New Lower Thames Crossing

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jackal
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Re: New Lower Thames Crossing

Post by jackal »

Peter Freeman wrote: Sun Mar 20, 2022 12:19
jackal wrote: Sun Jan 16, 2022 17:00 There's also a separate scheme for Tilbury access, which I imagine will be a GSJ near the northern tunnel portal and link road, and which would seem to render the A1089 to LTC slip superfluous.
That junction just north of the river, serving Tilbury and a service area, is shown on one of the fly-throughs (perhaps I'm watching an out-of-date video?). Is that junction still planned? Guess what the GSJ type is - yes, a two-bridge roundabout!

I still think, having reminded myself of what's going on by a quick flick through this thread, that the LTC is being under-engineered in several ways -

1. I understand that there will be modifications to the J29 stackabout. I know that one mod is a 4th through-lane on the M25 :yes:. I presume left turn bypasses :thumbsup:. I suspect signalisation :thumbsdown:. I wonder whether any consideration was given to replacing it :shhh: ...?

2. I don't like any of the reductions to carriageway widths through junctions. I do understand 3+1=4, and other such simplistic lane sums. And I do understand that a lane drop can facilitate a subsequent lane gain. But skimping on width where merging or diverging is taking place is asking for trouble. Keep the width, get the diverging or merging done, then drop the surplus lane(s).

3. The braid at the fork northbound probably is required, but only (as already raised above) because of the loss of merging distance caused by that extravagent swooping curve. Otherwise, a reversal of the southbound (weaving) fork would suffice. The J29 noses are not actually that close to the LTC's. You just need to thin the lane occupancy down by having (more than) adequate width (and perhaps a 60mph limit, and J29 ramp metering :stir:).

4. I'm concerned by some very long single lane connectors. I actally like single lane ramps and connectors, when they match low volumes of traffic, but they shouldn't be too long. The problem that occurs is that platoons form, owing to slower vehicles developing tails. These platoons cause havoc as they all try to merge at once. The solution is for the connector to start as one lane, expand to two lanes in order to allow overtaking of the slow-coach, then compress to single lane once again for the merge.

5. Finally, the project is probably not quite ambitious enough. It will be overwhelmed in 20 years.

Apart from that lot, it's still a great project. Let's go, and cease all this shilly-shallying!
There is no Tilbury link in the current version: https://highwaysengland.citizenspace.co ... ements.pdf

1. Yes, two left turn freeflow filters and full signalisation (it's already half signalised). It's a solid upgrade and it was never realistic to expect more given the state of the A127. If the LTC had to solve all nearby road problems it would never get built.
2. I feel the design is noticeable actually for how little carriageway width drops through major junctions. A large majority of the time a hard shoulder is provided for, I suppose, maintenance and future proofing. At the A2 junction there is even a hard shoulder and an extra lane of hatching provided eastbound.
3. If you look at earlier designs for the M25 junction, the LTC northbound crosses the railway and back again, which would have allowed it to merge into the M25 a bit earlier and removed the need for braiding. But the cost and hassle of two additional railway bridges is really not worth it, hence the current design, which has the LTC northbound running parallel to the railway rather than crossing it, and merging in a bit later. Even so, I agree, the braiding is not absolutely required as the spacing isn't very tight, but they are to be applauded for providing it as it will greatly smooth the flow of traffic at the very high volumes and HGV % on this section of the M25, and it only requires one bridge (admittedly skewed).
4. I'm not really seeing any very long single lane connectors? The longest I can see is LTC to A127, which is quite long but not really enough to justify two lanes with a conflict point where the second lane drops.
5. It's very ambitious IMO. The main sticking point is "only" having three lanes through the tunnel, but that's understandable for the technical reasons rehearsed in my previous post. And in any event the more pressing pinch points will be off the route itself, for instance on the M25 north of J29, on the A13 east, and the A229 at Blue Bell Hill. If the LTC were somehow built on a significantly larger scale with a four lane tunnel it would simply have capacity that could never be utilised due to all the other constraints - and those constraints would be less likely to be eased as the LTC would have sucked up all the funding. For instance, you can see from the design of the LTC/A13 junction that traffic is funnelled onto the A13 more than the LTC (i.e., two turns to/from the A13, only one to/from the LTC), and the A13 is only three lanes after the current upgrade, and even drops to two a couple of junctions along. A D4 tunnel would be fabulously expensive and something of a white elephant given the surrounding network.

