M6 J10 Improvements

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Jeni
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Re: M6 J10 Improvements

Post by Jeni »

Bryn666 wrote: Sun Mar 08, 2020 19:13
Jeni wrote: Sun Mar 08, 2020 19:07
jackal wrote: Sun Mar 08, 2020 17:12 It really is a disgraceful waste of public money that they're removing the existing freeflow left turn.
I wouldn't quite say "disgraceful" or "waste"
Just misguided. Although HE don't care if the local network jams up as long as their mainlines flow better.

That isn't how this is supposed to work.
5 lanes through the lights, or 2 + 1 freeflow - I know which I think will work better.
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Bryn666
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Re: M6 J10 Improvements

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Jeni wrote: Sun Mar 08, 2020 19:18
Bryn666 wrote: Sun Mar 08, 2020 19:13
Jeni wrote: Sun Mar 08, 2020 19:07

I wouldn't quite say "disgraceful" or "waste"
Just misguided. Although HE don't care if the local network jams up as long as their mainlines flow better.

That isn't how this is supposed to work.
5 lanes through the lights, or 2 + 1 freeflow - I know which I think will work better.
You're under the misapprehension that HE's consultants know how to configure roundabout signal timings. From experience they're not very good at it.

This scheme will massively disbenefit everything not already on the M6 - I'll bet good money on it.

You know how you hate being held on a commuter train so an intercity can zip past? This is what HE do with these junctions.
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Re: M6 J10 Improvements

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Bryn666 wrote: Sun Mar 08, 2020 19:21 You're under the misapprehension that HE's consultants know how to configure roundabout signal timings. From experience they're not very good at it.

This scheme will massively disbenefit everything not already on the M6 - I'll bet good money on it.

You know how you hate being held on a commuter train so an intercity can zip past? This is what HE do with these junctions.
Happy to buy a hat and eat it if I turn out to be wrong :-)
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Re: M6 J10 Improvements

Post by Steven »

Given that the biggest queues at the junction (ignoring the regularly stationary M6 beneath, for which there is no direct change) are A454 eastbound entry to the roundabout, I'm not convinced that this is the best way to spend money on the junction, and the difference over "do nothing" isn't enough to be worth the cost.
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jackal
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Re: M6 J10 Improvements

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Jeni wrote: Sun Mar 08, 2020 19:07
jackal wrote: Sun Mar 08, 2020 17:12 It really is a disgraceful waste of public money that they're removing the existing freeflow left turn.
I wouldn't quite say "disgraceful" or "waste"
Replacing a freeflow lane with two signalised lanes reduces capacity and increases congestion. So money is being spent to make things worse. Hence 'disgraceful waste of public money'.

The circulatory carriageway is also being made wider, which is an improvement of course, but should not be conflated with the distinct issue of the left turn.
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Re: M6 J10 Improvements

Post by Bryn666 »

jackal wrote: Mon Mar 09, 2020 09:31
Jeni wrote: Sun Mar 08, 2020 19:07
jackal wrote: Sun Mar 08, 2020 17:12 It really is a disgraceful waste of public money that they're removing the existing freeflow left turn.
I wouldn't quite say "disgraceful" or "waste"
Replacing a freeflow lane with two signalised lanes reduces capacity and increases congestion. So money is being spent to make things worse. Hence 'disgraceful waste of public money'.

The circulatory carriageway is also being made wider, which is an improvement of course, but should not be conflated with the distinct issue of the left turn.
Well, not always. If, hypothetically, a left turn lane can only process 2,500 veh per hour and a two lane signal approach can process 3,125 with the staging... it's a marginal benefit but it is still there.

The real issue is this is a massive amount of spend for little gain, the junction is still signalised, it just has wider approaches to the same bottleneck. Classic HE backwards thinking.
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Re: M6 J10 Improvements

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Bryn666 wrote: Mon Mar 09, 2020 10:55
jackal wrote: Mon Mar 09, 2020 09:31
Jeni wrote: Sun Mar 08, 2020 19:07

I wouldn't quite say "disgraceful" or "waste"
Replacing a freeflow lane with two signalised lanes reduces capacity and increases congestion. So money is being spent to make things worse. Hence 'disgraceful waste of public money'.

The circulatory carriageway is also being made wider, which is an improvement of course, but should not be conflated with the distinct issue of the left turn.
Well, not always. If, hypothetically, a left turn lane can only process 2,500 veh per hour and a two lane signal approach can process 3,125 with the staging... it's a marginal benefit but it is still there.

The real issue is this is a massive amount of spend for little gain, the junction is still signalised, it just has wider approaches to the same bottleneck. Classic HE backwards thinking.
That requires heroic assumptions about the amount of green time given to the left turn - the conflicting right turn off M6 sb is heavy. So as you say, hypothetical.

Tbf most of the expense of the scheme is on bridge replacement, and as they're old structures it's as much maintenance scheme as upgrade. It's just a shame that they've left obvious sources of congestion (e.g., the unnecessary B road connection) in place and faffed about with the freeflow lane when it works fine.
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Re: M6 J10 Improvements

Post by nick_dunn »

The M6 is due to be closed at J10 from 8pm Friday 2 July to 6am Monday 5 July to allow the beams to be lifted into place for the north bridge, with another closure later in the summer for the south bridge work. An 'up and over' diversion will be in place. I suspect the area will be an 'avoid at any cost'!
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Re: M6 J10 Improvements

Post by Big L »

Third time lucky, they managed to do the job this weekend. HE timelapse...

