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 Capacity and LOS: Example Problems

 
Peak Hour Factor

The results of a traffic count taken between 5:00 p.m. and 6:00 p.m. are given below:

Time Interval

Volume (vehicles)

5:00-5:15 p.m.
5:15-5:30 p.m.
5:30-5:45 p.m.
5:45-6:00 p.m.

900
1000
1200
850

5:00-6:00 p.m.

3950 total vehicles

The peak hour factor needs to be determined for this section of freeway.

[Solution shown below]

 

 

 

 

 

 

 

 

 

 

 

Solution

The equation for calculating the peak hour factor for 15-minute periods is as follows:

PHF=V/(4*V15)

where
V = peak-hour volume (vph) - 3950
V15 = volume during the peak 15 minutes of flow (veh/15 minutes) – 1200

Therefore,        PHF = 3950/(4 x 1200) = 0.82