Fundamentals of Transportation/Shockwaves/Problem

Problem:

Flow on a road is q₁ = 1800veh / hr / lane, and the density of k₁ = 14.4veh / km / lane. To reduce speeding on a section of highway, a police cruiser decides to implement a rolling roadblock, and to travel in the left lane at the speed limit (v₂ = 88km / hr) for 10 km. No one dares pass. After the police cruiser joins, the platoon density increases to 20 veh/km/lane and flow drops. How many vehicles (per lane) will be in the platoon when the police car leaves the highway?

• Solution