Blank sign on variable speed limit motorways

[johncrossley]

What is the speed limit following a blank sign on a variable speed motorway? (This includes most smart motorways, as well as the "controlled motorway" on the south west section of the M25).

Mostly you get a national speed limit sign following a previous restriction. That is presumably what is supposed to happen. But sometimes the signs suddenly go blank. Most motorists take this to mean that the speed limit is 70 mph and quickly accelerate as soon as they see a blank sign.

 

[Peter Mugridge]

What is the speed limit following a blank sign on a variable speed motorway? (This includes most smart motorways, as well as the "controlled motorway" on the south west section of the M25).

Mostly you get a national speed limit sign following a previous restriction. That is presumably what is supposed to happen. But sometimes the signs suddenly go blank. Most motorists take this to mean that the speed limit is 70 mph and quickly accelerate as soon as they see a blank sign.

If the signs go blank you should assume they are faulty and not displaying anything.

You should wait for a confirmed resumption of the national limit.

In practice, however, if you get more than one blank sign in a row I'd suspect the chances are they did switch the limit back without displaying the fact.

 

[bramling]

If the signs go blank you should assume they are faulty and not displaying anything.

You should wait for a confirmed resumption of the national limit.

In practice, however, if you get more than one blank sign in a row I'd suspect the chances are they did switch the limit back without displaying the fact.

This sort of thing isn’t really good enough, and it happens a lot. Doing a very slow speed for no reason on a motorway is potentially very dangerous, as is confusion about what the speed limit it. Another reason why smart motorways are a scourge which should be consigned to history. The system should be robust enough to work properly.

 

[Peter Mugridge]

This sort of thing isn’t really good enough, and it happens a lot. Doing a very slow speed for no reason on a motorway is potentially very dangerous, as is confusion about what the speed limit it. Another reason why smart motorways are a scourge which should be consigned to history. The system should be robust enough to work properly.

These signs - and their failure to be properly updated - aren't just on smart motorways; they're on normal motorways as well.

The agency has a reputation for failing to have the correct displays showing.

 

[pdq]

I'm pretty sure that, in the absence of any other regular indication, the National Speed Limit applies, so 70mph for cars or the appropriate speed for other vehicle types.

Hence why repeater 40 or 50 signs are necessary on unlit single carriageway roads.

 

[bramling]

These signs - and their failure to be properly updated - aren't just on smart motorways; they're on normal motorways as well.

The agency has a reputation for failing to have the correct displays showing.

Yes and that’s not good enough either. I have it on the A1M in the evening, where you get the matrix signs showing 40 mph, for overnight roadworks 4 miles ahead. Would be farcical if it wasn’t dangerous.

 

[Peter Mugridge]

Yes and that’s not good enough either. I have it on the A1M in the evening, where you get the matrix signs showing 40 mph, for overnight roadworks 4 miles ahead. Would be farcical if it wasn’t dangerous.

Fully agree.

Roads management in this country is very lacking.

 

[chipbury]

The speed cameras on the M4 gantries around Bristol are set at 70 if there is no reduced limit shown.

I had to to a speeding awareness course when I found out...

 

[splitfare]

If the sign is blank, then unless there are other signs to the left or right of the sign indicating otherwise, then the appropriate national speed limit applies. The situation you describe can arise when traffic conditions have improved and the length of the temporary speed limit is adjusted. The end point will have moved to behind you vehicle - the last sign you passed with a speed limit showing may now be showing the "national speed limit sign applies" symbol.

pdq wrote - "Hence why repeater 40 or 50 signs are necessary on unlit single carriageway roads".
Also (if not 30mph limit) repeaters are required on lit single and dual carriageway roads. A repeater is required for 30 if an unlit road but if lit (and not a motorway), it is 30 unless otherwise signed {and repeated).

 

[D365]

Agree with the comments about the confusing/dangerous blank speed signs. Usually ends up with trucks speeding forwards and backwards.

 

[Bletchleyite]

This sort of thing isn’t really good enough, and it happens a lot. Doing a very slow speed for no reason on a motorway is potentially very dangerous, as is confusion about what the speed limit it. Another reason why smart motorways are a scourge which should be consigned to history. The system should be robust enough to work properly.

I have come across this too. The cameras include in the picture a fibre optic picture of what is actually being shown on the above lane version (not sure about the at the side version) so you shouldn't get done for a blank gantry.

In my view though they should all show the NSL sign if NSL applies. If the old matrix "computer zero" version was used added electricity use would be low.

== Doublepost prevention - post automatically merged: 9 May 2023 ==

These signs - and their failure to be properly updated - aren't just on smart motorways; they're on normal motorways as well.

