M1 J6A-10 D5 ALR

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M1 J6A-10 D5 ALR

Post by ManomayLR »

This stretch frequently struggles even with 4 lanes.

But HA (as they were then called) widened the stretch properly, including widening all the bridges. And so now it's possible to upgrade to D5ALR quickly, maybe within the space of 2 years or so.

There are already concrete barriers, LED lighting, and VSL gantries, so not much to upgrade.
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Re: M1 J6A-10 D5 ALR

Post by Chris5156 »

If it were to happen it would be some years away from starting. The current J13-16 works are due to run until 2023 and will be followed by works to revisit 10-13 and convert that to ALR. I can’t see roadworks being allowed to take over 6a-10 again until those ones have finished.
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Re: M1 J6A-10 D5 ALR

Post by jackal »

Chris5156 wrote: Mon Oct 11, 2021 10:22 If it were to happen it would be some years away from starting. The current J13-16 works are due to run until 2023 and will be followed by works to revisit 10-13 and convert that to ALR. I can’t see roadworks being allowed to take over 6a-10 again until those ones have finished.
The DHS to ALR conversion is supposed to complete in 2023-24. D5 ALR would follow on quite nicely except that it's not an RIS2 scheme, nor even in the pipeline for RIS3. I agree though that it would be a cheap but effective upgrade and would like to see it in RIS3 were that possible.

Some numbers for 2019:

UK rank/Road/Junctions/Standard/HGVs/AADF
15 M1 11 11A D3DHS* 24975 168763
17 M1 8 9 D4M 20698 166400
18 M1 7 8 D4M+D3 17563 166213
21 M1 6A 7 D4M 18249 163886
28 M1 9 10 D4M 18748 160373
30 M1 11A 12 D4ALR 22532 159866
50 M1 10 11 D3DHS* 21005 149909
51 M1 23A 24 D4M 20078 149587
70 M1 12 13 D3DHS* 21151 143195
87 M1 10 10 D4M 16414 137538
101 M1 11 11 D4ALR 18259 134930
*Scheduled for upgrade

If J6A-10 D5 ALR were progressed you'd hope some relief for J11-11A would also be on the cards, such as extension of the proposed Luton Northern bypass across to the A505. Currently J11-J11A is part of the east-west route, which it really shouldn't be.
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Re: M1 J6A-10 D5 ALR

Post by owen b »

jackal wrote: Mon Oct 11, 2021 11:45 If J6A-10 D5 ALR were progressed you'd hope some relief for J11-11A would also be on the cards, such as extension of the proposed Luton Northern bypass across to the A505. Currently J11-J11A is part of the east-west route, which it really shouldn't be.
I accept your logic, but the reality is that the Luton Northern Bypass is a dire local authority development route scheme with no meaningful compatibility with any plausible future improvements or extensions to make it part of a viable east-west route.
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Re: M1 J6A-10 D5 ALR

Post by jackal »

owen b wrote: Mon Oct 11, 2021 19:04
jackal wrote: Mon Oct 11, 2021 11:45 If J6A-10 D5 ALR were progressed you'd hope some relief for J11-11A would also be on the cards, such as extension of the proposed Luton Northern bypass across to the A505. Currently J11-J11A is part of the east-west route, which it really shouldn't be.
I accept your logic, but the reality is that the Luton Northern Bypass is a dire local authority development route scheme with no meaningful compatibility with any plausible future improvements or extensions to make it part of a viable east-west route.
Surely they could just extend from the eastern end of the proposed scheme. An S2 bypass is still a bypass, and a lot better than slogging through Luton.

It also would not be difficult to upgrade to D2 - the only significant structure will be D2 from the off.
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Re: M1 J6A-10 D5 ALR

Post by owen b »

jackal wrote: Mon Oct 11, 2021 19:36
owen b wrote: Mon Oct 11, 2021 19:04
jackal wrote: Mon Oct 11, 2021 11:45 If J6A-10 D5 ALR were progressed you'd hope some relief for J11-11A would also be on the cards, such as extension of the proposed Luton Northern bypass across to the A505. Currently J11-J11A is part of the east-west route, which it really shouldn't be.
I accept your logic, but the reality is that the Luton Northern Bypass is a dire local authority development route scheme with no meaningful compatibility with any plausible future improvements or extensions to make it part of a viable east-west route.
Surely they could just extend from the eastern end of the proposed scheme. An S2 bypass is still a bypass, and a lot better than slogging through Luton.

