Dangerous variable speed limits on M4 Newport

HO87

The Brynglas tunnels have been a pain for years. I bet there are a few AM's who are beginning to regret binning the M4 Toll proposal which would have taken out the entire section from J23 to just west of J28. WAG would wipe out their entire budget to build it, apparently, but at least no one would have to go through Newport anymore. If they paid the toll of course.

Lum

They'd also make a killing every time they randomly close the J24 -> J28 stretch for no discernible reason and send you down the A48 with all it's roundabouts and traffic lights and completely random speed limits.

daveyjp

Wig wrote: »

So I was driving back home the other night 10.30pm, came across the bridge and the 50 signs were there approching the toll booths "50 in 3/4 mile" that's the way it should be done, so I slowed to 50.

Then later, going through all the gantries at Newport all of them switched off so doing a steady 68mph. When all of a sudden approaching the next gantry it was lit up at 50mph I only noticed at about 100 feet away, so I had to slam on the anchors to avoid a ticket. Luckily no one behind me, I was in the 3rd lane.

FYI the gantries in Newport M4 all have gatso lines underneath them and you don't know which ones have Gatsos on the back of them they all have camera signs on them. They are mandatory speed limit signs -when they are illuminated-.

I believe it was the second one before the tunnel, which I braked for. The one after that (the first one before the tunnel) was also lit up at "50" but this one was very dim, the leds were like they were on 30% of normal voltage so I didn't know what was going on. I was actually wondering if it was an optical illusion and it was actually not switched on at all.

Why did I not see it till the last second? Possibly there is a bend in the road as you approach, possibly the LED lights were not visible from that angle of looking at the gantry on approach. It was dark, I was concentrating on the road ahead, I was tired but not overly tired so that I was unsafe.

There was certainly no chance of me returning and going back to the previous junction to have another run at it to see if it was me or the gantry position that was mostly at fault.

But I think that to suddenly change the speed limit like that on a motorway with no prior warning (like there is at the bridge tolls and standard procedure at roadworks) is incredibly stupid and could easily cause an accident.

Why not put a warning on the previous gantry (the third one from the tunnel)? Like at the toll booths.

On a side note !!!!!! was the reduced limit for? The road was empty, there were no roadworks the tunnel was well lit and empty and the 50 limit was just for the tunnel it went back to NSL immmediately after the tunnel. !!!:mad:
On other occasions they don't restict the tunnel to 50 just for the hell of it, it's usually NSL.

EDIT:
Looking at the google map the bend is a left hand bend before the gantry in question, you have about 200m to see the gantry after rounding the bend, takes 3 seconds to do 100m at 70mph. 6 seconds to do the 200m assuming you see the gantry straight away, and assuming other factors like coming down the hill on approach does not further reduce your ability to see the LEDs lit up. You are looking in your mirror observing all the street furniture around you which complicates everything. Something else might have your attention within the car for a second.or 2. You might be overtaking other vehicles (like I was).
I don't think a 200metre warning (assuming it is visible at 200m) is long enough when you are travelling 70mph.
And remember after travelling through 6 - 7 - 10? gantries already showing no speed limit so you are lulled into believing the system is switched off at the moment.
They give you a half mile warning for the exit and 200m warning for a reduction in speed limit which if you fail to observe is a speeding ticket. And the bridge tols give you a 3/4 mile (36second) warning.

The bend is underneath Rembrandt Way, the gantry is at the sliproad exit for J25.

Old thread, but I experienced this on Thursday evening at about 9.30pm.

Very little traffic, no variable signs on at all from Celtic Manor junction where I joined. Came to the same stretch of road as the above to be confronted with a 40 limit on the gantry two out from the tunnel. Distance to react is not far at all, thank heavens no one was behind me. I had just pulled out to overtake a coach and he also hit the brakes, suggesting it wasn't down to me not being observant.

The gantry before the tunnel was set to 50 and the coach overtook me as we entered the tunnel, obviously testing the 10% +2 rule. After the tunnel back to NSL. There was no reason at all for there to be a 40 limit set for one gantry.

The other one which is blind is the first gantry as you enter the M42 northbound section, but in my experience this is only on in heavy traffic and you aren't doing 70 so slowing isn't a problem.

MostlyPuzzled

Right,

I'm just back from a round trip from Bristol to a place past Cardiff and after experiencing the variable speed limit gantries along the M4 I'm writing this with the main purpose of checking whether I'm on pills or something.

Is it just me and a handful of people in the whole country the only ones seeing this, not only as yet another money-making scheme, but plain dangerous? Is criminal an overstatement?

Saturday morning between 7 and 8 am. You flash a 50 sign on a motorway with fluid traffic and expect me to brake having a bloke just behind me doing 70? What's the standard answer from the guys excusing this scheme on this very forum? There was a 'variable speed limit sign' a mile ago and that should've kept me on my toes? I'm the criminal if I didn't see it? What about the guy just behind me doing 70? If he rams me he has commited a criminal offence and that should give me comfort when I'm in a wheelchair? Oh, I hear you, it's the same as hitting a 30 sign at the end of a 40 stretch and having someone behind you doing 40, isn't it? Clever you! What planet exactly do you live on?

