Question

The phase plan is given. Please answer:

a. The number of phases for the ring diagram.

b. Is this leading green phase or lagging green phase?

c. If total lost time of each phase is 2 s, what is the total lost time per cycle?

d. What is the sum of critical lane volume?

e. If the total effective green time is 80s, please allocate the effective green time to each phase.

ΦΑ 120 200 J. A1 or DA2 ΦΒ Vasco 650 310 7 IC ФС 80 210 AC1 or 6C2 348 270 AD (a) Intersection Layout (b) Ring Diagram

Answer 1

Based on the information given we have

a) Number of phases for this ring diagram = 6. We can break down these phases as follows. We have the following movements happening in each phase

АУ п Ph A Ph A1-A2 Ph B Ph C Ph C1-C2 PhD

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b) Lost time per phase = 2 seconds,

So total lost time = 2* 6 = 12 seconds

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c) For critical lane volumes, lets set up a table

Critical intersection volume is the highest number of vehicles that can be accomodated at the intersection based on the phase sequence and demand on each segment.

The sum of critical lane volume will be 1250 as shown below

In Phase A, green time equivalent to 120 vehicles will be given

In Phase A1-A2, the remaining 80 vehicles of SBL and 340 vehicles (out of the 650 through) will get green

in Phase B, 310 vehicles of NBT/R and 310 vehicles of SBT/R will get green. So we have the following.

Actual Flow (in vehicles) Flow to be considered in Calculations Critical Phase volume Phase A 120 Phase A1-A2 340 Phase B NBL SBL SBL SBT/R SBT/R NBT/R EBL WBL WBL WBT/R WBT/R EBT 310 120 200 200 650 650 310 80 210 210 348 348 270 120 120 80 340 310 310 80 80 130 Phase C 80 Phase C1-C2 130 78 Phase D 270 270 270 1250

d) Now to get effective green time for each phase, just divide the critical phase volume by the sum of critical volumes and multiply by total effectiv green.

So effective green for Phase 1 = 120/1250 *80 = 7.68 sec

Effective green for Phase 2 = 340/1250 * 80 = 21.76 sec

Actual Flow (in vehicles) Flow to be considered in Calculations Critical Phase volume Eff. Green time Phase A 120 7.68 Phase A1-A2 340 21.76 Phase B 310 19.84 NBL SBL SBL SBT/R SBT/R NBT/R EBL WBL WBL WBT/R WBT/R EBT 120 200 200 650 650 310 80 210 210 348 348 270 120 120 80 340 310 310 80 80 130 78 270 270 Phase C 80 5.12 Phase C1-C2 130 8.32 Phase D 270 17.28 1250 80.00

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