Motorway, variable and temporary speed cameras

sevenhills

It has puzzled me for quite some time. How are the above speed limits proved in court?
With standard speed limits, it there is a speed camera, you then look for the speed limit sign to confirm what the speed limit is.
But if you get a letter in the post, that you have broken a variable speed limit, you cannot go and see the road sign.
The sign above the motorway may be 60mph, but how do the courts prove it it was lit when you passed it?

Frudd

Interesting point. There might be a monitoring camera set up so that the gantry is being filmed at the same time. So they can show the footage of the gantry with said speed limit and the pic of the speeding car.

TonyMMM

sevenhills wrote: »

It has puzzled me for quite some time. How are the above speed limits proved in court?
With standard speed limits, it there is a speed camera, you then look for the speed limit sign to confirm what the speed limit is.
But if you get a letter in the post, that you have broken a variable speed limit, you cannot go and see the road sign.
The sign above the motorway may be 60mph, but how do the courts prove it it was lit when you passed it?

A system log will be produced from the computer that controls the signs and cameras showing that a certain limit was being displayed on a particular gantry at the time you were captured.

The most modern (Hadecs 3) system takes a photo showing the gantry and the vehicle as it passes to avoid any doubt.

robatwork

I have had a similar thought in passing - for example I was driving on the M25 past the M4 this weekend, going at 70 as the gantry came to life as I approached; as I went underneath it I was slowing safely but was definitely going above the 50 it had just changed to.

I'd hope the system takes that into account and doesn't trigger the cameras until say 20 seconds after the limit is enabled.

z1a

robatwork wrote: »

I have had a similar thought in passing - for example I was driving on the M25 past the M4 this weekend, going at 70 as the gantry came to life as I approached; as I went underneath it I was slowing safely but was definitely going above the 50 it had just changed to.

I'd hope the system takes that into account and doesn't trigger the cameras until say 20 seconds after the limit is enabled.

I think there's a 10 second delay, but not 100% sure.

daveyjp

60 seconds.

Nearly_Old

At all gantries fitted with HADECS3 cameras on the nearside gantry leg there is an additional camera mounted on the verge in advance of the gantry. When a vehicle exceeding the limit (either NSL or any lower displayed limit) is detected both cameras take an image. The evidence consists of the two images - one showing the vehicle with the other showing the signs on the gantry.

migger02

z1a wrote: »

I think there's a 10 second delay, but not 100% sure.

Imo 10 second delay is not enough, should be at least 20 secs.

Car_54

migger02 wrote: »

Imo 10 second delay is not enough, should be at least 20 secs.

And your opinion is based upon what?

robatwork

Nearly_Old wrote: »

At all gantries fitted with HADECS3 cameras on the nearside gantry leg there is an additional camera mounted on the verge in advance of the gantry. When a vehicle exceeding the limit (either NSL or any lower displayed limit) is detected both cameras take an image. The evidence consists of the two images - one showing the vehicle with the other showing the signs on the gantry.

That's interesting, but as they are stills it doesn't allow for the warning signs just illuminating. Would be better to have a 5 second video clip.

Nearly_Old

robatwork wrote: »

That's interesting, but as they are stills it doesn't allow for the warning signs just illuminating. Would be better to have a 5 second video clip.

There is very good guide from the South Yorkshire Camera Partnership - http://www.safetycamera.org/smart-motorways/faq


This confirms that the standard delay after a change in the indicated speed limit is one minute. As far as I know there has always been a one minute delay as it had been built into the system. In view of this period of grace then the 2 still photographs are adequate as traffic can easily "clear" a gantry detection zone in the one minute delay period when there is no enforcement; e.g. speed change from 60 to 50; a vehicle travelling at 60mph passing under the gantry 30 seconds after the change would be 1/2 a mile past the gantry by the time enforcement starts. Of course this ignores the fact that the vehicle was 1/2 mile away from the gantry when the change was made so should have had time to slow down before the gantry.