M25 junction 28 improvements

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qwertyK
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A12/M25 Brook Street J28 remodelling scheme

Post by qwertyK »

Looks like the problems at A12 J11/M25 J28 may come to an end. More news on the improvements. Apparently there is options for a new link road and a cloverleaf junction. Public consultations taking place in Harold Hill and Brentwood in coming weeks.

Here's the full story
http://www.essexlive.news/100m-investme ... story.html
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jackal
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Re: A12/M25 Brook Street J28 remodelling scheme

Post by jackal »

There's already a thread about this:

http://www.sabre-roads.org.uk/forum/vie ... =1&t=36781

Also a comment from the story linked in the OP:
Highways England: the options shown here are redundant. We are currently consulting on three different options as per the brochure on the web site: https://highwaysengland.citizenspace.co ... ochure.pdf
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jackal
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Re: M25 junction 28 improvements

Post by jackal »

This story linked by KwertyQ shows some interesting earlier designs for the junction, including the following:
M25 A12.jpg
It appears to show the loop as per 5B (the first of the consultation options) with an additional freeflow right turn for A12wb->M25nb, and an improved freeflow left turn for M25sb->A12eb. This would be an excellent further upgrade for the junction which will hopefully be compatible with the selected option.
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Truvelo
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Re: M25 junction 28 improvements

Post by Truvelo »

The article refers to it as a cloverleaf. Maybe there will eventually be a loop for all the right turns :pig:
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Glom
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Re: M25 junction 28 improvements

Post by Glom »

One loop is a cloverleaf, because it looks like a leaf of a clover.
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jackal
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Re: M25 junction 28 improvements

Post by jackal »

Glom wrote:One loop is a cloverleaf, because it looks like a leaf of a clover.
In a roads context cloverleaf is pretty universally used to refer to a grade-separated interchange with four loops. It does not refer to a single loop.
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Bryn666
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Re: M25 junction 28 improvements

Post by Bryn666 »

Indeed, a single loop is a, err, loop.
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WHBM
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Re: M25 junction 28 improvements

Post by WHBM »

I thought 270-degree loops were now out of favour because of their liability to overturning accidents with HGVs.
Runwell
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Re: M25 junction 28 improvements

Post by Runwell »

WHBM wrote:It doesn't seem to do anything for the A12 westbound onto the roundabout problem, which by my experience is the worst issue here. A lot of knowledgeable traffic apparently diverts now from the Dartford Tunnels by the recently improved A13 and A130 to Chelmsford (it's freeflow between these two junctions), yet this is the flow relieved by the sole loop proposed for this junction.
Trouble is the stretch up to Chelmsford, and heading down to the A127, are now a big source of congestion, at both ends of the day, so I wonder how viable that is now as an alternative?

I can't see any improvement to the A130/A12 junction until the A12 is widened around Chelmsford. There are now plans for the A127/A1245 junction, to build a new access road from the A130 s/b to the e/b A127, and later on widening the roundabout under the A127, but both of these plans are some way off.
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jackal
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Re: M25 junction 28 improvements

Post by jackal »

Runwell wrote: There are now plans for the A127/A1245 junction, to build a new access road from the A130 s/b to the e/b A127, and later on widening the roundabout under the A127, but both of these plans are some way off.
Thanks for that, I've made a new thread about it:
http://www.sabre-roads.org.uk/forum/vie ... =1&t=36822
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jackal
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Re: M25 junction 28 improvements

Post by jackal »

A few details in this article. Interestingly, the project manager Piotr Grabowiecki commented:
In [option] 5B we can add additional cloverleaves around the junction but to improve the actual capacity of the link we would have to remove it and provide something else
I think we may have found the origin of the loop=cloverleaf terminology :) If you want an additional 'cloverleaf', I've got just the ticket...
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M25 J28.png
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Bryn666
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Re: M25 junction 28 improvements

Post by Bryn666 »

I'm going to nickname that 'Swirly McSwirlington' :lol:

Loops are still in vogue, given the A556/A50 junction has one.
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Glom
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Re: M25 junction 28 improvements

Post by Glom »

Given where that loop is going and the structures needed, wouldn't it just be easier in that case to make it semi-directional?
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Re: M25 junction 28 improvements

Post by Chris5156 »

Glom wrote:Given where that loop is going and the structures needed, wouldn't it just be easier in that case to make it semi-directional?
If you're referring to Jackal's second loop from A12 westbound to M25 northbound, I think you'd need so much regrading of the existing A12 that it would be difficult to phase construction and probably more expensive than would make it economical. Whereas building a bridge crossing the A12, and moving the sliproad offline, is easier and therefore a bit cheaper to build.
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Gav
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Re: M25 junction 28 improvements

Post by Gav »

Instead of piecemeal slip road additions....

1. remove M25 access to the roundabout - doing this would cut down a significant amount of traffic.

2. Install two trumpet style interchanges to the M25 and A12 with required link road. No stop lights and total freeflow between M25 and A12
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jackal
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Re: M25 junction 28 improvements

Post by jackal »

Glom wrote:Given where that loop is going and the structures needed, wouldn't it just be easier in that case to make it semi-directional?
I drew that before I'd seen this rejected plan:
M25 A12.jpg
It's basically what you're describing, though the A12wb->M25nb turn is more 'cyclic' (like a windmill/octopus) than a classic stack-style semi-direct ramp.

As Chris says, providing a turn like that is more expensive than providing another loop, but it's a higher quality connection so might be worth it.
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Re: M25 junction 28 improvements

Post by Glom »

I was thinking something like that rather than something crossing the centre of junction although that Westbound onslip would be realigned to go round rather than over the cyclic slip.
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jackal
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Re: M25 junction 28 improvements

Post by jackal »

Here's a fantasy layout based on the aforementioned rejected design, but with two extra freeflow right turns to make it a full freeflow effort. It uses an additional six bridges compared to the status quo. The new right turns use much of the existing roundabout so the A1023 and services get disconnected... as I say, very much a fantasy design :) Mostly I was just interested in how easy it would be to upgrade a stackabout using this sort of design.
M25 A12.jpg
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sotonsteve
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Re: M25 junction 28 improvements

Post by sotonsteve »

What are the A12 (to/from Essex) to/from M25 traffic flows like compared with the A12 straight through the junction in towards London? As a three level stacked roundabout, could it be configured such that instead of having the A12 grade separated beneath the interchange that this bit of road is used for the M25 slip roads, and A12 through traffic routed up and round the roundabout, a bit like so?
A12 M25.jpg
poleman
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Re: M25 junction 28 improvements

Post by poleman »

All of these suggestions look great, and better than what is on the table with the consultation. It just seems such a tease. ...this is what you could've had!

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