20 limit on a motorway gantry?!

20 limit on a motorway gantry?!

Author
Discussion

mcgandalf

Original Poster:

654 posts

154 months

Tuesday 2nd September 2014
quotequote all
Can anyone tell me if I"m to expect a court summons for this...?

On the M4 going past Newport yesterday evening at around 11pm, the overhead gantries were displaying 50. Lane 1 was coned off for road works. I was in Lane 3 behind a 44-tonner who was sitting on the limiter at ~56. We were overtaking slower traffic in L2, travelling at 45-50.

This part of the M4 is very twisty and your view ahead is hampered by plenty of overhead obstructions (low bridges, tunnels etc).

We came to the end of the roadworks and another gantry. I was unable to read what was on the gantry as my view ahead was partially blocked by the HGV in front and a low bridge. I expected the limit to read 50 and I checked that my speedo was going to match this.

As the HGV in front went under the gantry I could finally see that it read...20 mph!! I had maybe 2 seconds to brake to >20, if I could.

Obviously i couldn't (and an emergency stop on the motorway would have been suicidal), and I went through the gantry at around 40mph. All other traffic around me was doing 40-56 mph through this gantry.

Is this 20 limit at all enforceable? It seemed a mistake for it to be on the sign at all (clear, dry conditions, no workforce in road etc). I've got a fuzzy recollection that 40 is the minimum enforceable speed on a motorway - is this at all correct?

ACPO guidelines suggest a summons would be issued for speeds above 35 in a 20 limit - I was certainly doing that, but so was all other traffic on the road. Are we all to expect to be dragged in front of the beak and receive driving bans?!

Pebbles167

3,417 posts

151 months

Tuesday 2nd September 2014
quotequote all
I've been working in Cardiff for the last few weeks (live in Bath) and this has been driving me mad. Stupid limits on the gantries are causing massive trouble. Obviously someone else had the same problem as you this morning at around 4-5am, only they decided to slam on and piled their SLK into the side of the bridge.

For what its worth I've hit a few gantries at over their limit and have not heard anything.

littleredrooster

5,523 posts

195 months

Tuesday 2nd September 2014
quotequote all
AFAIK it's the next gantry down the road which enforces the limit, not the one directly behind the sign. Other than for an oncoming vehicle, I didn't think 20 was one of the available options on a managed motorway.

Pebbles167

3,417 posts

151 months

Tuesday 2nd September 2014
quotequote all
littleredrooster said:
AFAIK it's the next gantry down the road which enforces the limit, not the one directly behind the sign. Other than for an oncoming vehicle, I didn't think 20 was one of the available options on a managed motorway.
I dont think any of them work, every day I see loads of vehicles fly past them. A lot of them are local and presumably know they are out of action.

covboy

2,573 posts

173 months

Tuesday 2nd September 2014
quotequote all
littleredrooster said:
AFAIK it's the next gantry down the road which enforces the limit, not the one directly behind the sign. Other than for an oncoming vehicle, .
Where did you get idea from ?


Firstly is it a "managed" section of motorway with compulsory limit signs (Inside the red circles)

Secondly if the OP was travelling so close to the truck (even at 50 ish) so as not being able to see them, I think perhaps he was too close !

LoonR1

26,988 posts

176 months

Tuesday 2nd September 2014
quotequote all
20 does seem low. The minimum speed on a free flowing motorway is 30 IIRC.

However my tip would be to back off the lorry a bit. If you find it difficult to read signs when following one, it's because you are too close.

littleredrooster

5,523 posts

195 months

Tuesday 2nd September 2014
quotequote all
covboy said:
Firstly is it a "managed" section of motorway with compulsory limit signs (Inside the red circles)
Ahhh...I might have misread the OP. I doubt that Wales is that advanced, come to think of it. smile
If no red circle, then only advisory limit. I'll put me glasses on next time.

covboy said:
Secondly if the OP was travelling so close to the truck (even at 50 ish) so as not being able to see them, I think perhaps he was too close !
Completely agree.

scarble

5,277 posts

156 months

Tuesday 2nd September 2014
quotequote all
Like everyone has said already, you were too close, idjut.

