M181

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Bryn666
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Re: M181

Post by Bryn666 » Tue Jan 22, 2019 19:04

Berk wrote:
Tue Jan 22, 2019 16:23
Is the design developer proposed?? Can’t imagine HE would make such a mess of it.

But don’t they still have to consent before it’s handed over to local highways??
HE won't be bothered about losing mileage as it means they won't have to maintain it.
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Chris5156
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Re: M181

Post by Chris5156 » Tue Jan 22, 2019 19:40

Berk wrote:
Tue Jan 22, 2019 16:23
Is the design developer proposed?? Can’t imagine HE would make such a mess of it.
HE won't have designed the scheme, they aren't the ones who want anything to change. The design is produced by whoever wants the change to be made - in this case either Lincolnshire or the developer. As long as it meets the appropriate standards HE won't object because they won't be responsible for any of the resulting highway once it opens.
But don’t they still have to consent before it’s handed over to local highways??
They will consent because HE's interest will terminate at the give way line on the new roundabout. Whether the junction works won't be their problem. As long as their motorway has a compliant terminus they won't care whether Lincolnshire are choosing to make an entirely avoidable mess of their highway network.

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Re: M181

Post by TheKeymeister » Wed Jan 23, 2019 21:20

Bryn666 wrote:
Tue Jan 22, 2019 16:10
jgharston wrote:
Tue Jan 22, 2019 16:07
Browsing the Wiki trying to find an example to point at, the M6/A5022 junction illustrating Diamond interchange is exactly what I'd put there. The M181 already goes under the B1450, it "just" needs the four slip lanes.
A conventional diamond would interfere with the M180 trumpet, but a "compact" GSJ would fit within and, even if the limit was lowered to suit the reduced weaving space, would be better than a roundabout under a replacement bridge.
Is the bridge definitely a replacement? It looks to be on exactly the same alignment as the existing.

I must admit, at first glance I didn't realise the bridge was staying open to vehicular traffic and thought it was just being maintained for the benefit of NMUs. Now I've realised that's not the case, I agree it's a mess.

I could understand not retaining the existing bridge and converting to a diamond, as there's probably not the width for the right turn lanes on it, and adding a second bridge to convert to a roundabout GSJ would inherently be more expensive than a flat roundabout...but the currently proposed mess is just rubbish, especially if the bridge is indeed a replacement.

From the SABRE Wiki: Diamond interchange :

A Diamond Interchange is a compact and relatively low-cost Grade Separated Junction where the minor road and major road are connected by simple slips, with simple give way junctions at the end of the slip roads onto the minor road. This forms a rough diamond shape between the four slips.

Favoured for connections to B roads and quiet A roads in the early days of motorway building, many have needed to be improved over the years to cope with modern traffic levels. The easiest

... Read More

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Re: M181

Post by mark3evo » Wed Jan 23, 2019 21:58

that will put a stop to testing your acceleration of high powered car or bike exiting Scunthorpe or approaching 8-)

as you will never see a police car laid in wait on M181 :lol:

plus there are 4 bad undulations as if road subsidence noticeable at speed from Scunthorpe to M180

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Euan
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Re: M181

Post by Euan » Wed Jan 23, 2019 22:56

It should be worth remembering that some motorway spurs have their own "identity" (as in, a separate number) while others do not. Part of the M181 will remain motorway after the roundabout is built so a spur will still exist, but it will merely be under the M180 label. The length of the spur may well make it easier to decide whether it should have its own number as in this case the length is cut to the extent that there is no point in giving the spur a separate number.
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Re: M181

Post by JF2309 » Thu Jan 24, 2019 13:27

A North facing half diamond would solve this abomination.

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jackal
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Re: M181

Post by jackal » Sat Jan 26, 2019 01:33

If they put a compact GSJ in the slips would be a bit of a Redhouse situation, with A1077 in one direction and M180 spur in the other on the same section of S2. That's the kind of 'interesting' scenario that has consultants reaching for a roundabout, unfortunately.

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Re: M181

Post by Euan » Sat Jan 26, 2019 08:46

jackal wrote:
Sat Jan 26, 2019 01:33
If they put a compact GSJ in the slips would be a bit of a Redhouse situation, with A1077 in one direction and M180 spur in the other on the same section of S2. That's the kind of 'interesting' scenario that has consultants reaching for a roundabout, unfortunately.
It's certainly true that not every entrance to a motorway is separated from other roads by a roundabout, especially at the start of motorways. For an example of this look no further than Barnetby Interchange just along the M180: nothing stopping non-motorway traffic on the A180 "accidentally" continuing along the motorway.
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Re: M181

Post by jackal » Sat Jan 26, 2019 09:30

^ I wasn't saying anything about the mainline. My point was that if you put in a compact GSJ you'd have S2 slips with motorway in one direction and all-purpose in the other.

