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GATE 2021 CE (CE1) – Question 35

Traffic Engineering and Transportation Planning · Traffic signs, signal design by Webster method, intersections and interchanges · 1 mark · Numerical answer

A two-phase signal has lost time 3 s per phase and critical flow ratios 0.37 and 0.40. Find Webster optimum cycle in seconds, to one decimal.

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Correct answer: 60.7 to 61.1

Explanation

Total lost time is L=2×3=6 s and the sum of critical flow ratios is Y=0.77. Webster’s formula gives $C_0=(1.5L+5)/(1-Y)=14/0.23=60.8696$ s. **Answer: 60.9 s**.