Managed speeds are often ridiculous but that's no excuse for being a s**t driver.

mcgandalf

Original Poster:

654 posts

154 months

Tuesday 2nd September 2014
quotequote all
This was the gantry (look straight ahead):

https://maps.google.com/maps?q=Newport,+UK&hl=...

See how your forward view of the gantries, on this stretch of managed motorway, is severely hampered by twists and turns and low bridges? I was following the HGV at an entirely safe distance (for stopping purposes), but the size of that vehicle only served to further block my view.

All speed limits were displayed in red circles (i.e. not the flashing yellow advisory types).

The gantry a couple of hundred yards behind was clearly showing 50 - this had been the limit ever since the Bryn Glas tunnels.

If I had seen the (nonsensical) 20 limit displayed, absolutely slammed on the anchors to decelerate from 50 to 20 and then been rear ended as a result - am I expected to feel all warm and fuzzy that, despite the fact that I am now in a wheelchair, the chap behind me was breaking the law?

The 20 limit was quite clearly a mistake - good road conditions, free flowing traffic and no oncoming vehicles! Would this actually be enforced, or enforceable, if someone had simply pressed the wrong button in a Highways Agency/Traffic Wales control room?

cibble10

722 posts

118 months

Tuesday 2nd September 2014
quotequote all
I had a run of this sort of cr*p one early morning on the M25. I was snarled in traffic for almost 90 mins, having covered only a couple of junctions then the road miraculously cleared but with the gantries displaying 40s and then 30s and I could see but a handful of cars. I was then well behind schedule to catch a ferry so broke each limit by at least a 20% margin (and one a lot more). There was no danger to me or anyone else, and how they came to be set so low for many miles was beyond me. To the point, nothing came of at least 5 infringements...

covboy

2,573 posts

173 months

Tuesday 2nd September 2014
quotequote all
mcgandalf said:
See how your forward view of the gantries, on this stretch of managed motorway, is severely hampered by twists and turns and low bridges? I was following the HGV at an entirely safe distance (for stopping purposes), but the size of that vehicle only served to further block my view.
As you have now found out - Safe travelling distance is not only about stopping distances

mcgandalf

Original Poster:

654 posts

154 months

Tuesday 2nd September 2014
quotequote all
covboy said:
As you have now found out - Safe travelling distance is not only about stopping distances
Would you have also done an almost-emergency stop in the outside lane of a free-flowing motorway with a Transit up your arse because (and only because) of a little number displayed on a gantry above your head?

covboy

2,573 posts

173 months

Tuesday 2nd September 2014
quotequote all
mcgandalf said:
Would you have also done an almost-emergency stop in the outside lane of a free-flowing motorway with a Transit up your arse because (and only because) of a little number displayed on a gantry above your head?
No – I would hopefully be travelling far enough behind the vehicle in front (no matter what type) to see the overhead gantries in advance and adjust my speed accordingly well beforehand.

mcgandalf

Original Poster:

654 posts

154 months

Tuesday 2nd September 2014
quotequote all
covboy said:
No – I would hopefully be travelling far enough behind the vehicle in front (no matter what type) to see the overhead gantries in advance and adjust my speed accordingly well beforehand.
I was referring to any traffic behind you which might slam into your rear if you suddenly decided to slam on the anchors.

All other traffic cracked on through the 20 gantry at 40-50 mph - and after another couple of hundred yards there was another gantry displaying the NSL sign.

Will Newport magistrates find themselves dishing out a sudden flurry of driving bans because Traffic Wales pressed the 20 button instead of the 50 button in the M4 control room?

Mr Freefall

2,323 posts

257 months

Tuesday 2nd September 2014
quotequote all
mcgandalf said:
This was the gantry (look straight ahead):

https://maps.google.com/maps?q=Newport,+UK&hl=...

See how your forward view of the gantries, on this stretch of managed motorway, is severely hampered by twists and turns and low bridges? I was following the HGV at an entirely safe distance (for stopping purposes), but the size of that vehicle only served to further block my view.

