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GATE 2016 CE (CE2) – Question 63

Traffic Engineering and Transportation Planning · Traffic signs, signal design by Webster method, intersections and interchanges · 2 marks · Multiple choice

The critical flow ratios for a three-phase signal are found to be 0.30, 0.25, and 0.25. The total time lost in the cycle is 10 s. Pedestrian crossings at this junction are not significant. The respective Green times (expressed in seconds and rounded off to the nearest integer) for the three phases are

  1. 34, 28, and 28
  2. 40, 25, and 25
  3. 40, 30, and 30
  4. 50, 25, and 25

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Correct answer: (A) 34, 28, and 28

Explanation

Critical ratio sum is Y=0.30+0.25+0.25=0.80. Optimum cycle C=(1.5L+5)/(1−Y)=(15+5)/0.20=100s. Available effective green is C−L=90s, distributed in ratio0.30:0.25:0.25. Values33.75,28.125,28.125s round to **34,28,28s, A**.