So i was driving today to Lucerne and was on a motorway where the limit was 100kmh. It was a path with a long left turn, and 2 cars in front of me were flashed, and then when I approached - was flashed as well. It's a fixed camera.
Question: was it a random flash? just confused. the whole motorway was doing 100 and nobody slowed or sped up...
If that truly was your real speed and the limit was 100 then you have nothing to worry about. The same has happened to me (not in CH though) and I didn't even get a letter.
Possible reasons for random flashing are: mobile phone control, seatbelt control, and camera testing/calibration. It's still annoying as hell though. When that happened to me it was dark and I was blinded for a second.
Double flash used to be the norm. It gave a way to confirm that the radar was correctly calibrated if there were some object of known length on the road surface.
As far as I know the cameras will only take a photo of the front of the car. I have been in a car twice while getting blitzed in Switzerland. The first time it was dark and a red flash went off twice in the front. On the second time it was daytime and a (white) flash went off once (on the autobahn near Luzern where they love those blitzers ).
It's possible that the second flash was for the car in front of you. How far were you from the camera?
2-3 sec is a pretty large interval for highway speeds. The only explanation for an interval that large which I can think of is to eliminate the car ahead of you claiming that he was being tailgated.
1/4 or 1/2 sec would seem more like the double flash interval for highway speeds.
On two separate occasions I've been flashed in Zurich.
Two lanes each way and plenty of traffic round me all going about 50 in a 50 limit. Some closing the gap and going a bit faster to catch up the car in front. Some lane changing going on.
Two flashes - never heard anything more. Probably confused he cameras. Newish laser ones...
At the worst case scenario where you've been flashed doing 97 in a 80 zone (maybe it was temporary and you didn't see the sign), the fine isn't going to be huge (100-ish francs) an there won't be any extra proceedings, just a bog standard fine through the post.
You could try to challenge it but it rarely works out and the cheapest option is just to grit your teeth and pay up.
As I said, that's the worst case scenario so I wouldn't sweat it.