That's assuming an 18-second dispatch (from Touring Plans) which to me doesn't seem right.
But checking my math using that data:
There are 3600 seconds in an hour. Divided by 18 seconds gives 200 dispatches per hour. Times 32 passengers per truck is 6400 per hour.
Even if we halve that to one truck dispatch every 36 seconds, that's a theoretical capacity of 3200/hour. Operationally I hesitate to think that's even possible... The second truck in a pair is probably 20-30 seconds behind the first truck, but you don't get a pair of trucks departing the loading dock every 72 seconds, do you?
-Rob