A signalized intersection approach has three lanes with no exclusive left or right turning lanes. The approach has a 40-second green out of a 75-second cycle. The yellow plus all-red intervals for phase total 4.0 seconds. If the start-up lost time is 2.3s/phase, the clearance lost time is 1.1s/phase, and thesaturation headway is 2.48 s/veh under prevailing conditions, what is the capacity of the intersection approach?

786.01

Explanation:

Calculate the saturation flow rate by using the following equation

S = 3600/h, where h is the saturation headway

S = 3600/2.48 = 1452 veh/hg

Calculate the effective green time

G (i) = G (i) + Y (i) - t (Li), where G (i) is the actual green time for movement, Y (i) is the sum of yellow and all red intervals for movement, and t (Li), is the total lost time for movement

G (i) = 40, Y (i) = 4, t (Li) = 2.3 + 1.1 = 3.4

G (i) = 40 + 4 - 3.4 = 40.6

Calculate the capacity of an intersection approach by using the following equation

C (i) = s (i) [g (i) / C], where s (i) the saturation flow rate, g (i) is the effective green time, and C is the cycle length

s (i) = 1452, g (i) = 40.6, C = 75

C (i) = 1452 x (40.6/75) = 786.01 veh/h/ln

The capacity of intersection approach is 786.01