A section of an arterial road has been found to have a speed-density relationship that was modelled using the following form:

where v is the space-mean speed in kilometres per hour (km/h), and k is the density in vehicles per kilometres (veh/km).

The relationship was found to have the best fit to the data by using the following coefficients:

a = 3.5

k_m = 138 veh/km

Which option below best presents the critical density (ie the density at which the capacity is obtained) of the above arterial road?

A linear regression fit to real traffic data speed (v) and density (k) data has the following relationship: v= 110 –0.5*k, where v is measured in kilometres per hour (km/h) and k is measured in vehicles per kilometre (veh/km). Which option below best describes the maximum flow of this fundamental diagram, measured in vehicles per hour (veh/h)?

Regarding speed, flow, density relationships, which statement below is TRUE?