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Re: M181

Post by Bryn666 » Sat Jan 26, 2019 16:56

jackal wrote:
Sat Jan 26, 2019 09:30
^ I wasn't saying anything about the mainline. My point was that if you put in a compact GSJ you'd have S2 slips with motorway in one direction and all-purpose in the other.
Given the numerous motorway restriction screw ups recently such as the A14, A494, and A1(M) I doubt they'd be bothered.
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Re: M181

Post by delinquentwoody » Wed Feb 13, 2019 07:13

As this is quite local to me, I've had a read through the planning documents.

It turns out the bridge is actually the existing one, and they have been undecided what to do with this bridge. A revised and approved planning document shows the bridge still in situ, but now with no access to the roundabouts for vehicles - the bridge will only be for cyclists and pedestrians. All traffic will be required to pass through the new roundabout system, which just looks absolutely ridiculous! Why they couldn't have turned the bridge into something similar to J2 on the M180 I don't know.
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jackal
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Re: M181

Post by jackal » Wed Feb 13, 2019 16:36

^ That's the old plan, just with annotations to say what's changing.

Also as discussed earlier this seems to be only one of two roundabouts planned for the current M181 mainline, the other being further north at Brumby Common Lane:

https://www.greaterlincolnshirelep.co.u ... nction.jpg

I haven't been able to find any plans for the design but confusingly it seems to be planned for before the southern junction:

https://www.greaterlincolnshirelep.co.u ... -junction/

The access arrangements are extremely stingy for a £1.2bn project...
Last edited by jackal on Thu Feb 14, 2019 11:27, edited 1 time in total.

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Bryn666
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Re: M181

Post by Bryn666 » Thu Feb 14, 2019 08:32

Developers. Nuff said.

Now if they wanted a central spine road that's great but that will be solid with traffic because that development layout screams car dependency.

Also this Northern Powerhouse and Midlands Engine branding is the worst. It's meaningless drivel to big up projects that were overdue 25 years ago.
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Re: M181

Post by jackal » Thu Feb 14, 2019 11:25

Here's the final version of the southern junction:

M181 southern junction - Copy.PNG

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Re: M181

Post by Bryn666 » Thu Feb 14, 2019 11:32

jackal wrote:
Thu Feb 14, 2019 11:25
Here's the final version of the southern junction:


M181 southern junction - Copy.PNG
Ah great, a 3 lane circulatory with no spiralling either so not only will it be congested it will also have side-swipe collisions.

:facepalm: :facepalm: :facepalm: :facepalm: :facepalm:
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Re: M181

Post by Johnathan404 » Thu Feb 14, 2019 11:34

I assumed it had just been sketched like that to make the CAD easier. You mean they still build them like that? :x
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Re: M181

Post by Hdeng16 » Thu Feb 14, 2019 15:47

Don’t worry guys, It’ll be repainted as 2 lanes within 18 months like seemingly every other new roundabout built in the last 10 years.

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Re: M181

Post by ais523 » Thu Feb 14, 2019 16:49

Johnathan404 wrote:
Thu Feb 14, 2019 11:34
I assumed it had just been sketched like that to make the CAD easier. You mean they still build them like that? :x
The official guidance for roundabout marking is terrible. It basically goes "you can mark a roundabout like this, or like this, or like this…", giving a number of options, but not explaining why or when you'd use any of them. As a result, a large number of roundabouts end up with useless markings.

We could do with a standard for roundabout lane markings that actually guides developers to finding the best solution for the location. (For what it's worth, I can't see much reason to use markings other than spiral or turbo on a large roundabout, and small roundabouts are typically only one lane wide anyway.)

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Re: M181

Post by Stevie D » Thu Feb 14, 2019 21:49

Bryn666 wrote:
Thu Feb 14, 2019 11:32
Ah great, a 3 lane circulatory with no spiralling either so not only will it be congested it will also have side-swipe collisions.
I can't see why that roundabout would be busy enough to need 3 lanes on the approach or circulation. Yet another example of theory trumping reality.

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Re: M181

Post by Berk » Thu Feb 14, 2019 22:49

Even if you can’t stop the roundabout project from going ahead, are there no other ways to stop this design from going ahead??

Or would that have to be a judicial review?? :?

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