Question

2. A freeway is being designed for a location in rolling terrain. The expected free-flow speed is 55 mph. During the peak hour, it is expected there will be a directional peak-hour volume of 2700 vehicles and 18% heavy vehicles. The PHF is expected to be 0.88. If a LOS no worse than D is desired, determine the necessary number of lanes.

Answer 1

Number of necessary lanes = 3

Step-by-step explanation:

Expected free flow speed = 55 mph

Volume of vehicles expected during peak-hour = 2700

PHF = 0.88

18% = 0.18 for heavy vehicles ( Pt )

Et ( for a rolling terrain ) = 3

Detailed solution attached below

First we calculate the Heavy-vehicle adjustment factor before determining the number of lanes