M60 Junction 18 Simister Island Interchange

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Bryn666
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Re: M60 Junction 18 Simister Island Interchange

Post by Bryn666 »

jackal wrote: Mon Jan 10, 2022 11:02 NCE report that
National Highways has launched a consultation on its plans to close a gap in the M60 motorway around Manchester. National Highways has launched a consultation on its plans to close a gap in the M60 motorway around Manchester.

England’s major roads operator announced its preferred route for the Simister Island Interchange in January 2021 and has been working on preliminary designs since.
I haven't been able to find any consultation page but I guess it will open soon.

https://www.newcivilengineer.com/latest ... 022/?tkn=1
Hopefully the loop is still the preferred option and not been scaled back to the multi-lane signal drivel alternative.
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jackal
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Re: M60 Junction 18 Simister Island Interchange

Post by jackal »

It seems there's a delay on the consultation:

https://nationalhighways.co.uk/our-work ... st-updates
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Re: M60 Junction 18 Simister Island Interchange

Post by jackal »

My suspicion was already that the delay was due to the ALR aspect of the scheme, and with the smart motorway announcement I'm sure of it. I imagine there's a hasty redesign of J17-18 as D5M with discontinuous hard shoulders. Unfortunately this is likely to delay things significantly.
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Re: M60 Junction 18 Simister Island Interchange

Post by Bryn666 »

jackal wrote: Wed Jan 12, 2022 17:35 My suspicion was already that the delay was due to the ALR aspect of the scheme, and with the smart motorway announcement I'm sure of it. I imagine there's a hasty redesign of J17-18 as D5M with discontinuous hard shoulders. Unfortunately this is likely to delay things significantly.
There's very limited room for conventional D5M there (excluding through structures), I really think a 500 metre length of D5 ALR would be much safer than even more narrow lanes as per J12-15 and through 17 itself. I hope this is not going to delay progressing this scheme; it should not be impossible to provide a design as a worst case scenario retaining the eastbound D4M - fixing the westbound merges before J17 is much more important IMO.
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Chris5156
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Re: M60 Junction 18 Simister Island Interchange

Post by Chris5156 »

Bryn666 wrote: Wed Jan 12, 2022 18:55
jackal wrote: Wed Jan 12, 2022 17:35 My suspicion was already that the delay was due to the ALR aspect of the scheme, and with the smart motorway announcement I'm sure of it. I imagine there's a hasty redesign of J17-18 as D5M with discontinuous hard shoulders. Unfortunately this is likely to delay things significantly.
There's very limited room for conventional D5M there (excluding through structures), I really think a 500 metre length of D5 ALR would be much safer than even more narrow lanes as per J12-15 and through 17 itself. I hope this is not going to delay progressing this scheme; it should not be impossible to provide a design as a worst case scenario retaining the eastbound D4M - fixing the westbound merges before J17 is much more important IMO.
It could just be a question of semantics. If it includes 500m of ALR, but there are some bits of discontinuous hard shoulder somewhere on the widened stretch, then NH can justifiably call it something other than a Smart Motorway and they can also justifiably say they’re providing a widening project with hard shoulders. You just need enough hard shoulder to stop it looking too much like ALR.
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Re: M60 Junction 18 Simister Island Interchange

Post by KILLER KNIGHT »

The Inner Links Option was better than the Northern Loop Option.
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Re: M60 Junction 18 Simister Island Interchange

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KILLER KNIGHT wrote: Sat Feb 04, 2023 12:58 The Inner Links Option was better than the Northern Loop Option.
It very much was not.
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Re: M60 Junction 18 Simister Island Interchange

Post by KILLER KNIGHT »

jackal wrote: Sat Feb 04, 2023 17:26
KILLER KNIGHT wrote: Sat Feb 04, 2023 12:58 The Inner Links Option was better than the Northern Loop Option.
It very much was not.
Why not? Also, the start date has been delayed by a year but the completion date has been delayed by 3 years.
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Re: M60 Junction 18 Simister Island Interchange

Post by jackal »

