GATE CE 2021 Set 1 — Question 45
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Transportation Engineering → Traffic Studies & Flow → Speed-Density-Flow
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Question
On a road, the speed – density relationship of a traffic stream is given by (where speed, , is in km/h and density, , is in veh/km). At the capacity condition, the average time headway will be
Correct answer
(D) 2.1 s
Solution
Given the speed-density relationship:
This follows the Greenshields model:
Comparing the two:
Free-flow speed, km/h
Jam density, veh/kmCapacity (maximum flow), veh/hAverage time headway at capacity, s
Rounding to one decimal place, we get 2.1 s.
This follows the Greenshields model:
Comparing the two:
Free-flow speed, km/h
Jam density, veh/kmCapacity (maximum flow), veh/hAverage time headway at capacity, s
Rounding to one decimal place, we get 2.1 s.
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