All speed limits were displayed in red circles (i.e. not the flashing yellow advisory types).

The gantry a couple of hundred yards behind was clearly showing 50 - this had been the limit ever since the Bryn Glas tunnels.

If I had seen the (nonsensical) 20 limit displayed, absolutely slammed on the anchors to decelerate from 50 to 20 and then been rear ended as a result - am I expected to feel all warm and fuzzy that, despite the fact that I am now in a wheelchair, the chap behind me was breaking the law?

The 20 limit was quite clearly a mistake - good road conditions, free flowing traffic and no oncoming vehicles! Would this actually be enforced, or enforceable, if someone had simply pressed the wrong button in a Highways Agency/Traffic Wales control room?
If you click on to street view, go past the Gantry, then turn the view 180 degrees you can see the back on the gantry, and that there are no cameras on this gantry.

You might be safe...

scarble

5,277 posts

156 months

Tuesday 2nd September 2014
quotequote all
mcgandalf said:
I was referring to any traffic behind you which might slam into your rear if you suddenly decided to slam on the anchors.
If you were leaving an appropriate gap to the vehicle in front you wouldn't need to slam anything, you'd be able to gradually reduce your speed such that vehicles behind would have time to react.
From the street view, which has a disadvantageous angle due to being on a big pole on top of the car, the visibility of the sign is hardly obstructed by the bridge.

mcgandalf

Original Poster:

654 posts

154 months

Tuesday 2nd September 2014
quotequote all
Am I correct in thinking (thanks to a previous post on PH) that the minimum enforceable speed limit on a motorway is 40 mph? Or is that just my imagination?

speedking31

3,543 posts

135 months

Tuesday 2nd September 2014
quotequote all
In another thread it was stated that the 50 shown in the OP's Google street view would apply to all 3 lanes (common sense). I can't understand that. But then if the intent was to have NSL in lanes 2 and 3, why not show NSL roundels above those lanes?

I realise that there are different lane divider markings between lanes 1 and 2, but its not written anywhere that that dictates the applicability of any speed limit.

OP which lane were you in? It is feasible that lane 1 showed a different limit from lanes 2 and 3.

mcgandalf

Original Poster:

654 posts

154 months

Tuesday 2nd September 2014
quotequote all
speedking31 said:
In another thread it was stated that the 50 shown in the OP's Google street view would apply to all 3 lanes (common sense). I can't understand that. But then if the intent was to have NSL in lanes 2 and 3, why not show NSL roundels above those lanes?

I realise that there are different lane divider markings between lanes 1 and 2, but its not written anywhere that that dictates the applicability of any speed limit.

OP which lane were you in? It is feasible that lane 1 showed a different limit from lanes 2 and 3.
I was in Lane 3, overtaking slower traffic in Lane 2. Lane 1 was closed due to road works. The gantries were displaying a red cross for L1 and - at the point I'm talking about - 20 limits for L2 and L3. For the previous mile or so the gantries had been displaying 50 limits for L2 and L3, with a red cross for the closed L1.

Much as I'm being lambasted for supposedly tailgating an HGV, my point is that 20 is an extremely dangerous speed to drive at on a live motorway, unless so compelled by sheer weight of traffic, or - as littleredrooster pointed out - an oncoming vehicle. Neither were present on this clear, free-flowing stretch of motorway in the late evening.

Braking from 50 to 20 at a moment's notice - and, yes, it was a moment's notice (sightlines on that stretch of the M4 really are bloody awful, regardless of whether you're behind an HGV or a Caterham) - is effectively suicidal.

devnull

3,745 posts

156 months

Tuesday 2nd September 2014
quotequote all
OP, were you travelling westbound or eastbound?

West bound, there are 2 sets of cameras on the gantries. 1st set is on the 2nd gantry after the start of the start of the managed section, the second set is the second gantry out of the tunnels.

Eastbound, there are two sets also, first set is immediately before the caerleon exit, the second set is is the second gantry out of the tunnels.


Just saw your google maps link, theres no camera on that gantry. Quit yer flapping smile