Who is accountable for coming up with this system? Are they untouchable? Cannot you charge someone with devising what is essentially an accident waiting to happen? Is anyone doing something about this? Is there no other choice for the regular citizen but to bow down and get on with it?

SHIPSHAPE

MostlyPuzzled wrote: »

Saturday morning between 7 and 8 am. You flash a 50 sign on a motorway with fluid traffic and expect me to brake having a bloke just behind me doing 70? What's the standard answer from the guys excusing this scheme on this very forum? There was a 'variable speed limit sign' a mile ago and that should've kept me on my toes? I'm the criminal if I didn't see it? ?

Well, it would be your fault for not taking notice of motorway signs in the first place.

The variable speed limits on that strech of road has greatly improved the congestion and it quite clearly gives you enough time to adjust your driving speed.

How am I able to drive that strech of road regularly with no problems at all?

Indeed, how am I able to drive on unfamiliar roads throughout the UK with similar variable speed limits and still have no problems?

Why is driving such a difficulty for you? Ever considered hanging up your keys instead to lead a less stressful life?

MostlyPuzzled

SHIPSHAPE wrote: »

Well, it would be your fault for not taking notice of motorway signs in the first place.

The variable speed limits on that strech of road has greatly improved the congestion and it quite clearly gives you enough time to adjust your driving speed.

How am I able to drive that strech of road regularly with no problems at all?

Indeed, how am I able to drive on unfamiliar roads throughout the UK with similar variable speed limits and still have no problems?

Why is driving such a difficulty for you? Ever considered hanging up your keys instead to lead a less stressful life?

As predictable you missed the point completely. Not you particularly. Someone was going to, I mean.

How am I sure the guy behind me did see the sign? People around me, get it? I thought good driving was about adapting to the circumstances around you, not keeping an eye out for when authorities plan to trip you up. For your own good, apparently.

A 50 sign with a camera just behind it on a motorway and your response is boasting your great driving skills. Much appreciated, man.

daveyjp

Shipshape. I agree they do improve the flow very well when busy, it's when it isn't busy and a reduced speed is showing that really gets to drivers, especially when the only sign with a reduced limit is the one hidden by a bridge!

dacouch

You've only got to reduce your speed by 20% or less if you're travelling at 70mph, you could achieve this without slamming on your brakes

MostlyPuzzled

dacouch wrote: »

You've only got to reduce your speed by 20% or less if you're travelling at 70mph, you could achieve this without slamming on your brakes

Let's see if I can articulate it because I think it'll do me good too. Beware, by the way, I'm talking in general without any intention to have a go at Dacouch in particular.

I find an almost self-evident principle that it's good to alleviate the driver's workload. Remarks like "well, if you consider keeping an eye open for a 50 sign is an unacceptable increase in workload you should maybe start using the train, mate", while terribly amusing, add little to the issue at hand.

We share the road with many other drivers (shocking news) and there'll always be some kind of Gaussian distribution of driving skills around us. Even perfectly good drivers will at some given point be affected by the onset of tiredness or some unpredictable distraction. Remarking "well, then they should stop", or "well, then the accident is their fault" sounds incredibly puerile and immature. As it does basking in the sunlight of your own driving awesomeness by contrast.

So accepting these lower end imperfections (shall we call them that) in the gaussian curve will always be present, it follows naturally everything in our hand should be done to keep things as simple as possible. Even if we make it simpler by a tiny bit. And even if you and I happen to be awesome drivers.

Surely I'm not reinventing the wheel, am I?

Now, asking people cruising at 70 on a motorway with perfectly fluid traffic to be on the lookout for phantom 50 signs, to me, and I hope I'm not alone in this, sounds as stupid as it comes. Specially when you could use that available electronically controlled system already at your fingertips to warn me along the lines of "Careful, speed limit of 50 starting on next gantry". Not on this gantry, please. That way I might be convinced that you're not just trying to trip me up by making up new stuff.

Unless, that is, you tell me that speed cameras only work, say, from the second gantry on after the first sign. In which case I would apologise for not understanding how the system works and say no more.

Last, but not least, reducing your speed from 70 to 50 mph means reducing it by 20 mph, or 20/70 = 0.2857 = 28.57% of your original speed. So actually closer to a not at all negligible 30% than it is to the '20% or less' stated.

dacouch

My figure of 20% is actually over generous, the speed camera will normally be set at 56mph + before they take a picture.

Assuming your speedy displays 70mph, your true speed will likely be nearer 66mph. The difference from true speed of 66mph to 56mph is nearer 15%.



I could adjust my speed for the above figures from siting a gantry speed sign without using the brake