The agency has a reputation for failing to have the correct displays showing.

The ones on normal motorways have no legal force and most motorists ignore them bar considering them a warning of possible issues ahead.

 

[jon0844]

To clarify, you're referring to the older matrix signs without a red circle. I think Peter was referring to a variable speed limit section which doesn't have to also be a smart motorway.

Basically, a red border means it is legally enforceable.

I'm sure that's what you meant of course, but just in case not everyone knows.

 

[tomuk]

I have come across this too. The cameras include in the picture a fibre optic picture of what is actually being shown on the above lane version (not sure about the at the side version) so you shouldn't get done for a blank gantry.

If you look to the left prior to the gantry there is a usually a number of small cameras pointing at the gantry signs to verify they are operating correctly.

In my view though they should all show the NSL sign if NSL applies. If the old matrix "computer zero" version was used added electricity use would be low.

They did run a trial on the M1 around Chesterfield where they left the signs on showing a NSL sign.

 

[Peter Mugridge]

To clarify, you're referring to the older matrix signs without a red circle. I think Peter was referring to a variable speed limit section which doesn't have to also be a smart motorway.

Basically, a red border means it is legally enforceable.

I'm sure that's what you meant of course, but just in case not everyone knows.

That is right - I specifically had in mind the M25 variable limit when I wrote that post; there have been numerous complaints of blank / expired details on this. The M25 also has speed cameras on every gantry which are automatically adjusted to match whatever limit is being displayed on that gantry.

That makes it essential in more ways than one to know how to treat a blank sign.

 

[jon0844]

Years ago I was told that when a speed limit sign comes on, there's a delay before the cameras are activated - or indeed, the camera on the first one to come on may not activate at all (indeed some gantries don't have cameras). I think the same applies if a speed limit is reduced, giving a grace period.

When the speed limit is lifted/removed, it would make sense to show the national speed limit sign for a period of time on all gantries before going blank - ensuring people will see at least one and no longer feel they have to drive at 40mph until the next speed limit sign, which could be many miles.

 

[Bletchleyite]

There is indeed a grace period to avoid doing people where it changes when they are already under it. However I suspect it is fairly short.

 

[jfollows]

There is indeed a grace period to avoid doing people where it changes when they are already under it. However I suspect it is fairly short.

It has to be more than 10 seconds but is probably more like 60 seconds (according to Highways England in a Freedom of Information response); see https://www.railforums.co.uk/threads/speeding-fine.246167/page-4#post-6157084

 

[Ted633]

That is right - I specifically had in mind the M25 variable limit when I wrote that post; there have been numerous complaints of blank / expired details on this. The M25 also has speed cameras on every gantry which are automatically adjusted to match whatever limit is being displayed on that gantry.

That makes it essential in more ways than one to know how to treat a blank sign.

M25 speed cameras. Definitely on the stretch I drive regularly (J7 - 14), there are not speed cameras on every gantry. In fact, there are only 2 in either direction along that entire stretch. They are the yellow ones mounted on the side of the gantries, which are clearly visible. These also adjust for the speed displayed on the gantry, and will also trigger if someone goes through a red X. If you look, there is a camera pointing at the gantry a couple hundred yards beforehand, presumably to prove what the gantry was displaying at the time of an offence.
You do see something mounted above each lane behind some of the gantries and I think these may of used to be speed cameras, however they have long since been deactivated.

 

[tomuk]

M25 speed cameras. Definitely on the stretch I drive regularly (J7 - 14), there are not speed cameras on every gantry. In fact, there are only 2 in either direction along that entire stretch. They are the yellow ones mounted on the side of the gantries, which are clearly visible. These also adjust for the speed displayed on the gantry, and will also trigger if someone goes through a red X. If you look, there is a camera pointing at the gantry a couple hundred yards beforehand, presumably to prove what the gantry was displaying at the time of an offence.
You do see something mounted above each lane behind some of the gantries and I think these may of used to be speed cameras, however they have long since been deactivated.

The current cameras are HADECS3 mounted to the side of some of the gantries as described above. The older system originally installed were a GATSO style camera one mounted above each lane in the gantry behind the dot matrix speed indicator these have been phased out and most if not all removed.

 

[Bletchleyite]

The current cameras are HADECS3 mounted to the side of some of the gantries as described above. The older system originally installed were a GATSO style camera one mounted above each lane in the gantry behind the dot matrix speed indicator these have been phased out and most if not all removed.

I seem to recall the original GATSOs had a fibre optic feed from the display above it, so they knew what it was actually showing rather than what it was meant to be.

