The GATE Grind

GATE 2021 CE (CE1) – Question 45

Traffic Engineering and Transportation Planning · Fundamental relationships of traffic flow · 2 marks · Multiple choice

Traffic speed and density satisfy u=70−0.7k, with u in km/h and k in veh/km. At capacity, the average time headway is

  1. 0.5 s
  2. 1.0 s
  3. 1.6 s
  4. 2.1 s

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: (D) 2.1 s

Explanation

Flow is $q=uk=70k-0.7k^2$. Maximising gives k=50 veh/km and u=35 km/h, so capacity is 1750 veh/h. Mean time headway is $3600/1750=2.0571$ s, approximately **2.1 s (D)**.