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GATE 2018 CE (CE1) – Question 25

Traffic Engineering and Transportation Planning · Fundamental relationships of traffic flow · 1 mark · Multiple choice

For the speed–density relation shown, the flow–density curve is ______.

Diagram for GATE 2018 CE (CE1) question 25
  1. piecewise linear
  2. parabolic
  3. initially linear, then parabolic
  4. initially parabolic, then linear

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Show answer and explanation

Correct answer: (C) initially linear, then parabolic

Explanation

Flow is $q=kv$. Initially speed is constant, so flow is linear in density. Beyond the breakpoint, speed decreases linearly with density, so multiplication by k makes flow quadratic. Thus initially linear then parabolic (C).