D$/$D$/1$ QUEUING

Vehicles arrive at an entrance to a recreational park. There is a single gate $($at which all vehicles must stop$),$ where a park attendant distributes a brochure. The park opens at $8$:$00$ am at which time vehicles begin to arrive at a rate of $480ve\frac{h}{h}r.$ After $20$ minutes the arrival flow rate declines to $120ve\frac{h}{h}r,$ and it continues at that level for the remainder of the day. If the time required to distribute the brochure is $15$ seconds, and assuming $\frac{D}{D}\frac{?}{1}$ queuing, describe the operational characteristics of the queue $-$ maximum queue length, maximum waiting time, and total delay