My complaints are smaller, mostly to do with the weird Tilbury access. They should either not have any direct access, with that to come with the future scheme, or provide it in both directions. I can't see any scenario where access in one direction makes sense - it's not enough if the future scheme doesn't happen, and redundant if it does.
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jackal
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Re: New Lower Thames Crossing

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PS: If you think the current scheme is unambitious, check out the Route B options from 2012:

Option B bridge - Copy.JPG

Option B tunnel - Copy.JPG
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Re: New Lower Thames Crossing

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jackal wrote: Sun Mar 20, 2022 19:14 PS: If you think the current scheme is unambitious, check out the Route B options from 2012:
I haven't really studied the other options, but I did take a glance at the one you recently mentioned in another thread, where the LTC briefly shares the A127 alignment. Not bad, north of the river anyway. It even has a stack with the A13. But the 'briefly' might be too brief - I didn't really note the weaving length.

BTW, it's hard to believe that this project has been in serious design and consultation for ten years (or more?) with still no action on the ground.
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Re: New Lower Thames Crossing

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Peter Freeman wrote: Sun Mar 20, 2022 23:48 BTW, it's hard to believe that this project has been in serious design and consultation for ten years (or more?) with still no action on the ground.
It wouldn't surprise me if it never sees the light of day. I am still only 50% convinced it will ever be built given the huge cost.

Regarding those Route B options Jackal posted is the section on those maps the only stretch of new road to be built? If so it would surely be a lot cheaper than what's currently planned. The connection to the M25 north of the tunnel would obviously be an issue if nothing is done at Thurrock but a scheme with only four miles of new road vs 14 miles will appeal to the bean counters.
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jackal
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Re: New Lower Thames Crossing

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Truvelo wrote: Mon Mar 21, 2022 00:07 Regarding those Route B options Jackal posted is the section on those maps the only stretch of new road to be built? If so it would surely be a lot cheaper than what's currently planned. The connection to the M25 north of the tunnel would obviously be an issue if nothing is done at Thurrock but a scheme with only four miles of new road vs 14 miles will appeal to the bean counters.
Yes, that's all they were planning to build for B. It would have cost about half of C, which was the early version of what is now proposed.

"Most likely" costs are below. A would provide an extra crossing and link road capacity at Dartford, and Cvariant is an add-on for C that widens the A229 to three lanes and provides freeflow structures at the M2 and M20.

Option A
Four lane structure: bridge £0.91bn, immersed tunnel £1.18bn, bored tunnel £1.15bn
Four lane structure+link roads: bridge £1.25bn, immersed tunnel £1.6bn, bored tunnel £1.57bn
Six lane structure: bridge £1.2bn, immersed tunnel £1.51bn, bored tunnel £1.81bn
(No estimate provided for six lane link roads.)

Option B
Four lane structure: bridge £1.68bn, immersed tunnel £1.83bn, bored tunnel £1.72bn
Four lane structure+link roads: £1.78bn, immersed tunnel £2.02bn, bored tunnel £2.17bn
Six lane structure: bridge £2.11bn, immersed tunnel £2.34bn, bored tunnel £2.71bn
(No estimate provided for six lane link roads.)

Option C
Four lane structure: bridge £1.82bn, immersed tunnel £1.83bn, bored tunnel £1.93bn
Four lane structure+link roads: bridge £3.24bn, immersed tunnel £3.09bn, bored tunnel £3.15bn
Six lane structure: bridge £2.29bn, immersed tunnel £2.35bn, bored tunnel £3.04bn
(No estimate provided for six lane link roads.)

Cvariant
£1.77bn

And here are the major junctions for Option C as it was planned at the time. The M2 and M25 junctions are passable, though less ambitious than the current proposals, but the A13 junction was just ridiculous! Not to mention that the whole thing would be only two lane.

M2 2012 - Copy.JPG

A13 2012 - Copy.JPG

M25 2012 - Copy.JPG

The report (figures are in the appendix): https://www.gov.uk/government/publicati ... ing-report
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Re: New Lower Thames Crossing

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Peter Freeman wrote: Sun Mar 20, 2022 23:48 BTW, it's hard to believe that this project has been in serious design and consultation for ten years (or more?) with still no action on the ground.
Is it? I would have thought that was entirely normal for a British road project. This topic is only 9 years old, and started when the routes were completely undecided. The preferred route wasn't announced until 2017, so really there is only 5 years of detailed design and consultation, including covid delays
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Re: New Lower Thames Crossing

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jackal wrote: Sun Mar 20, 2022 18:36 2. I feel the design is noticeable actually for how little carriageway width drops through major junctions. A large majority of the time a hard shoulder is provided for, I suppose, maintenance and future proofing. At the A2 junction there is even a hard shoulder and an extra lane of hatching provided eastbound.
All the way southwards from M25 J29A to LTC J1* is, I suppose, technically, 'between' junctions. Nevertheless, I'm sure that whole length, with only 2 mainline lanes southbound (and not future-proofed with a H.S.), is going to struggle, despite 4+2>5.