 

[Bald Rick]

The M25 also has speed cameras on every gantry which are automatically adjusted to match whatever limit is being displayed on that gantry.

They are not on every gantry, far from it. But they do adjust to the speed displayed.

There is indeed a grace period to avoid doing people where it changes when they are already under it. However I suspect it is fairly short.

Minimum 60 seconds.

 

[MotCO]

That is right - I specifically had in mind the M25 variable limit when I wrote that post; there have been numerous complaints of blank / expired details on this. The M25 also has speed cameras on every gantry which are automatically adjusted to match whatever limit is being displayed on that gantry.

That makes it essential in more ways than one to know how to treat a blank sign.

Indeed - a blank screen may mean NSL, or it may mean the screen isn't working. Displaying the speed limit on every screen would overcome the latter point.

 

[tomuk]

Indeed - a blank screen may mean NSL, or it may mean the screen isn't working. Displaying the speed limit on every screen would overcome the latter point.

If the whole gantry was blank due to a fault your aren't going to get a ticket and it won't need the trick lawyer to get you off.

As I posted before on the Chesterfield stretch of the M1 the *Highways Agency* did trial showing NSL on the signs. I don't know the outcome of said trial.

 

[jon0844]

Seems odd to need to trial it, unless a major factor was the cost of illuminating said signs.. but given how much of the motorway network still hasn't installed LED lighting I am not sure that's a factor.

I imagine these days you can now get very bright, full-colour, displays that cost a fraction of what these did - and are significantly thinner and lighter such that they won't need such crazy big gantries that look like they'd be able to take the weight of a small shopping centre above them (I may have exaggerated slightly here).

 

[P Binnersley]

The Legislation for M42 Junction 7 to 9 (Variable speed limits) states (I presume other orders are similar):

Variable speed limits​

3.—(1) No person shall drive a vehicle on a section of a road which is subject to a variable speed limit at a speed exceeding that indicated by a speed limit sign.

(2) A section of a road is subject to a variable speed limit in relation to a vehicle being driven along it if—

(a)the road is specified in the Schedule;

(b)the vehicle has passed a speed limit sign; and

(c)the vehicle has not passed—

(i)another speed limit sign indicating a different speed limit; or

(ii)a traffic sign which indicates that the national speed limit is in force.

(3) In relation to a vehicle, the speed limit indicated to a vehicle by a speed limit sign is the speed shown at the time the vehicle passes the sign, or, if higher, the speed limit shown by the sign ten seconds before the vehicle passed the sign.

(4) For the purpose of this regulation a speed limit sign is to be taken as not indicating any speed limit if, ten seconds before the vehicle passed it, the sign had indicated no speed limit or that the national speed limit was in force.

So
i) The speed restriction applies until you pass either a different speed limit or a Nation Speed Limit sign.
ii) The legal minimum is 10 seconds after the sign changes. In practice I expect a longer period would be used as the camera is after the sign and to avoid any legal challenges.

 

[tomuk]

The Legislation for M42 Junction 7 to 9 (Variable speed limits) states (I presume other orders are similar):



So
i) The speed restriction applies until you pass either a different speed limit or a Nation Speed Limit sign.
ii) The legal minimum is 10 seconds after the sign changes. In practice I expect a longer period would be used as the camera is after the sign and to avoid any legal challenges.

You would travel over a quarter of a km at 60mph

 

[Bryan rich]

Good evening, found these recent posts interesting. Could anyone confirm if the absence of a NSL, or 'END' sign, after a variable limit on a motorway, been challenged in court?

 

[tomuk]

Good evening, found these recent posts interesting. Could anyone confirm if the absence of a NSL, or 'END' sign, after a variable limit on a motorway, been challenged in court?

Why would it be challenged in court? All the regulations have the following or very similar clause

For the purposes of this regulation a speed limit sign is to be taken as not indicating any speed limit if, ten seconds before the vehicle passed it, the sign had indicated no speed limit

 

[johncrossley]

Why would it be challenged in court? All the regulations have the following or very similar clause

But if the sign "indicated no speed limit", is that the same as that sign not being there? If so, then the previous sign displaying a speed limit or the national speed limit would be in force. I presume you are assuming that it means that the national speed limit applies, but the wording is ambiguous.

 

[jfollows]

In general, with this latest type of motorway variable speed limit, the advice of intended prosecution normally supplies a pair of pictures - one of the vehicle and one of the displayed speed limit. In any case, the latter would be required as evidence in a prosecution. So I would assume that a blank display is unenforceable and wouldn't be used to attempt a prosecution.