It also would not be difficult to upgrade to D2 - the only significant structure will be D2 from the off.
The missing link from the A6 north of Luton to the A505 north east of Luton is not so simple as it looks. It's an Area of Outstanding Natural Beauty. It's green belt. There's all sorts of archaeological stuff of interest. It goes across the Icknield Way. There's a golf course in the way and a couple of hills which are prominent on the skyline for miles around. There's a steep and very attractive chalk scarp slope with characteristic sensitive flora. There's various route permutations with different pros and cons, inner routes favouring congestion relief in the local area, outer routes being better for longer distance east - west through traffic. Previous proposals have been very controversial, very expensive, not very persuasive and have involved tunnels and lots of earthworks, for example the consultation I commented on in 2009 here : viewtopic.php?f=1&t=1674&start=42 (and various other posts around about that time in that thread).

I think it's quite obvious now (maybe it wasn't 10-15 years ago) that if there ever is a major east-west road link (and I very much doubt there will be) it will be on the M1 J13 to Oxford axis, rather than in the Stansted /Stevenage / M1 J11a / Aylesbury / M40 corridor. So I think any idea of a Luton northern bypass forming part of a major east - west strategic road is for the birds. But just building a crappy S2 from M1 J11a to the A6 north of Luton is pretty hopeless from Luton's perspective. It will result in another chunk of green belt being devoured on the Central Beds side of Luton and it will exacerbate already bad congestion in Luton on the A6, A5228 and A505 on the north and north east side of Luton.
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Re: M1 J6A-10 D5 ALR

Post by Patrick Harper »

Making a case for a D5 ALR of M1 J6a—J10 (and M25 J10—16) in the name of safety would be much harder as that section already has a lot of the tech that post 2013 ALR motorways employ to vary traffic restrictions when necessary, so the difference would be marginal. It would be a scheme solely in pursuit of extra capacity on the cheap, and that's harder to justify the cost of doing in the current climate.
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Re: M1 J6A-10 D5 ALR

Post by jervi »

I don't mind ALR, however 5 lanes with no shoulder I think is pushing the limits a little too far at the moment. Give it a few decades when automated driving takes over it may be appropriate, but not at the moment.
5 lanes even with a shoulder is still questionable, and there's a reason with DMRB doesn't allow it. Is the M1 between J6A and J10 was ever to be widened again, I'd imagine it to be a D4M+D2ALR as C/D carriageways.

Upgrading and improving the A1 to a motorway south of Huntingdon (along with A1(M) upgrades) would likely be a better solution to reduce traffic and congestion on the M1.
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Re: M1 J6A-10 D5 ALR

Post by Peter Freeman »

jervi wrote: Mon Oct 11, 2021 23:51 5 lanes even with a shoulder is still questionable, and there's a reason with DMRB doesn't allow it.
And the reason is?
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Re: M1 J6A-10 D5 ALR

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jervi wrote: Mon Oct 11, 2021 23:51 Upgrading and improving the A1 to a motorway south of Huntingdon (along with A1(M) upgrades) would likely be a better solution to reduce traffic and congestion on the M1.
Well of course it's "better" as in would deliver more of an improvement, but it would also cost ~10 times as much, not to mention being vastly more environmentally destructive. The choice is realistically between the ALR and the status quo.
Patrick Harper wrote: Mon Oct 11, 2021 22:22 Making a case for a D5 ALR of M1 J6a—J10 (and M25 J10—16) in the name of safety would be much harder as that section already has a lot of the tech that post 2013 ALR motorways employ to vary traffic restrictions when necessary, so the difference would be marginal. It would be a scheme solely in pursuit of extra capacity on the cheap, and that's harder to justify the cost of doing in the current climate.
This is a good point, though increasing capacity does of course increase safety on a currently congested road. The question is whether that gain outweighs the loss of the HS in safety terms, and if so, by how much.
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Re: M1 J6A-10 D5 ALR

