Imagine that your are in your car, on a highway; you are in a mad rush hour, bumper-to-bumper, in a big city… you are going to work.
What do you see?
Do you see, in your mind, large trucks? Really large trucks? Cars of different sizes? Also, imagine having motorcycles zipping in and out as well. You are all on the same highway trying to get from point a to point b with valuable cargo (you, in your case).
The highway is over 100% utilized at that point in time — the rush hour. The flow of traffic is very slow.