Average free flow speed and the jam density observed on a road stretch are 60 km/h and 120 vehicles/km, respectively. For a linear speed-density relationship

Q. Average free flow speed and the jam density observed on a road stretch are 60 km/h and 120 vehicles/km, respectively. For a linear speed-density relationship, the maximum flow on the road stretch (in vehicles/h) is     

Solution:

The correct option is 1800
V_f=60km/h
k_j=120veh/km

q_max=v_fk_j/4

=60*120/4

=1800