Traffic flow on a three-lane (one direction) freeway can be described by the Greenshields model. One lane of the three lanes on a section of this freeway will have to be closed to undertake an emergency bridge repair that is expected to take 2 hours. It is estimated that the capacity at the work zone will be reduced by 30% of that of the section just upstream stream of the work zone. The mean free flow speed of the highway is 55 mph and the jam density is 135 veh/mi/ln. If it is estimated that the demand flow on the highway during the emergency repairs is 90% of the capacity, using the deterministic approach, determine: (i) The maximum queue length that will be formed (ii) The total delay (iii) The number of vehicles that will be affected by the incident (iv) The average individual delay

Question

What will be an ideal response?

Answer 1

(i)

uf = 55 mph, and kj = 135 veh/mi/ln

Traffic flow can be described by the Greenshields model, therefore, the capacity

of this freeway is





(iii)

The number of vehicles affected by the work zone

= v x t = 5012 x 2 = 10024 vehicles

(iv)

The average individual delay = dT / n = 6674 / 10024 = 0.6658 hours ? 49 min.