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Peter Freeman wrote: Tue Oct 12, 2021 02:40
jervi wrote: Mon Oct 11, 2021 23:51 5 lanes even with a shoulder is still questionable, and there's a reason with DMRB doesn't allow it.
And the reason is?
Lane discipline breaks down on any carriageway wider than 3 lanes, the reason DMRB states a maximum of 4 lanes is because the capacity gains are still beneficial despite flow disruption from people sticking in the wrong lane for their chosen speed (e.g. 55 in lane 3 in free-flowing conditions).

The only places on the UK motorway network where carriageways are wider than 4 lanes are also places where queues happen to be some of the worst because the reason there's more than 4 lanes is to cope with weaving between junctions. Plantation Interchange on the M8 is a very early example of dividing weaving flows up into C/D lanes and it works relatively well. M25 J10-16 on the other hand is a complete bin fire.

In the USA, where "pick a lane and stay in it" and "overtake on any side" are standard rules then flow and discipline breakdown doesn't become a factor, but then the KSI rate per billion vehicle km on US freeways is higher than ours which suggests it isn't a good way to do things.
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Re: M1 J6A-10 D5 ALR

Post by Peter Freeman »

Bryn666 wrote: Tue Oct 12, 2021 09:49 In the USA, where "pick a lane and stay in it" and "overtake on any side" are standard rules then flow and discipline breakdown doesn't become a factor, but then the KSI rate per billion vehicle km on US freeways is higher than ours which suggests it isn't a good way to do things.
The reason I disputed the 'DMRB reason' statement is that in AU we do have a significant number of roads with >3 lanes per carriageway, and my observation is firmly that they do proportionally increase capacity as intended. Perhaps it is, as you suggest, owing to our freedom to overtake on either side, as in the USA. By the way, our practise is not "pick a lane and stay in it", but there is indeed more latitude to select a lane by destination, traffic density, distance to intended exit, upcoming-but-still-far-away lane drop, etc.

The UK's (and Norway's and Sweden's) KSI is enviably low. Ours is about double, like most of Western Europe and Canada. The US rate is double again. However, I don't think these differences are related much to carriageway widths or to lane protocols. I think they're related more to societal attitudes (esp. in the USA case), road law and its enforcement, and vehicle standards. (note to self: look more deeply into WHO country-comparison statistics).

Back on the >3 lanes topic (and sorry, I'm already OT for the thread), my belief is that (in the UK) >3 lanes might not provide proportionally increased capacity under normal traffic, but it will under congestion. In that situation, your traffic becomes rather like ours: speed-differential laminar flow disappears. And after all, widening is mainly to address congestion isn't it?

BTW, as we discussed not long ago in other threads, M25 J14-15-16 is terrible simply because it was very poor (simplistic) design. Is the J10-14 widening really a waste though?
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Re: M1 J6A-10 D5 ALR

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Peter Freeman wrote: Tue Oct 12, 2021 11:45
Bryn666 wrote: Tue Oct 12, 2021 09:49 In the USA, where "pick a lane and stay in it" and "overtake on any side" are standard rules then flow and discipline breakdown doesn't become a factor, but then the KSI rate per billion vehicle km on US freeways is higher than ours which suggests it isn't a good way to do things.
The reason I disputed the 'DMRB reason' statement is that in AU we do have a significant number of roads with >3 lanes per carriageway, and my observation is firmly that they do proportionally increase capacity as intended. Perhaps it is, as you suggest, owing to our freedom to overtake on either side, as in the USA. By the way, our practise is not "pick a lane and stay in it", but there is indeed more latitude to select a lane by destination, traffic density, distance to intended exit, upcoming-but-still-far-away lane drop, etc.

The UK's (and Norway's and Sweden's) KSI is enviably low. Ours is about double, like most of Western Europe and Canada. The US rate is double again. However, I don't think these differences are related much to carriageway widths or to lane protocols. I think they're related more to societal attitudes (esp. in the USA case), road law and its enforcement, and vehicle standards. (note to self: look more deeply into WHO country-comparison statistics).

