M11, New Junction 7a

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doebag
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Re: M11, New Junction 7a

Post by doebag »

Highways England twitter feed states this weekends closure is for postitioning of bridge beams. So things are progressing.
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Re: M11, New Junction 7a

Post by Peter Freeman »

The God of Biscuits wrote: Tue Feb 23, 2021 14:48One thing I don't really get about the scheme is the design of the motorway junction itself. Fair enough that it doesn't warrant anything trumpet-like with free-flow in all directions, but why isn't the roundabout on the eastern side of the motorway a teardrop? - it only connects to slip roads on that side... And why is the overbridge marked out with two lanes eastbound? - the southbound on slip (which is the only place those lanes are going) only has one lane...
The two-lane eastbound width is beneficial, even though that traffic subsequently gets compressed on the southbound on-slip: it allows platoons of eastbound vehicles to enter and vacate the roundabout more quickly. This in turn provides more opportunity for vehicles on the southbound off-slip to enter the roundabout and head west over the bridge. It addresses one of the minor problems with dumbbell interchanges: a lack of gap-forming conflicts. At a normal roundabout, opportunities/gaps for you to enter are created by vehicles leaving at an exit on your right.
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c2R
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Re: M11, New Junction 7a

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I may be proved wrong, but I'm still not convinced that the interchange is going to be anywhere near sufficient capacity once the A414 is plugged in, Harlow North is built, and a tonne of new development land is opened up to the east of the M11...
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Chris5156
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Re: M11, New Junction 7a

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c2R wrote: Sun Jun 06, 2021 23:45I may be proved wrong, but I'm still not convinced that the interchange is going to be anywhere near sufficient capacity once the A414 is plugged in, Harlow North is built, and a tonne of new development land is opened up to the east of the M11...
But it's got two roundabouts! Everyone knows that, to add capacity to a junction, you build more roundabouts. And if that still isn't enough capacity it can all then be signalised, resulting in a traffic light controlled junction on a layout that isn't optimal for signalisation. As far as I'm aware there is no better or more efficient way to build a three-way junction between two major roads with significant volumes of turning traffic. If there was, surely someone would have thought of it by now.

Yours sincerely,

Archibald Shortsighted
President, Chartered Institute of Building Signalised Roundabouts Everywhere and Then Wondering Why The Traffic Is Awful
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c2R
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Re: M11, New Junction 7a

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Chris5156 wrote: Mon Jun 07, 2021 10:51
c2R wrote: Sun Jun 06, 2021 23:45I may be proved wrong, but I'm still not convinced that the interchange is going to be anywhere near sufficient capacity once the A414 is plugged in, Harlow North is built, and a tonne of new development land is opened up to the east of the M11...
But it's got two roundabouts! Everyone knows that, to add capacity to a junction, you build more roundabouts. And if that still isn't enough capacity it can all then be signalised, resulting in a traffic light controlled junction on a layout that isn't optimal for signalisation. As far as I'm aware there is no better or more efficient way to build a three-way junction between two major roads with significant volumes of turning traffic. If there was, surely someone would have thought of it by now.

Yours sincerely,

Archibald Shortsighted
President, Chartered Institute of Building Signalised Roundabouts Everywhere and Then Wondering Why The Traffic Is Awful
Quite. The M1 J13 or A1(M) at Olding's Corner tell you everything you could possibly ever need to know about using such a layout where traffic is busy.... this is the sort of junction that's fine if you've got a rural D2 with a junction to serve a couple of villages; not something that you might put in place to serve a new town and a strategic east-west corridor that's within spitting distance of the M25.

In other news, the link road will be numbered and a section of the B183 (Gilden Way) renumbered A1025, according to a public notice here: https://web.archive.org/web/20210607094 ... rder_2019/
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Re: M11, New Junction 7a

Post by Peter Freeman »

Fortunately, Archibald, it's not a '2-bridger' with curved bridges. As long as the tin-sheds don't encroach too closely, the single straight 4-lane bridge lends itself to future conversion to a well-designed and well-signalised diamond. Standard layout, or DDI preferably, or SPUI even more preferably if you can stretch to widening the bridge a bit.
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Re: M11, New Junction 7a

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Peter Freeman wrote: Mon Jun 07, 2021 11:09 Fortunately, Archibald, it's not a '2-bridger' with curved bridges. As long as the tin-sheds don't encroach too closely, the single straight 4-lane bridge lends itself to future conversion to a well-designed and well-signalised diamond. Standard layout, or DDI preferably, or SPUI even more preferably if you can stretch to widening the bridge a bit.
Perhaps you're right, if it was just coping with some additional new development around the site, but that's not the eventual idea...

