How does stacked parking work in NYC?

Question

Everytime I go to NYC, I noticed large steel-frame structures in parking lots to hold cars. How do the cars get up there? I feel naive for asking this, but I really don't know! Also, in front of the structure, there are about two rows of cars! How do the cars behind leave the parking lot if there are rows of cars in front of them? There is not way to get out of the parking lot, unless all the cars in front moved first.

Answer 1

it's a hydraulic lift, similar to what some service stations have.  Lot operators will ask you how long you intend to be there, or else they know you, and the cars coming out last go up on the rails.  At least that's the plan.  If someone needs the car from the lift early they have to shuffle all those others around.