Gantry cam flash

cyber69 · 25 Feb 2021 at 10:47

Got off the M69 onto M6 heading towards Brum last night and three lanes where closed shortly after so got behind a lorry in the outer lane (doing under the speed limit of 40) and gantry cam went off! Any idea if they where flashing the lorry? Do these gantry cams flash lorries who might be in the wrong lane?

I'm keeping the footage just in-case.

Footage

https://imgur.com/a/ih6ptvq

Yaayuh! · 25 Feb 2021 at 10:51

Best get the KY out boy.

cyber69 · 25 Feb 2021 at 11:00

Yaayuh! said:
Best get the KY out boy.

I've got the dashcam footage fortunately. I think it must have been flashing lorries in the outer lane as it went off near the end of the clip also to flash the lorry i'd overtaken when coming off the slip road onto the M6.

WJA96 · 25 Feb 2021 at 11:26

Certainly you're not in any danger - 29mph maximum.

tom_e · 25 Feb 2021 at 11:27

You'll find out in the next 14 days.

Quartz · 25 Feb 2021 at 11:28

I don't know if they've since solved it but perhaps 20 years ago there was a known issue where you could get flashed if there was a lorry nearby because the reflection off the side of the lorry screwed up the speed reading.

Was there a lorry to your rear left?

cyber69 · 25 Feb 2021 at 11:28

WJA96 said:
Certainly you're not in any danger - 29mph maximum.

On replay it looks like I was underneath the gantry at the time of the flash so it got the lorry in-front of me for some reason? I guess they won't prosecute the lorry driver for being in the outer lane as there was roadworks at the time? Can a gantry cam discern if a lorry is in the outer lane and zap him?

phil675 · 25 Feb 2021 at 11:51

Even if it flashed you in error, they can tell from the pictures if you were actually speeding or not.

cyber69 · 25 Feb 2021 at 12:02

I know these gantry cams can flash someone who is in a closed off lane but not sure if it can zap a lorry who is not supposed to be in the outer lane. Deffo did not zap me as it lit up the back of the lorry on the first and second flashes.

dlockers · 25 Feb 2021 at 13:08

What were your revs at?

cyber69 · 25 Feb 2021 at 13:32

dLockers said:
What were your revs at?

Err, low was following the lorry under 30mph

phil-k · 25 Feb 2021 at 14:05

I shouldn't worry, you were well under the speed limit and have got evidence

Semple · 25 Feb 2021 at 14:16

I didn't think they were intelligent enough to flash HGV / any vehicles that shouldn't be in the outside lane.

Perhaps the HGV was pushing over the speed limit?

There's a second flash towards the end of your clip as well, not sure if that's another gantry, or perhaps one on the other side of the road.

Edit: rewatched it again, it looks like the second flash was for behind you. Wonder if there was another HGV shortly behind you.

Scania · 25 Feb 2021 at 15:05

Happens often when pulling a tall trailer, that one looks pretty high, I’d guess around 15ft.

I’ve had the same when pulling tall trailers, never heard anything else about it mind you.

Wouldn’t stress about it.

Quartz · 25 Feb 2021 at 15:06

cyber69 said:
but not sure if it can zap a lorry who is not supposed to be in the outer lane.

The other lanes were closed.

Scania · 25 Feb 2021 at 15:12

Semple said:
I didn't think they were intelligent enough to flash HGV / any vehicles that shouldn't be in the outside lane.

Perhaps the HGV was pushing over the speed limit?

There's a second flash towards the end of your clip as well, not sure if that's another gantry, or perhaps one on the other side of the road.

Edit: rewatched it again, it looks like the second flash was for behind you. Wonder if there was another HGV shortly behind you.

The U.K. motorway network has “WIM” (weight in motion) sensors in the road surface which combined with an ANPR reader determines if the weight recorded matches the rated capacity of the passing HGV.

Fairly sure it won’t trigger a camera to flash but it will alert the motorway police who are quick to pull such overloaded vehicles, be it trucks or indeed vans.

https://trans.info/en/british-systems-catch-overloaded-trucks-see-how-they-work-108579

Scythe · 25 Feb 2021 at 16:38

It’s flashing due to the lorry being in lane 4 as mentioned above, it’ll get disregarded by the ticket office as the other three lanes were closed.

Diddums · 25 Feb 2021 at 18:46

Scania said:
The U.K. motorway network has “WIM” (weight in motion) sensors in the road surface which combined with an ANPR reader determines if the weight recorded matches the rated capacity of the passing HGV.

Fairly sure it won’t trigger a camera to flash but it will alert the motorway police who are quick to pull such overloaded vehicles, be it trucks or indeed vans.

https://trans.info/en/british-systems-catch-overloaded-trucks-see-how-they-work-108579

That's pretty damn impressive engineering wise tbh.

koooowweeee · 27 Feb 2021 at 07:30

dLockers said:
What were your revs at?

Lethal` · 28 Feb 2021 at 21:09

phil-k said:
I shouldn't worry, you were well under the speed limit and have got evidence

So when I get a speeding fine I can refute it with my own dashcam footage? Sounds likely.