Question

A six-lane freeway (three lanes in each direction) currently operates at maximum LOS C conditions. The lanes are 11 ft wide, the right-side shoulder is 4 ft wide, and there are two ramps within three miles upstream of the segment midpoint and one ramp within three miles downstream of the segment midpoint. The highway is on rolling terrain with 10% heavy vehicles, and the peak hour factor is 0.90. Determine the hourly volume for these conditions.

Answer 1

Answer:

4.071 veh/h.

Explanation:

Step one: calculate the estimated free flow speed by using the formula below;

= 75.4 - F(L) - F(C) - 3.22T^ 0.84.

The value of F(L) = 1.9 m/h and F(C) = 0.8 m/h.

Hence,

free flow speed = 75.4 - 1.9 - 0.8 - 3.22(3/6)^0.84.

free flow speed= 75.4 - 1.9 - 0.8 - 1.799

free flow speed= 70.901 mi/h = 70 mi/h.

Step two: determine the adjustment factor by using the formula below;

The adjustment factor = 1/ [1 + Pm (Em - 1) + Pn (En - 1)].

The adjustment factor = 1/[ 1+ 10/100 ( 2.5 - 1) + 0(2.0 - 1] = 0.869.

Step three;

Calculate the hourly volume;

The value corresponding to the LOS C conditions and free flow speed at 70 mi/h is 1735.

Therefore,

hourly volume, V = 1735 × 0.9 × 0.869 × 3.

Hourly volume, V = 4.071 veh/h.