There's a significant amount of suppressed demand and traffic that presently uses A10/M25/M11 to head towards London that will re-route when the Harlow northern bypass is eventually built. There's also a massive new town being planned for North of Harlow, as well as development land opened up by this to the East. Finally, there's likely to be re-routing of local traffic to junction hop from Harlow to Stortford on the M11 rather than the current slog through Sawbridgeworth. This is the sort of thing that should have been at least a massive single roundabout interchange from the off, given what's planned, with potential space reserved to add additional free flow links from M11 north to A414.
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Re: M11, New Junction 7a

Post by Peter Freeman »

The problem with M1 J13 is not that it's a dumbbell - it's all the other ridiculous bits.
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Re: M11, New Junction 7a

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Yes... but that's what is being set up to be built here as well... a regionally strategic east west route meets a nationally strategic north south route, with access to a load of new houses and additional development land.
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Re: M11, New Junction 7a

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Peter Freeman wrote: Mon Jun 07, 2021 11:09 Fortunately, Archibald, it's not a '2-bridger' with curved bridges. As long as the tin-sheds don't encroach too closely, the single straight 4-lane bridge lends itself to future conversion to a well-designed and well-signalised diamond. Standard layout, or DDI preferably, or SPUI even more preferably if you can stretch to widening the bridge a bit.
I'll pass on your message, of course, but what was really required here was a perfectly simple free-flowing design. A trumpet would not have been too much to ask and would have been perfectly feasible. It is supposed to eventually form the terminus of a grade-separated expressway, continuing the A414 around the north side of Harlow. There's no reason why all the conflict points of a dumbbell, a diamond, a SPUI, a DDI needed to be introduced at all.

Even so - this dumbbell will never be converted to a well designed signalised diamond, or a DDI, or a SPUI, because such things don't happen here. We build roundabouts, and signalise them in ever more inventive ways, and wonder why it isn't working. M11 J7a won't be an exception.
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Re: M11, New Junction 7a

Post by Bryn666 »

Chris5156 wrote: Mon Jun 07, 2021 11:56
Peter Freeman wrote: Mon Jun 07, 2021 11:09 Fortunately, Archibald, it's not a '2-bridger' with curved bridges. As long as the tin-sheds don't encroach too closely, the single straight 4-lane bridge lends itself to future conversion to a well-designed and well-signalised diamond. Standard layout, or DDI preferably, or SPUI even more preferably if you can stretch to widening the bridge a bit.
I'll pass on your message, of course, but what was really required here was a perfectly simple free-flowing design. A trumpet would not have been too much to ask and would have been perfectly feasible. It is supposed to eventually form the terminus of a grade-separated expressway, continuing the A414 around the north side of Harlow. There's no reason why all the conflict points of a dumbbell, a diamond, a SPUI, a DDI needed to be introduced at all.

Even so - this dumbbell will never be converted to a well designed signalised diamond, or a DDI, or a SPUI, because such things don't happen here. We build roundabouts, and signalise them in ever more inventive ways, and wonder why it isn't working. M11 J7a won't be an exception.
I think my views are well known on this subject. [proceeds to rant about it anyway]
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Re: M11, New Junction 7a

Post by c2R »

This study has some of the evidence to back up the general shift in movements to this new route, once the Harlow northern bypass is complete: https://www.efdclocalplan.org/wp-conten ... esting.pdf - p14
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Re: M11, New Junction 7a

Post by The God of Biscuits »

