Solve for Unknowns:
Flow after police cruiser joins
Calculate the wave velocity:
Determine the growth rate of the platoon (relative speed)
Determine the time spent by the police cruiser on the highway
Calculate the Length of platoon (not a standing queue)
What is the rate at which the queue grows, in units of vehicles per hour?
The number of vehicles in platoon
How long will it take for the queue to dissipate?
(a) Where does the shockwave go after the police cruiser leaves? Just reverse everything?
Second wave never catches first.
(b) Return speed to 125, keep density @ 20?
Second wave instantaneously catches first
(c) Return speed to 125, keep density @ halfway between 14.4 and 20?
Second wave quickly catches first
(d) Drop upstream q,k to slow down formation curve.
Second wave eventually catches first
(e) If falls below downstream capacity, wave dissipates
Forward moving wave.