Question

1 Consider saturation headway knowledge and the data in the table below (Heavy vehicles are denoted by an H). 

 A. What is the saturation headway from the data in the table?

 B. What is the corresponding saturation flow rate for the data in the table?

 C. What is the ideal saturation flow rate?

 D. What is the average start-up lost time per phase?

 E. If the approach has 34.5 seconds of effective green time from a 60 second cycle what is an estimate of the approach capacity?

2 Consider a two-phase intersection with a 75 second cycle length and the start-up and clearance lost times per phase listed below. a) How much time is actually available to move vehicles in a 1-hour period? and b) If the saturation headway is 2.2 seconds what is the maximum number of that vehicles can be accommodated per hour? c) repeat a & b assuming a 60 second cycle length d) discuss 

Answer 1

2)

A)

Step1: find effective time available for movement of vehicle per a cycle(g_i)

step2: find no of cycles in one hour=(3600/cycle time)

step3: total available time in hour for vehicle movement = (g_i *no of cycles)

D)If we compare the both the results fo 75sec cycle length and 60sec cycle length, when cycle is 60sec have more time losses. Actual time available for movement of vehice is very less and due to this lane can accommodate less no of vehicles per one hour.

Thank you