KILLER KNIGHT wrote: Sun Feb 05, 2023 21:17
jackal wrote: Sat Feb 04, 2023 17:26
KILLER KNIGHT wrote: Sat Feb 04, 2023 12:58 The Inner Links Option was better than the Northern Loop Option.
It very much was not.
Why not?
Because you shouldn't have to go through signalised at-grade junctions to continue along a major orbital motorway (the M60 clockwise).
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Re: M60 Junction 18 Simister Island Interchange

Post by KILLER KNIGHT »

jackal wrote: Mon Feb 06, 2023 09:59
KILLER KNIGHT wrote: Sun Feb 05, 2023 21:17
jackal wrote: Sat Feb 04, 2023 17:26
It very much was not.
Why not?
Because you shouldn't have to go through signalised at-grade junctions to continue along a major orbital motorway (the M60 clockwise).
Was it not free flowing?
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Re: M60 Junction 18 Simister Island Interchange

Post by fras »

M60 Anticlockwise to M62 Westbound is free flow. M62 Eastbound to M60 Clockwise involves the signalised roundabout. You can easily see what is involved using Google Street View. (3 sets of traffic lights).
The proposed 270 degree loop to give free flow to the M62 Eastbound -> M60 CLockwise can be built on undeveloped land, and off-line for the most part and has to be the best option in the circumstances. Anything else really needs the whole junction demolishing and 4=level junction a la Almondsbury, and that definiteley ain't going to happen. Having said that, I do have my doubts about the radius of what is a very long and tight curve. I would be better to increase the radius and come onto the M60 Clockwise a bit further north, but then the golf club has to be intruded upon. If you read the HS2 petitions and hearings on golf clubs for Phase 1, you soon realise that it's best not to go there !
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Re: M60 Junction 18 Simister Island Interchange

Post by jackal »

KILLER KNIGHT wrote: Mon Feb 06, 2023 11:23
jackal wrote: Mon Feb 06, 2023 09:59
KILLER KNIGHT wrote: Sun Feb 05, 2023 21:17

Why not?
Because you shouldn't have to go through signalised at-grade junctions to continue along a major orbital motorway (the M60 clockwise).
Was it not free flowing?
Nope. You can see it in all it's glory here from 2.00:

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Re: M60 Junction 18 Simister Island Interchange

Post by nearM65 »

Just watched the fly through on YouTube and hopefully it may sort this junction out.. looks abit complicated though.. some people can't even use a normal roundabout so god help them when this is built.. whats the time frame for starting construction etc?.. i think ill keep well away when thats being built 😆..
5000 miles a month and counting.. :D
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Re: M60 Junction 18 Simister Island Interchange

Post by fras »

nearM65 wrote: Mon Feb 06, 2023 18:59 Just watched the fly through on YouTube and hopefully it may sort this junction out.. looks abit complicated though.. some people can't even use a normal roundabout so god help them when this is built.. whats the time frame for starting construction etc?.. i think ill keep well away when thats being built 😆..
Of course if you miss the "Big Loop", you can always go round the existing roundabout !
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Re: M60 Junction 18 Simister Island Interchange

Post by KILLER KNIGHT »

fras wrote: Mon Feb 06, 2023 20:11
nearM65 wrote: Mon Feb 06, 2023 18:59 Just watched the fly through on YouTube and hopefully it may sort this junction out.. looks abit complicated though.. some people can't even use a normal roundabout so god help them when this is built.. whats the time frame for starting construction etc?.. i think ill keep well away when thats being built 😆..
Of course if you miss the "Big Loop", you can always go round the existing roundabout !
Unfortunately, this option wasn’t the preferred route because it didn’t get enough votes.
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Re: M60 Junction 18 Simister Island Interchange

Post by jackal »

Just to be clear, the preferred option is based on the Northern Loop (not the Inner Link). Here is the Northern Loop video:

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Re: M60 Junction 18 Simister Island Interchange

Post by KILLER KNIGHT »

fras wrote: Mon Feb 06, 2023 12:21 M60 Anticlockwise to M62 Westbound is free flow. M62 Eastbound to M60 Clockwise involves the signalised roundabout. You can easily see what is involved using Google Street View. (3 sets of traffic lights).
The proposed 270 degree loop to give free flow to the M62 Eastbound -> M60 CLockwise can be built on undeveloped land, and off-line for the most part and has to be the best option in the circumstances. Anything else really needs the whole junction demolishing and 4=level junction a la Almondsbury, and that definiteley ain't going to happen. Having said that, I do have my doubts about the radius of what is a very long and tight curve. I would be better to increase the radius and come onto the M60 Clockwise a bit further north, but then the golf club has to be intruded upon. If you read the HS2 petitions and hearings on golf clubs for Phase 1, you soon realise that it's best not to go there !
That’s exactly why the second option is better. You have a signalised junction but it is still an improvement because all of the movements were direct.
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Re: M60 Junction 18 Simister Island Interchange

