M4 Junction 3 to 12 Smart Motorway

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EpicChef
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Re: M4 Junction 3 to 12 Smart Motorway

Post by EpicChef »

And I really think there should have been continuous lighting like there was earlier.

There will no longer be lighting between J5-8/9.
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Re: M4 Junction 3 to 12 Smart Motorway

Post by owen b »

Chris5156 wrote: Fri Oct 08, 2021 09:11
Peter Freeman wrote: Fri Oct 08, 2021 01:05
Chris5156 wrote: Thu Oct 07, 2021 18:45
And designed that way in case of traffic queueing back onto the mainline from the roundabout, not by looking at the requirements of predicted traffic flows. Or even current traffic flows, come to that.
That's the thing that struck me too. Slip road traffic queuing back from the junction onto the mainline is best addressed by action at the junction; or, at the very least, by action on the slip road. But no - instead, let's allow the queue to form on lane 1, effectively a very long and possibly dangerous slip road, and compromise the capacity and fundamental effectiveness of our improvement scheme by dropping the lane from the mainline.
We have a history of this in the UK. The last tranche of motorway widening schemes, before Smart Motorways became the done thing, were on the M1, J6a-10 and 25-28. Both added a fourth lane but neither included any junction improvements beyond changes that were necessary to accommodate the new lane. This was despite several junctions along the way being overloaded. The reason for this, as stated at the time, was to “lock in” the benefits of the fourth lane by providing no new capacity to enter or exit the motorway, presumably in the misguided hope that traffic levels on the motorway would remain static. It didn’t work, naturally, and congestion at the junctions is worse than it was before.
In the case of M1 J6a-10 the plan was that one lane each way of the widened motorway would become HOV (high occupancy vehicle) lanes, this plan being dropped only after the widening work had started : http://news.bbc.co.uk/1/hi/england/beds ... 312650.stm This was also part of the plan to "lock in" the benefits of the widening by suppressing demand growth.
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Re: M4 Junction 3 to 12 Smart Motorway

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What about converting M1 J6A-10 into D5 ALR and having lane 4 as HOV?
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Re: M4 Junction 3 to 12 Smart Motorway

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EpicChef wrote: Fri Oct 08, 2021 22:06 What about converting M1 J6A-10 into D5 ALR and having lane 4 as HOV?
Either you mean lane 5 or that would be massively problematic!
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Re: M4 Junction 3 to 12 Smart Motorway

Post by mathmo »

Junctions 8/9-12 is now almost fully open with four lanes at 60mph (signed using VMS, not temporary signs). The project newsletter says it will be open at 70mph later this year.
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Re: M4 Junction 3 to 12 Smart Motorway

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Herned wrote: Fri Oct 08, 2021 23:48
EpicChef wrote: Fri Oct 08, 2021 22:06 What about converting M1 J6A-10 into D5 ALR and having lane 4 as HOV?
Either you mean lane 5 or that would be massively problematic!
I do mean lane 5!
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Re: M4 Junction 3 to 12 Smart Motorway

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mathmo wrote: Sat Oct 09, 2021 11:09 Junctions 8/9-12 is now almost fully open with four lanes at 60mph (signed using VMS, not temporary signs). The project newsletter says it will be open at 70mph later this year.
I guess they're assuming they'll get ministerial approval despite the fact that nobody knows at this moment whether their SVD solution isn't working.
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Re: M4 Junction 3 to 12 Smart Motorway

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EpicChef wrote: Fri Oct 08, 2021 22:06 What about converting M1 J6A-10 into D5 ALR and having lane 4 as HOV?
HOV seems to have been pretty much abandoned. It only really makes sense when the non-HOV lanes are chronically congested, as in LA, so perhaps the logic is that you shouldn't design in congestion.

In any case M1 J6a-10 D5ALR should be progressed. The M4 scheme is the trial run for that standard (J4 to J4b) so perhaps we'll see it rolled out more widely if it works out well. M25 J15-16 is next in line.
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Re: M4 Junction 3 to 12 Smart Motorway

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jackal wrote: Sat Oct 09, 2021 17:04In any case M1 J6a-10 D5ALR should be progressed. The M4 scheme is the trial run for that standard (J4 to J4b) so perhaps we'll see it rolled out more widely if it works out well. M25 J15-16 is next in line.
It says something about how overdue the widening of 6a-10 was a decade ago that D4M is already showing the strain.
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Re: M4 Junction 3 to 12 Smart Motorway

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Chris5156 wrote: Sat Oct 09, 2021 18:40
jackal wrote: Sat Oct 09, 2021 17:04In any case M1 J6a-10 D5ALR should be progressed. The M4 scheme is the trial run for that standard (J4 to J4b) so perhaps we'll see it rolled out more widely if it works out well. M25 J15-16 is next in line.
It says something about how overdue the widening of 6a-10 was a decade ago that D4M is already showing the strain.
And you seriously think that history won't repeat itself if it became D5ALR?

