I think there was an idiom to describe 'lots of people', and the expression was related to truck... like tons of truck? or loaded by truck? I can't remember what it was. Does anybody know? If there is no such thing, is there any idiom to describe lots of people that will make a long line or that will fill all the big trucks?
You're probably thinking of the word truckload:
3 : a large amount - truckloads of money
It's used in far more situations than to describe people, but "a truckload of people" is an acceptable usage.