A toll plaza is capable of serving cars at a constant rate of μ cars/hr. Cars arrive at a constant rate 휆휆1<μ until some time 푡푡=0 (e. g. 7:00 am), but from 푡푡=0 until some time 휏휏, they arrive at a rate 휆휆2>μ (where 휆휆1 and 휆휆2 are in units of cars/hr). After time 휏휏, the arrival rate returns to the value 휆휆1 and remains there until time 휏휏′ (e. g. 7:00 am the next day) when the pattern repeats itself. Vehicles note served immediately form a queue and are served first-in, first-out. The queue present at time휏휏 vanishes by time 휏휏′.