Sub-problem 3a - Page 1 of 7 |
ID# C203A01 |
Sub-problem 3a: Shenendehowa Campus AM & PM peak - Existing Conditions
Peak
Hour Factor
The
peak hour factor (PHF) accounts for variations in flows that occur during
the heaviest hour of traffic. If the volume for the hour is 800 vehicles
and the heaviest volume duLevel of Serviceny one 15-minute period is 250 vehicles,
then the peak hour factor is 0.80 (800/(4*250)). When you input the hourly
volumes and the peak hour factor, you will evaluate the conditions that exist during the peak 15
minutes, the time when the facility is most heavily loaded.
We can use the highly peaked flows at
the entrance to the Shenendehowa campus to show how the peak hour factor
works and the effect it has. Using data for this intersection will show
how the typical method for applying the peak hour factor might or might not lead
to the right assessment of the performance conditions in some situations.
Discussion:
Traffic
engineers hold different perspectives on the peak hour factor. Some compute
values for each clock hour (3-4, 4-5, etc.). Some consider each sequence of
four 15-minute time periods and use the sequence with the maximum total
volume for the peak hour factor. Some predicate PHF
calculation on the sequence of 15-minute time periods that has the maximum
flow for the movement, others, the maximum total intersecting volume for
the intersection. Still others focus on demand, not volume as the basis
for computing the PHF. What do you do? What do you think should be done if
the data were available?
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Peak Hour Factor Analysis |