Eli5: how do traffic ticketers know that your car has been in a spot on the street longer than the time limit?

Question

I park on the street in my city and there’s a 2 hour limit for cars without residential permits. How do they know you’ve been parked for longer than the 2 hr limit? Surely they don’t have surveillance on every street and don’t take note of every car’s whereabouts every 2 hours. Do they have some type of device that can tell how long a car has been still?

In: Other

Answer 1

I don’t know in the US but in Italy you have to signal the time you parked the car with something (can be a simple piece of paper on top of the dashboard) some cars has this [disc](http://it.wikipedia.org/wiki/Disco_orario#/media/File:Modello_disco_orario_italiano.svg) attached on the inside of the front windshield