Overhead gantries on smart motorways

[BlindedByTheLights]

I know there’s a few highways and police on here so hopefully a factual answer will come from this.

I regularly travel on the so called smart motorway that is the m20. Every evening the gantries are lit up with reduced speed limits, usually 60 with a cheeky 50 on its own in the middle of two 60’s. So it often looks like this:

Gantry 1: 60mph
Gantry 2: 50mph
Gantry 3: 60mph
Gantry 4: blank
Gantry 5: national speed limit symbol.

So my question is, what is the speed limit through the blank gantry 4 as this IS fitted with cameras?

Nearly everyone on the m20 is staying at 60mph or whatever is displayed until they reach gantry 5, are they correct?

[119]

60

[BlindedByTheLights]

I am alright Jack said:

Technically 60, but you wont receive a ticket from the camera on the gantry with nothing displayed for driving at the nsl.

Technically based on what though? When all gantries are blank there are no NSL signs displayed anywhere so it is accepted as NSL.

[andyb28]

Last night, after a very long drive from the Alps, we got off the tunnel and hit the M20.

There was a very serious crash on it, so I can fully understand the controls in place for that. However, later on down the road there were multiple lots of speed changes for no apparent reason at all. One of them said there was a stranded car, slowed everyone down to 40 in the end. When we finally got to the stranded car, it was completely away from the motorway lanes in a kind of layby. The other two occurrences appeared to be for no reason at all.

We had just driven 600 miles across the amazing French toll roads without a single issue, only to have this on the M20 and then later on the A12 was closed, with a diversion through Ingatestone, which was very grim when you are tired.

[Mandat]

BlindedByTheLights said:

Technically based on what though? When all gantries are blank there are no NSL signs displayed anywhere so it is accepted as NSL.

The 60 limit doesn't end until you reach the next NSL sign.

The blank gantry means nothing itself, therefore the limit remains at 60.

[BlindedByTheLights]

andyb28 said:

Last night, after a very long drive from the Alps, we got off the tunnel and hit the M20.

There was a very serious crash on it, so I can fully understand the controls in place for that. However, later on down the road there were multiple lots of speed changes for no apparent reason at all. One of them said there was a stranded car, slowed everyone down to 40 in the end. When we finally got to the stranded car, it was completely away from the motorway lanes in a kind of layby. The other two occurrences appeared to be for no reason at all.

We had just driven 600 miles across the amazing French toll roads without a single issue, only to have this on the M20 and then later on the A12 was closed, with a diversion through Ingatestone, which was very grim when you are tired.

Unfortunately this is common on the m20, whoever control it seems to be utterly clueless or their visibility to control is not good enough.

The other day there was a car broken down halfway up the slip road off the m20, all four running lanes down to 40mph for it.

[The Gauge]

BlindedByTheLights said:

So my question is, what is the speed limit through the blank gantry 4

It is classed as an autobahn with no speed limit whatsoever. If you go fast enough you won't even be able to read the next sign so just keep going.

[BlindedByTheLights]

The Gauge said:

BlindedByTheLights said:

So my question is, what is the speed limit through the blank gantry 4

It is classed as an autobahn with no speed limit whatsoever. If you go fast enough you won't even be able to read the next sign so just keep going.

If only this were true, it’s actually the gantries causing the traffic most of the time. It is set out anywhere that overhead gantry limit remains until notified otherwise? I couldn’t find it when searching earlier.

[Scrump]

BlindedByTheLights said:

If only this were true, it’s actually the gantries causing the traffic most of the time. It is set out anywhere that overhead gantry limit remains until notified otherwise? I couldn’t find it when searching earlier.

I think it is not specific to overhead gantries, any speed limit remains in place until it is signed otherwise.
(I will be disappointed if PH doesn’t respond to this with some exception )

[BlindedByTheLights]

Scrump said:

BlindedByTheLights said:

If only this were true, it’s actually the gantries causing the traffic most of the time. It is set out anywhere that overhead gantry limit remains until notified otherwise? I couldn’t find it when searching earlier.

