Speed camera question

Pooky23

I may have been completely mistaken for all the years I have been driving, but a speed camera flashed at me today when I was approaching it. The camera was located on the other side of the road, facing me, but it is one I am familiar with and I always thought it was set up to trap drivers driving in the the opposite direction (i.e those driving away from it, not towards it).

I cannot be sure whether I was going too fast or indeed whether it was me it was flashing at. A car had overtaken me at speed and a bus was coming in the opposite direction, potentially it could have been either of them but in the split second I registered it flashing, I couldn't take in the exact position of the other cars.

I have 3 (old) points for speeding and am dreading getting any more.

If anyone can explain how they are usually set up I would be grateful.

Ebe_Scrooge

Some cameras can detect cars from both directions. The give-away is normally the series of lines painted on the road - if they're only on the side of traffic driving away from the camera, then it will only register those cars, if there are markings on both sides of the road then it can detect both lines of traffic. If you've only got 3 points, and you weren't doing a silly speed, then I wouldn't worry too much - it'll be £60 and 3 more points. You'll have to notify your insurance company of the new points, but these days most insurance companies won't penalise you too heavily for 2 SP30 offences ( if your existing points are more than 5 years old, they won't count anyway as far as insurance is concerned ).

Lemonade_Pockets

I'm 99% sure its only GATSO's which flash and these only record people driving away not towards. The forward facing ones usually use infra red to take the photo's e.g. Truvelo. This means that the flash doesn't dazzle the driver. So i think in this situation it probably got the bus.

Ebe i thought if it had lines on both sides it was to catch people overtaking as well, e.g on a long straight to stop people just driving on the wrong side of the road to avoid the camera. I've never heard of a camera been calibrated to catch people driving in both directions. My mind boggles at how this would work if two cars travelling in opposite directions at 80mph crossed the markings at the same time.

I stand to be corrected of course as you learn something new everyday.

Ebe_Scrooge

OK, I'll start by saying that I'm not an expert on the technicalities :-) But my understanding is that the camera initially detects the speed by using radar / laser. It then takes 2 pictures a fraction of a second apart. The lines on the road are to double-check the results. If you know the distance between the lines, and the time difference between the two pictures, it's simple maths to work out the speed by counting the distance covered in a known time. So, if there are 2 cars in the pictures, then they can tell which one is speeding.

( Stands back and prepares to be flamed ! )

Lemonade_Pockets

I'm no expert either so won't get into a dispute on the technicallities of how they work especially as yours sounds convincing

However this might interest you - taken from this website http://www.speedcamerasuk.com/Gatso.htm
"It is common for fixed Gatsos to be positioned so they can be turned around to check both sides of the road - but only one direction at a time. "


Like i say i can't explain why but thats the way i always understood it as well and have presumed that its because its tricky to calibrate it for both directions.
I suspect because to do it in both directions there would have to be 2 pairs of trigger points but one would have to be the opposite to the other. :-S My heads hurting

Crabman

If it was a GATSO that flashed you head on you should be ok - as far as I know (see Dr Science's post here) they're only type approved by the Home Office for rear facing enforcement (i.e. vehicles travelling away from GATSO).

If however it was a Truvelo (you'd have seen a magenta/purple tinted flash instead of a white one) then that is designed and type approved to flash from the front. It's unlikely that would be on the other side of the road though.

Pooky23

Yes, it was a white flash, two in v quick succession. It's a camera that has been pointing in the same direction for years (it's not a recent addition) so I don't think they have altered it. It just gave me a bit of a fright. I'll wait for two weeks to see if a letter lands on my doormat! Thanks for all your help.

mattwallisuk

Had a car just gone past on the other side of the road?

To me it sounds like it was not measuring your side and was likely flashing the last person to go past it the other way...

tomstickland

Gatsos do flash sometimes when you approach them, but nothing will come of it.

Treadway1

It is possible with the old style gatso's to set them off as you approach them. Basically, the mechanism inside that detects a cars speed gets confused, and takes a picture as it believs someone has just hit the parameters required for it to take a picture. It can also happen if a luton type van (or any truck with a slide down back door) goes past at slow speed. The vibration from the back door, again confuses the camera and it goes off.

I would also bet that this happened during darkness hours aswell, as this is when the camera is most likely to be confused by oncoming cars with lights on. Its nothing to worry about, becuase even if there are marks on your side of the road, these cameras arent designed to take measurements with vehicles approaching it. Lastly, I had this happen to me a while ago, and nothing came of it.

Hope this helps.

LeeSouthEast

In the situation you describe, the camera has entered "deter" mode, which basically means it's run out of film and will flash anything going over the speed limit - approaching it or going away from it.