[gruez]

>A more effective trap would be a "no entry" sign on a one-way street (or one side of a dual carriageway), positioned so the car can't see it before entering the street.

reminds me of rollercoaster tycoon where you could trap guests indefinitely by using that technique.

[dnautics]

you could make a "do not enter" sign with undertext saying "except non-self-driving cars".