I think it is not specific to overhead gantries, any speed limit remains in place until it is signed otherwise.
(I will be disappointed if PH doesn’t respond to this with some exception )

Just found this so I believe you are correct and my suspicion that the blank gantry on the one with speed cameras is a revenue collector…

“A speed limit displayed inside a red circle is legally enforceable. If you go over the speed limit, you’re breaking the law and could receive a fine. We’ll let you know when it no longer applies by setting the national speed limit sign.

If no speed limits are displayed then the national speed limit applies. When speed limits are displayed, they remain in place until notified that they have ended, or a different speed limit is displayed.“

[andyb28]

BlindedByTheLights said:

Just found this so I believe you are correct and my suspicion that the blank gantry on the one with speed cameras is a revenue collector…

“A speed limit displayed inside a red circle is legally enforceable. If you go over the speed limit, you’re breaking the law and could receive a fine. We’ll let you know when it no longer applies by setting the national speed limit sign.

If no speed limits are displayed then the national speed limit applies. When speed limits are displayed, they remain in place until notified that they have ended, or a different speed limit is displayed.“

Surely there is a danger of new people joining the motorway and being unaware of the new speed limit?

[BlindedByTheLights]

andyb28 said:

BlindedByTheLights said:

Just found this so I believe you are correct and my suspicion that the blank gantry on the one with speed cameras is a revenue collector…

“A speed limit displayed inside a red circle is legally enforceable. If you go over the speed limit, you’re breaking the law and could receive a fine. We’ll let you know when it no longer applies by setting the national speed limit sign.

If no speed limits are displayed then the national speed limit applies. When speed limits are displayed, they remain in place until notified that they have ended, or a different speed limit is displayed.“

Surely there is a danger of new people joining the motorway and being unaware of the new speed limit?

Just noticed that the information I copied from the gov website above has been withdrawn and now directs to highways webpage that has no information about it other than some propaganda videos about how great smart motorways are. So I’m none the wiser again in finding a definitive answer

[BlindedByTheLights]

I am alright Jack said:

BlindedByTheLights said:

Just found this so I believe you are correct and my suspicion that the blank gantry on the one with speed cameras is a revenue collector…

“A speed limit displayed inside a red circle is legally enforceable. If you go over the speed limit, you’re breaking the law and could receive a fine. We’ll let you know when it no longer applies by setting the national speed limit sign.

If no speed limits are displayed then the national speed limit applies. When speed limits are displayed, they remain in place until notified that they have ended, or a different speed limit is displayed.“

I am alright Jack said:

Technically 60, but you wont receive a ticket from the camera on the gantry with nothing displayed for driving at the nsl.

Thanks, but where is this set out? I cannot find anything in the Highway Code relating to it. And technically and shouldn’t are a bit dodgy if a ticket was issued, the m20 cameras are like a rave some days

[119]

andyb28 said:

BlindedByTheLights said:

Just found this so I believe you are correct and my suspicion that the blank gantry on the one with speed cameras is a revenue collector…

“A speed limit displayed inside a red circle is legally enforceable. If you go over the speed limit, you’re breaking the law and could receive a fine. We’ll let you know when it no longer applies by setting the national speed limit sign.

If no speed limits are displayed then the national speed limit applies. When speed limits are displayed, they remain in place until notified that they have ended, or a different speed limit is displayed.“

Surely there is a danger of new people joining the motorway and being unaware of the new speed limit?

If there was an onslip before the next gantry, then that one would display the current temp limit.

[BossHogg]

BlindedByTheLights said:

Unfortunately this is common on the m20, whoever control it seems to be utterly clueless or their visibility to control is not good enough.

The other day there was a car broken down halfway up the slip road off the m20, all four running lanes down to 40mph for it.