Back on the >3 lanes topic (and sorry, I'm already OT for the thread), my belief is that (in the UK) >3 lanes might not provide proportionally increased capacity under normal traffic, but it will under congestion. In that situation, your traffic becomes rather like ours: speed-differential laminar flow disappears. And after all, widening is mainly to address congestion isn't it?

BTW, as we discussed not long ago in other threads, M25 J14-15-16 is terrible simply because it was very poor (simplistic) design. Is the J10-14 widening really a waste though?
As well as the absurd junction spacing there is simply insufficient capacity through J15 for the M25. At 146,054 AADT it is the second busiest three lane link in the country after M60 J1-2, which is not exactly renowned for freeflow conditions and has no D5+ anywhere nearby. Normally D3Ms get ALRed around 100,000 AADT. Even with full C/D lanes and braiding approaching J15 there would still be severe congestion if the mainline remained three lanes through J15.

I think I'd be right in saying that 5+ lane carriageways are only used in the UK where there is a lane drop/gain at both ends - and often a multiple lane drop/gain. I suspect that a lot of the supposed problems with D5M are because they are used at locations where lane discipline inevitably breaks down due to lane drops and, typically, junction spacing that is inadequate to the huge turning volumes. It's a vicious circle - DMRB says use D5M only as a last resort, so it's only used in inevitably congested locations, which are then taken to confirm the failings of the standard.

In other countries where D5M is a normal standard, including for long stretches, there are no such problems. J6A to 10 would be a perfect location for "five lanes without tight junction spacing and lane drops up the wazoo" but I suspect the insularity of UK highway design precludes it.
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Re: M1 J6A-10 D5 ALR

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jackal wrote: Tue Oct 12, 2021 12:28 In other countries where D5M is a normal standard, including for long stretches, there are no such problems. J6A to 10 would be a perfect location for "five lanes without tight junction spacing and lane drops up the wazoo" but I suspect the insularity of UK highway design precludes it.
Do you have an example of a long stretch of D5M in another country that doesn't have issues (and doesn't have offside shoulders/verges)?

As well as the lane discipline / congestion issue with 3+ lanes which is the main reason why DMRB doesn't allow it, the other issue is breakdown safety. A vehicle suffering from a blowout or a major engine failure in L4 of a D4ALR (or D4M) can be difficult to get to an ERA or HS. It would be even worse with a D5ALR, having to cross 4 lanes of traffic with limited / no power and then continue onto an ERA. Even if you suffer a blowout 200m away from an ERA, it is unlikely you can safely cross 4 lanes of traffic to get to the nearside within 200m, so have to continue to the next ERA, yes the same issue applies to D5M although it doesn't matter at what point you reach the nearside. ERAs would have to be so common you might as rather have an discontinuous hard shoulder.
In addition, with more than 4 lanes you really ought to consider an offside shoulder or ERAs, which of course DMRB doesn't allow either. Plus offside ERAs may be confusing/dangerous as if you are in lane 3 of a D5ALR you may consider the offside since you don't have to pass through the line of lorries in L1 & L2, and end up cutting in front of 70mph+ L5 traffic rolling along at 30mph to reach an ERA.

D5ALR just doesn't seem sensible in the current day. Once issues with lane discipline and handling of breakdowns can be consistently be safely carried out from L5 then maybe D5ALR may be sensible, but I don't see that happening until automated driving becomes the norm, and that isn't for many decades to come.
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Re: M1 J6A-10 D5 ALR

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jervi wrote: Tue Oct 12, 2021 17:25
jackal wrote: Tue Oct 12, 2021 12:28 In other countries where D5M is a normal standard, including for long stretches, there are no such problems. J6A to 10 would be a perfect location for "five lanes without tight junction spacing and lane drops up the wazoo" but I suspect the insularity of UK highway design precludes it.
Do you have an example of a long stretch of D5M in another country that doesn't have issues (and doesn't have offside shoulders/verges)?
Thought you could sneak in the offside shoulders without me noticing, eh? :wink: Still, there are many decent stretches of D5M around US cities, and I expect a reasonable number without offside shoulders.
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Re: M1 J6A-10 D5 ALR