The fact the D4M has become so overloaded in such a short time is pretty damning evidence that all road widening does is attract more traffic!

There needs to be a sea change in Government polices starting with housing & business developments which stops making them so car dependent and provides LONG TERM, CENTRAL GOVERNMENT FUNDED public transport options and addressing congestion that way - not just adding ever more traffic lanes.

It also needs a roads strategy which is less about funnelling everything down a few mega arteries and instead encourages a bigger network of lower capacity roads the distributing traffic much more evenly and avoid the ridiculous situation that exists with the likes of the M25 where it is overloaded with traffic that should be orbiting much further out.

That of course won't happen, particularly under the current administration who don't care about anyone other than themselves and their developer / financier friends.
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Re: M4 Junction 3 to 12 Smart Motorway

Post by EpicChef »

jackal wrote: Sat Oct 09, 2021 17:04 In any case M1 J6a-10 D5ALR should be progressed. The M4 scheme is the trial run for that standard (J4 to J4b) so perhaps we'll see it rolled out more widely if it works out well. M25 J15-16 is next in line.
In a sudden stroke of wisdom, the Highways Agency (as it was then called) chose to widen M1 J6a-10 continuously, instead of 'rapid' widening, and reconstructed all the bridges over and under the motorway. There is already a concrete barrier, LED lighting, and VSL gantries.

It will be VERY easy to widen to D5ALR, and could be done within as little as 2 years, with 4 narrow lanes in each direction (3 during quiet times).

I feel this deserves a new thread, so I would encourage any further discussion about this to go there.
I'll create one.
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Re: M4 Junction 3 to 12 Smart Motorway

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DB617 wrote: Sat Oct 09, 2021 14:43
mathmo wrote: Sat Oct 09, 2021 11:09 Junctions 8/9-12 is now almost fully open with four lanes at 60mph (signed using VMS, not temporary signs). The project newsletter says it will be open at 70mph later this year.
I guess they're assuming they'll get ministerial approval despite the fact that nobody knows at this moment whether their SVD solution isn't working.
SVD is sound in principle and if we have been making incredibly accurate radar guided missiles for years I refuse to believe the technology isn't there to put it in place relatively quickly.

If ether are problems with SVD on Smart motorways its either because National Highways (for England) / Whatever other money wasting rebrand Boris wants to give it this week) cannot manage a **** up in a brewery / is completely devoid of engineering talent*, or its because they have tried to do it on the cheap (cheapest contractors, cheapest tech) or a combination of both!

* Instead favouring people who can design snazzy websites / produce glossy PDFs saying how wonderful the organisation is and lots of been counters.
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Re: M4 Junction 3 to 12 Smart Motorway

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WHBM wrote: Thu Oct 07, 2021 19:24 This change at J5 does explain why considerable works alongside the bridges started about four years ago, then were abandoned. I think I wrote about it here at the time.
In the original plans shown at the Examination in public, given all the new bridges required, it went through the Planning Inspectorate national Infrastructure process, the only lane drops were at the ends of the scheme and at J10 (A329(M)) and J4b (M25). Now they have appeared at J11, J8/9 and J5 and by look of the sign gantries, which are missing signs at J6 as well.

J6 bridges were strengthened and widened about 8 years ago, so now have a hard shoulder, so I am hoping my fears on J6 are wrong. But J5 is just unbelievably silly, given this was a bottleneck with 3 lanes.

But how come HE or now NH can go through consultation, the planning process and then change the design without any further consultation. And in addition why in the south the M4, M3 and M23 do not have ALR through junctions but M1 and M6 in the midlands and north do. Is it different offices with different experiences. By the ned four years of slogging along the M4 from Reading to town due to road works to be replaced with a shiny 4 lane ALR but still slogging it through the junctions. A wasted opportunity.
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Re: M4 Junction 3 to 12 Smart Motorway

Post by WHBM »

The initial works for the J5 at Langley bridge widening are still visibly in hand on Google Maps for April 2017

https://www.google.com/maps/@51.4916534 ... 312!8i6656
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Re: M4 Junction 3 to 12 Smart Motorway

Post by DB617 »