If it's just a speed limit with no message, they're usually set automatically by the sensors in the road reading slow moving traffic, speed limits with a message set - lane closure, debris, pedestrian, animals etc are usually set by a control room operator.

[OutInTheShed]

andyb28 said:

Last night, after a very long drive from the Alps, we got off the tunnel and hit the M20.

There was a very serious crash on it, so I can fully understand the controls in place for that. However, later on down the road there were multiple lots of speed changes for no apparent reason at all. One of them said there was a stranded car, slowed everyone down to 40 in the end. When we finally got to the stranded car, it was completely away from the motorway lanes in a kind of layby. The other two occurrences appeared to be for no reason at all.

We had just driven 600 miles across the amazing French toll roads without a single issue, only to have this on the M20 and then later on the A12 was closed, with a diversion through Ingatestone, which was very grim when you are tired.

I think the limit setting is largely automated and is supposed to massage the flow of traffic.
The reason you didn't see anything at the end of your 40 limit is that you were slowed to allow the congestion to go away, rather than your group of cars making it worse.
I'm not experessing that very well, but it isn't just some bloke who flicks a switch labelled '40' and goes off for a sandwich.

[BlindedByTheLights]

BossHogg said:

BlindedByTheLights said:

Unfortunately this is common on the m20, whoever control it seems to be utterly clueless or their visibility to control is not good enough.

The other day there was a car broken down halfway up the slip road off the m20, all four running lanes down to 40mph for it.

If it's just a speed limit with no message, they're usually set automatically by the sensors in the road reading slow moving traffic, speed limits with a message set - lane closure, debris, pedestrian, animals etc are usually set by a control room operator.

I was waiting for you to come and bring your highways knowledge boss Hogg! So this case would have been an operator, I am all for safety (like having hard shoulders) but this seemed overly conservative and getting everyone down to 40mph a bigger risk than the car on the slip road on the hard shoulder.

[BlindedByTheLights]

I am alright Jack said:

BlindedByTheLights said:

Thanks, but where is this set out? I cannot find anything in the Highway Code relating to it. And technically and shouldn’t are a bit dodgy if a ticket was issued, the m20 cameras are like a rave some days

Because there is not a lowered limit displayed on the gantry to take a picture of to prove you were exceeding it. That's how they work.

Who says it couldn’t be a police officer in an unmarked or marked car? I am playing devils advocate a bit here so don’t take it personally. For something that could affect my insurance and my career as it could for others, it doesn’t seem clear or written down anywhere

Red x is clearly a closed lane, but if the next gantry is blank then the lane is open, there’s nothing to say open again. So it is reasonable that drivers may apply this same logic that once a reduced limit is no longer applied then it’s over?

Edited by BlindedByTheLights on Saturday 2nd March 20:23

[Ian Geary]

OutInTheShed said:

I think the limit setting is largely automated and is supposed to massage the flow of traffic.

The reason you didn't see anything at the end of your 40 limit is that you were slowed to allow the congestion to go away, rather than your group of cars making it worse.

I'm not experessing that very well, but it isn't just some bloke who flicks a switch labelled '40' and goes off for a sandwich.

This might be controversial, but I wonder why they don't speed traffic up to clear congestion?

If more people would just get a bloody move on, we could probably revert to having the hard shoulder again.

[BlindedByTheLights]

Ian Geary said:

OutInTheShed said:

I think the limit setting is largely automated and is supposed to massage the flow of traffic.

The reason you didn't see anything at the end of your 40 limit is that you were slowed to allow the congestion to go away, rather than your group of cars making it worse.

I'm not experessing that very well, but it isn't just some bloke who flicks a switch labelled '40' and goes off for a sandwich.

This might be controversial, but I wonder why they don't speed traffic up to clear congestion?

If more people would just get a bloody move on, we could probably revert to having the hard shoulder again.

Yep the variables are usually causing the bunching. And don’t get me started on lane discipline. It seems the only reason we got rid of hard shoulders was to create another lane to hog!