Civil Engineering - GATE Exam Questions - Discussion

8. 

A linear relationship is observed between speed and density on a certain section of a highway. The free flow speed is observed to be 80 km per hour and the jam density is estimated as 100 vehicles per km length. Based on the above relationship, the maximum flow expected on this section and the speed at the maximum flow will respectively be

[A]. 8000 vehicles per hour and 80 km per hour
[B]. 8000 vehicles per hour and 25 km per hour
[C]. 2000 vehicles per hour and 80 km per hour
[D]. 2000 vehicles per hour and 40 km per hour

Answer: Option D

Explanation:

No answer description available for this question.

Deepak Prajapati said: (Feb 6, 2015)  
Maximum flow = (free flow*jam density)/4.

(80*100)/4 = 2000 vehicles per hour.

Speed = Free flow speed / 2.

80/2 = 40 Km/h.

Chhaya said: (Jul 7, 2017)  
Thanks @Deepak.

Rocker said: (Jul 29, 2018)  
Why it is divide by 4 here?

Shivaprasad Sajjan said: (Feb 20, 2019)  
Jam density (K_j).
Free flow speed (uf).

Therefore, max flow is given by = 1/4 * Kj * if.
=1/4 * 80 * 100.
= 2000veh/hr.
Speed = 80/2 = 40kmph.

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