Peter Freeman wrote: Sun Jun 06, 2021 01:25
The God of Biscuits wrote: Tue Feb 23, 2021 14:48One thing I don't really get about the scheme is the design of the motorway junction itself. Fair enough that it doesn't warrant anything trumpet-like with free-flow in all directions, but why isn't the roundabout on the eastern side of the motorway a teardrop? - it only connects to slip roads on that side... And why is the overbridge marked out with two lanes eastbound? - the southbound on slip (which is the only place those lanes are going) only has one lane...
The two-lane eastbound width is beneficial, even though that traffic subsequently gets compressed on the southbound on-slip: it allows platoons of eastbound vehicles to enter and vacate the roundabout more quickly. This in turn provides more opportunity for vehicles on the southbound off-slip to enter the roundabout and head west over the bridge. It addresses one of the minor problems with dumbbell interchanges: a lack of gap-forming conflicts. At a normal roundabout, opportunities/gaps for you to enter are created by vehicles leaving at an exit on your right.
Here's the thing - everything you've said is entirely reasonable if traffic can be 'compressed' on the southbound on-slip, but this would require that, at the very least, it was two lanes wide at the roundabout exit with a merge further down the slip, a layout which is encountered quite frequently and generally works quite well. But the proposed layout on the Essex Highways website clearly shows the the southbound on-slip is one lane wide for its entire length, so it's not clear to me how this 'compression' is going to happen in a safe and orderly manner. It's surely the sort of thing that can be quite easily solved with changes to the road markings on the on-slip by removing some of the hard shoulder (plus hopefully some very clear signage on the eastbound approach to the new junction that both lanes should be used to go south), but the currently proposed layout seems to me to be an open invitation for some potentially very poor driving, and this is in a part of the world where members of the German Car Owner's Club generally don't even need the invitation... :twisted:
c2R wrote: Sun Jun 06, 2021 23:45 I may be proved wrong, but I'm still not convinced that the interchange is going to be anywhere near sufficient capacity once the A414 is plugged in, Harlow North is built, and a tonne of new development land is opened up to the east of the M11...
I think that the layout of the southbound off-slip (a parallel diverge with tiger tails) suggests that the designers are expecting it to be busy even before then...
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Re: M11, New Junction 7a

Post by Big Nick »

The works on this are progressing well. I drove past in both directions today and the overbridge is in place and in use by the workforce. The sliproads are also in place along with some barriers on the north side.
Oddly it was a 50 limit going north but a 60 limit going south. :?
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Re: M11, New Junction 7a

Post by yen_powell »

It was 60 in both directions last week, the average speed cameras had gone a little while back though so everyone was ignoring that. I came home tonight and there is now a 50mph limit northbound and new average speed cameras up. These ones are rear number plate facing unlike the previous 60mph ones so I have to be careful on my bike.
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Re: M11, New Junction 7a

Post by doebag »

yen_powell wrote: Fri Dec 17, 2021 22:49 It was 60 in both directions last week, the average speed cameras had gone a little while back though so everyone was ignoring that. I came home tonight and there is now a 50mph limit northbound and new average speed cameras up. These ones are rear number plate facing unlike the previous 60mph ones so I have to be careful on my bike.
N/B Lane 3 is sub standard width, S/B all lanes are now normal width .
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Re: M11, New Junction 7a

Post by trickstat »

Big Nick wrote: Fri Dec 17, 2021 18:27 The works on this are progressing well. I drove past in both directions today and the overbridge is in place and in use by the workforce. The sliproads are also in place along with some barriers on the north side.
Oddly it was a 50 limit going north but a 60 limit going south. :?
The former is uphill as can be seen on maps! :wink:
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Re: M11, New Junction 7a

Post by Runwell »

doebag wrote: Fri Dec 17, 2021 23:38
yen_powell wrote: Fri Dec 17, 2021 22:49 It was 60 in both directions last week, the average speed cameras had gone a little while back though so everyone was ignoring that. I came home tonight and there is now a 50mph limit northbound and new average speed cameras up. These ones are rear number plate facing unlike the previous 60mph ones so I have to be careful on my bike.
N/B Lane 3 is sub standard width, S/B all lanes are now normal width .
I'm sure when I went through northbound last weekend, when it was still at 60, they'd removed the narrow lanes? Did they remove them, only to put them back in again? I was in lane 1 pretty much the whole way last Saturday, as it was pretty quiet despite some unpleasant driving weather, so I may just have missed them, but I seem to recall there not being that many signs for the works all of a sudden?
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Re: M11, New Junction 7a

Post by doebag »

Runwell wrote: Sun Dec 19, 2021 01:19

I'm sure when I went through northbound last weekend, when it was still at 60, they'd removed the narrow lanes? Did they remove them, only to put them back in again? I was in lane 1 pretty much the whole way last Saturday, as it was pretty quiet despite some unpleasant driving weather, so I may just have missed them, but I seem to recall there not being that many signs for the works all of a sudden?
I came through Tuesday evening . Lane 3 is/was narrow.
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Re: M11, New Junction 7a

Post by hoopdog »

Some new signage is now up at the new hamburger junction at Churchgate Street, looks like Gilden Way is going to be the A1025 from the A414 to J7a. This number is already in use in the town for Second and Third Avenues.
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