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jackal wrote: Tue Oct 12, 2021 18:08
jervi wrote: Tue Oct 12, 2021 17:25
jackal wrote: Tue Oct 12, 2021 12:28 In other countries where D5M is a normal standard, including for long stretches, there are no such problems. J6A to 10 would be a perfect location for "five lanes without tight junction spacing and lane drops up the wazoo" but I suspect the insularity of UK highway design precludes it.
Do you have an example of a long stretch of D5M in another country that doesn't have issues (and doesn't have offside shoulders/verges)?
Thought you could sneak in the offside shoulders without me noticing, eh? :wink: Still, there are many decent stretches of D5M around US cities, and I expect a reasonable number without offside shoulders.
Offside shoulders are conditional of federal funding for interstates so it is only very old freeways that were usually later added to the system that get away with not having them. Short lengths of D5 such as I-80's Eastshore Fwy north of Oakland, CA fall into this category. https://goo.gl/maps/s6VrsRnAPQKRcp3h6 this marks a good transition on (D3/D4) I-30 from modern standards to older ones.

You will be very hard pressed to find freeways wider than D4 in the north east of the USA either, due to urbanisation and land costs. Long sections use C/D lanes - see the New Jersey Turnpike or, north of the border, Hwy 401 around Toronto.
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Re: M1 J6A-10 D5 ALR

Post by Peter Freeman »

jackal wrote: Tue Oct 12, 2021 12:28 It's a vicious circle - DMRB says use D5M only as a last resort, so it's only used in inevitably congested locations, which are then taken to confirm the failings of the standard.
I totally agree. It's almost a 'setup' - use major widening to solve a problem where it's clearly the wrong solution, and then blame the continuing problem on your 'solution'.

J14A-15 is the perfect example. From 14A, aiming for M25 north, you need to achieve either 2 or 3 lane changes to the right, across motorway-speed traffic that's aiming for M4, into slow (sometimes crawling) traffic in lane 4, all within 1km. That's a setup.
Last edited by Peter Freeman on Wed Oct 13, 2021 09:31, edited 1 time in total.
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Re: M1 J6A-10 D5 ALR

Post by ManomayLR »

Peter Freeman wrote: Wed Oct 13, 2021 08:11
jackal wrote: Tue Oct 12, 2021 12:28 It's a vicious circle - DMRB says use D5M only as a last resort, so it's only used in inevitably congested locations, which are then taken to confirm the failings of the standard.
I totally agree. It's almost a 'setup' - use major widening to solve a problem where it's clearly the wrong solution, and then blame the continuing problem on your 'solution'.

J14A-15 is the perfect example. From 14A, aiming for M1 north, you need to achieve either 2 or 3 lane changes to the right, across motorway-speed traffic that's aiming for M4, into slow (sometimes crawling) traffic in lane 4, all within 1km. That's a setup.
This is J14A-15 of M25 right?
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Re: M1 J6A-10 D5 ALR

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oops - I meant M25 - edited now :oops: .
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Re: M1 J6A-10 D5 ALR

Post by jackal »

Bryn666 wrote: Tue Oct 12, 2021 19:46
jackal wrote: Tue Oct 12, 2021 18:08
jervi wrote: Tue Oct 12, 2021 17:25

Do you have an example of a long stretch of D5M in another country that doesn't have issues (and doesn't have offside shoulders/verges)?
Thought you could sneak in the offside shoulders without me noticing, eh? :wink: Still, there are many decent stretches of D5M around US cities, and I expect a reasonable number without offside shoulders.
Offside shoulders are conditional of federal funding for interstates so it is only very old freeways that were usually later added to the system that get away with not having them.
Many D5+ Los Angeles freeways have no inner carriageway, interstates and state/US routes alike. I'm not up on the construction dates of relevant sections of the I-5 or I-405, for instance, but suspect the rules allow for some compromise with the reality of limited space and ever growing traffic - indeed I suspect offside shoulders may have been constructed and then reclaimed, often for HOV lanes.
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