestion levels should re
fl
ect traveler and freight
movers
inputs, and can be set by policy committees of public agencies for each
type of roadway and surrounding environment.
'
8.3.1 The National Committee on Urban Transportation
In 1958, the National Committee on Urban Transportation [
16
],
first issued peak
and off-peak hour standards for
for expressways/
freeways, major arterials, collector and local streets. These standards are shown in
Table
8.5
.
“
minimum desirable delays
”