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Re: M6 J10 improvements

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Re: M6 J10 Improvements

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Two topics merged.
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Re: M6 J10 Improvements

Post by brummie_rob »

Next weekend closure is 24th September. Be interesting now it's not Summer holidays if the queues are as bad. There were delays of over 2 hours on the last closure.
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Re: M6 J10 Improvements

Post by Big L »

Noticed this evening that traffic is using the new bridge on the southern half of the roundabout. Lucky really as the Motorway is closed this weekend for the old bridge to be demolished.

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The local rag are reporting that the bridge being demolished is 150 years old!
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Peter Freeman
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Re: M6 J10 Improvements

Post by Peter Freeman »

Jeni wrote: Sun Mar 08, 2020 19:18 5 lanes through the lights, or 2 + 1 freeflow - I know which I think will work better.
I'm with Jeni on this one. While it's true that adding single-lane freeflow left turns is super-cost-effective for many roundabout issues, it's also true that the more lanes, the higher the throughput (subject to signal phasing). Freeflow isn't everything. To stop at a signal for a left turn, where virtually all the other movements have to stop for at least one signal, is not a great imposition. I assume the design process and modelling has shown a reason for it - perhaps pedestrian/NMU safety?
Bryn666 wrote: Sun Mar 08, 2020 19:21 This scheme will massively disbenefit everything not already on the M6 - I'll bet good money on it.
While the scheme is rubbish, I think it will benefit just about all users. This is the trouble with 'replace with the same inappropriate design, but bigger'. They're bound to help, but they ignore the underlying problem, which is (getting out his axe and his grinder) -

A roundabout is a wonderful intersection type, and is even a fairly good type of minor motorway interchange. But once you signalise it, it ceases to be a true roundabout, and it loses all the roundabout's good features. It becomes a signalised intersection with an illogical shape. There are many signalised intersection shapes, all of them better than a circle. This large site, since the powers-that-be have decided that the current structures have to go, would have suited most of the alternative shapes.

Anyway, too late now - I've watched the timelapse videos.
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Re: M6 J10 Improvements

Post by jackal »

Looking at the 2015 consultation brochure, it seems some consideration was given to a flyover, seemingly along the A454 in a stackabout-like configuration. It's called option 4.

The main objection concerns "conflicts between flyover traffic turning left onto Bloxwich Lane and eastbound straight ahead traffic along A454/Wolverhampton Road", but it seems this could have been resolved simply by restricting access from the flyover to Bloxwich Lane. There is also no consideration of an alternative flyover from the M6 southbound onto the Black Country Route.

Given options 1a, 1b, 2 and 3 were all signalised roundabouts, and option 5 (a hamburger) is a variant of the same approach, it seems they were pretty committed to that kind of design.

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Re: M6 J10 Improvements

Post by Truvelo »

What seems to have scuppered any sort of additional freeflow movement is the recent hotel/services development to the southeast of the junction. Many years ago I drew this which favours freeflow movements between the M6 and Black Country Route which is no longer possible due to said development. I'm not sure of the merits of a simple flyover unless traffic levels using A454 to A454 are higher than I realise.
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Re: M6 J10 Improvements

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Truvelo wrote: Sat May 07, 2022 22:59 I'm not sure of the merits of a simple flyover unless traffic levels using A454 to A454 are higher than I realise.
https://www.sabre-roads.org.uk/wiki/ind ... _23379.jpg
They probably are. Remember that M6 J10 is literally on the functional area boundary of Wolverhampton and Walsall, meaning that the largest economic "pulls" are east-west and not north-south.
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Re: M6 J10 Improvements

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jackal wrote: Sat May 07, 2022 12:39 Looking at the 2015 consultation brochure, it seems some consideration was given to a flyover, seemingly along the A454 in a stackabout-like configuration. It's called option 4.
The Black Country Route is a nice-looking road, with the first few miles west of M6 being HQDC. However, it's not a long-distance expressway. It has a series of traffic signal junctions only 1 mile east of here, which appear (from GM's typical traffic display) to be not seriously congested. Therefore, freeflow to the M6 is not essential. Truvelo's design was nice, but virtually impossible to justify.

I expect that A454 traffic approaching J10 from either direction is likely to be turning onto the M6. For that reason, I think a DDI (which can only sustain a 50% duty cycle for straight-through traffic, but favours turns) would have suited. It should have had multi-lane turns (see good examples in the USA). Its two bridges could have been constructed within the current circular carriageway with little disruption. The resulting highly capable DDI would have fitted easily on this site.

The B-Road should be stopped up (or perhaps LI-LO'd with the northbound on-ramp!). It has adequate connections further back, to the west.
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Re: M6 J10 Improvements

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Peter Freeman wrote: Sun May 08, 2022 09:16 I expect that A454 traffic approaching J10 from either direction is likely to be turning onto the M6.
Why do you expect that? The travel-to-work data in the area (as well as local experience) suggests otherwise.
The B-Road should be stopped up (or perhaps LI-LO'd with the northbound on-ramp!). It has adequate connections further back, to the west.
It is a bus only route westbound for all traffic leaving the roundabout, though access to the hotel to the NW of the junction is also available. I can see continued value in bus and NMU traffic for the area to the west.

There is no adequade eastbound connection further west for bus and NMU traffic; although through traffic for other traffic classes could be diverted via Bentley Road North.
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Re: M6 J10 Improvements

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