Calculate the critical volume then estimate the green time interval for each pha
ID: 1845250 • Letter: C
Question
Calculate the critical volume then estimate the green time interval for each phase of the intersection using the data provided below. Assume that the intersection will operate as a simple two phase cycle with a 120 second cycle length. Please also assume 4 lanes per intersection approach (2 lanes in each direction).
Yellow + all-red is 5.0 seconds /
phase Northbound peak hour volume is 560 vph
Southbound peak hour volume is 750 vph
Westbound peak hour volume is 760 vph
Eastbound peak hour volume is 960 vph
Explanation / Answer
total effective green time of cycle(Tg)=cycle time -(yellow +all red time)=120-5=115 sec
critical lane volume for phase 1(VC1)=750vph
critical lane volume for phase 2(VC2)=960 vph
effective green time for first phase=VC1/(VC1+VC2) XTg=115x(750/1710)=50.43sec
effective green time for second phase=VC2/(VC1+VC2)XTg=115x(960/1710)=64.56sec
actual green time for first phase=50.43sec-5sec=45.43sec
actual green time for second phase=59.56sec-5sec=59.56sec