Re: Deja vu
Some years ago when I was using public transport (trains) for my commute from east Kent to the Medway towns, there would be the occasional time when the train pulled into a station and the doors would not open for quite a while.
It turned out that the train onboard GPS had to agree that the train really was in a station to let the driver open the doors as normal and if it had lost the signal (or position which is the same thing really) the driver had to manually override the system (yes we really are at a station) to open the doors.
The older trains on that route still use it - not sure if the newer ones still do (but it would not surprise me if they did).
Someone with a GPS jammer could cause havoc on that line.