This weekend's Hungerford diversion was a little bit brutal. Long queues on the A34 towards J13 but we were heading west towards Bristol and the A338 really narrows down through the village, to the point where HGVs and coaches like ours were having to slow to a crawl to safely pass. Incidentally my coach took an extra hour and a half on the inbound journey from Bristol to pick us up from London. It's quite bemusing to me that a motorway-frequenting company like National Express would fail to adjust their timetables appropriately for diversions that are programmed months in advance, but alas, a 20:50 arrival in Bristol turned into a 23:30. By the time the coach actually arrived at Victoria there was a gentleman yelling and practically jumping out of the crowd to chastise the staff. Yikes.
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Re: M4 Junction 3 to 12 Smart Motorway

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A303Chris wrote: Tue Oct 12, 2021 14:00
WHBM wrote: Thu Oct 07, 2021 19:24 This change at J5 does explain why considerable works alongside the bridges started about four years ago, then were abandoned. I think I wrote about it here at the time.
But how come HE or now NH can go through consultation, the planning process and then change the design without any further consultation. And in addition why in the south the M4, M3 and M23 do not have ALR through junctions but M1 and M6 in the midlands and north do. Is it different offices with different experiences. By the ned four years of slogging along the M4 from Reading to town due to road works to be replaced with a shiny 4 lane ALR but still slogging it through the junctions. A wasted opportunity.
Because they don't NEED to!

As you noted the demolition and reconstruction of the bridges required the purchasing of additional land not in the ownership of HE / NH and as such triggered all sorts of statutory legal requirements (including public consolations) to happen.

Remarking the carriageway by contrast carries no legal obligations to consult.

As to why its been done - I have a suspicion its finally dawned on HE / NH that putting an extra lane on the motorway itself will do sod all to stop queues from the junctions extending all the way back up the slip road and onto the mainline at peak times.

This obviously presents a safety hazard and although it could be eased by extending the slips backwards and widening them to give more stacking space that would probably require works outside the highway boundary. That in turn means yet more legal hoops to jump through and is not deliverable under the current works, which seem to have been done on a 'do minimum' basis rather than take the need to rebuild all the bridges as an opportunity to undertake a more fundamental rebuild - perhaps adding CD lanes between 5 and 4B say...
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Re: M4 Junction 3 to 12 Smart Motorway

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Phil wrote: Sun Oct 10, 2021 22:37 The fact the D4M has become so overloaded in such a short time is pretty damning evidence that all road widening does is attract more traffic!
I know we've had this debate before, but... typically that demand *already* existed but was using less suitable routes instead.

For example, since the M3 J2-J4A ALR opened, traffic on the A30 is significantly reduced - it is now using the M3 as intended.
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Re: M4 Junction 3 to 12 Smart Motorway

Post by Micro The Maniac »

A303Chris wrote: Tue Oct 12, 2021 14:00 And in addition why in the south the M4, M3 and M23 do not have ALR through junctions but M1 and M6 in the midlands and north do.
Look at any of the motorways with through-junction running... especially those "traditional" ones.

Congestion is typically concentrated at the on-slip merge, where the on-slip and lane 1 have to fit into lane 1. This results in lane 1 frequently coming to a stop, with knock-on effects to other lanes.

With the M3 design, joining traffic joins in its own lane, thus the remaining through-junction carriageways remain free-flowing... my opinion is that, at least on the M3 (and most of the M25 - stand-fast J11 but there are constraints there) lane drops/gains work.

I accept that this logic only works when leaving and joining traffic is close to 1/n of the total traffic, and through traffic is (n-1)/n [where n is the total number of lanes before and after the lane drop/gain]... my guess is that the M1/M6 junctions have a lower ratio of leavers/joiners and through traffic?
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Re: M4 Junction 3 to 12 Smart Motorway

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The M1 and M6 are major intercity motorways, and commuter traffic generally only uses specific busy sections of the motorways in and near the cities. Between the cities, it is mostly long-distance strategic traffic that is using the road in its entirety (or most of the length). This means that most traffic at each junction will be through traffic, and that capacity of 4-lane TJR will be needed. There are still certain major junctions, such as M1 J32, where there are lane drops and gains.
The scheme is much better designed.

I am still a huge advocate for more lighting on ALR motorway stretches, at least before, through, and after junctions, if not continuous, but I feel like I'm on my own...
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Re: M4 Junction 3 to 12 Smart Motorway

Post by Big L »

Travelled through eastbound as far as the M25 this evening. All good as far as 8/9, 4 lanes and 60 on the VMS, 50 after with 3 lanes. Flowing mostly well.
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