Post by Chris5156 »

KILLER KNIGHT wrote: Thu Feb 09, 2023 19:44
fras wrote: Mon Feb 06, 2023 12:21M60 Anticlockwise to M62 Westbound is free flow. M62 Eastbound to M60 Clockwise involves the signalised roundabout. You can easily see what is involved using Google Street View. (3 sets of traffic lights).
The proposed 270 degree loop to give free flow to the M62 Eastbound -> M60 CLockwise can be built on undeveloped land, and off-line for the most part and has to be the best option in the circumstances. Anything else really needs the whole junction demolishing and 4=level junction a la Almondsbury, and that definiteley ain't going to happen. Having said that, I do have my doubts about the radius of what is a very long and tight curve. I would be better to increase the radius and come onto the M60 Clockwise a bit further north, but then the golf club has to be intruded upon. If you read the HS2 petitions and hearings on golf clubs for Phase 1, you soon realise that it's best not to go there !
That’s exactly why the second option is better. You have a signalised junction but it is still an improvement because all of the movements were direct.
It depends what you mean by better.

If your measure is just how direct everything is - as in, how short a distance you need to travel - then yes, the second option is better because all the turning movements take as short a path as possible through the junction.

But the junction is solely for motor traffic so distance travelled is not the key metric to consider in design. If your measure is how quickly you can get through the junction, then the first option wins: travelling around the loop will be about 0.9 to 1km further for traffic travelling M60 eastbound to M60 southbound, but at 50mph that distance will take about 44 seconds. In option 2 you could be sitting at the stop line for that long waiting to get through the lights, and even when you're moving you won't be travelling at 50 because you'll be negotiating multiple signalised junctions and more than one sharp curve.

Another important metric is capacity. A two-lane looped sliproad can carry many more vehicles per hour than a two lane road passing through multiple traffic signals, and because it is removing the heaviest flow of traffic from the roundabout, can significantly improve journey times for the other three right-turn movements as well. That's because M60 eastbound to M60 southbound traffic currently demands the longest green time to clear the junction, holding other movements on red; by removing that traffic altogether you redistribute the green light time to the other three movements and all three of them benefit. With option 2 you can't do that - you can't really do more than fiddle with the existing signal timings - and the only capacity benefits are from providing slightly faster left turns and slightly more queueing space. Those changed signal timings in option 1 also make transit times through the junction shorter for all right turn movements.

So option 1 wins in terms of capacity and travel time, and only gives a disbenefit to "directness" for one of the eight turning movements the junction handles. Option 2, on the other hand, wins on directness for that one turning movement, but loses out for capacity and travel time for all eight turning flows.

As a result, I'm with Jackal. Option 1 all the way.
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Re: M60 Junction 18 Simister Island Interchange

Post by fras »

How any option using the existing roundabout was even posited, I fail to see. The roundabout needs abolishing and replaced with a 4-level stack, but obviously that won't happen, so it has to be Option 1 "The Loop". I hope they bank it up a bit, although not like Brooklands !
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Re: M60 Junction 18 Simister Island Interchange

Post by jackal »

fras wrote: Thu Feb 09, 2023 20:17 How any option using the existing roundabout was even posited, I fail to see. The roundabout needs abolishing and replaced with a 4-level stack, but obviously that won't happen
Not as outlandish a suggestion as it would have been prior to the Lofthouse proposal, though there are the key differences that (1) the Lofthouse roundabout is on the top level and can therefore be replaced more easily with freeflow links and (2) Simister Village is very close, making an additional level (or two!) problematic.

Re (1), I have suggested that it might be possible to remove the roundabout and thread freeflow links between the carriageway levels, though this is pretty speculative and certainly more complex, for instance requiring the M62 mainline to be jacked up. So in the real world I'm pretty happy with the loop.
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