(* LTC J1, for shorthand, is where LTC meets A13 and A1089)
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Re: New Lower Thames Crossing

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jackal wrote: Sun Mar 20, 2022 18:36
Peter Freeman wrote: Sun Mar 20, 2022 12:19 4. I'm concerned by some very long single lane connectors. I actally like single lane ramps and connectors, when they match low volumes of traffic, but they shouldn't be too long. The problem that occurs is that platoons form, owing to slower vehicles developing tails. These platoons cause havoc as they all try to merge at once. The solution is for the connector to start as one lane, expand to two lanes in order to allow overtaking of the slow-coach, then compress to single lane once again for the merge.
4. I'm not really seeing any very long single lane connectors? The longest I can see is LTC to A127, which is quite long but not really enough to justify two lanes with a conflict point where the second lane drops.
Agreed, on re-checking. I was thinking of that one from LTC to J29, and one leading from A1089 looping 180 degrees to join LTC southbound; but agreed, they're not too long.

It is worth noting though, that a 2-lane connector road, usually without a shoulder, is hardly wider than a 1-lane connector, which invariably does have a shoulder (for breakdown or sight distance or both).

The layout I described has been used very effectively at several points on Melbourne's network, for 'de-platooning'. The more usual way here now, of course, is by metering signals. In fact, there are places where the former layout has been re-purposed for metering, with little pavement re-work required.
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Re: New Lower Thames Crossing

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Herned wrote: Mon Mar 21, 2022 10:46
Peter Freeman wrote: Sun Mar 20, 2022 23:48BTW, it's hard to believe that this project has been in serious design and consultation for ten years (or more?) with still no action on the ground.
Is it? I would have thought that was entirely normal for a British road project. This topic is only 9 years old, and started when the routes were completely undecided. The preferred route wasn't announced until 2017, so really there is only 5 years of detailed design and consultation, including covid delays
I agree. Within the context of British infrastructure planning, this project is moving at breakneck speed. The only thing hard to believe for me is how quickly it's moving towards construction, given that it's major new roadbuilding in the south east of England and a decade ago the project didn't even exist. It's almost unheard of.
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Re: New Lower Thames Crossing

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Chris5156 wrote: Tue Mar 22, 2022 09:05 The only thing hard to believe for me is how quickly it's moving towards construction, given that it's major new roadbuilding in the south east of England
Essex is very roadbuilding friendly, mind. And even Kent to an extent. Surrey, Berks or Bucks would be a different story.
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Re: New Lower Thames Crossing

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jackal wrote: Tue Mar 22, 2022 09:09
Chris5156 wrote: Tue Mar 22, 2022 09:05 The only thing hard to believe for me is how quickly it's moving towards construction, given that it's major new roadbuilding in the south east of England
Essex is very roadbuilding friendly, mind. And even Kent to an extent. Surrey, Berks or Bucks would be a different story.
This is very true - east of London is not the same as west of London.
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Re: New Lower Thames Crossing

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I still think in a country that had a sensible transport strategy we'd have also been planning for a HS1-HS2 connection avoiding London entirely following the general LTC/M25 line towards Aylesbury, but that was kyboshed with Brexit and the fact we're stuck in reverse gear transport wise.

Imagine being able to load your truck onto a train away from London and avoid sitting in traffic entirely... pfft, too sensible.
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Re: New Lower Thames Crossing

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^ Extend Le Shuttle to Hendon?
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Re: New Lower Thames Crossing

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jackal wrote: Sun Mar 20, 2022 18:36 It's very ambitious IMO.
This is 20km of D2/3 AP, 4km of D3 tunnel, and 3km of an existing route enhanced to a braided interchange. And it's the only project of this scale currently on NH's agenda. Our benchmarks for ambition obviously differ.
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Re: New Lower Thames Crossing

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Bryn666 wrote: Tue Mar 22, 2022 09:38 I still think in a country that had a sensible transport strategy we'd have also been planning for a HS1-HS2 connection avoiding London entirely following the general LTC/M25 line towards Aylesbury, but that was kyboshed with Brexit and the fact we're stuck in reverse gear transport wise.

Imagine being able to load your truck onto a train away from London and avoid sitting in traffic entirely... pfft, too sensible.
That is why we have intermodal terminals. If you want to send a container from Tilbury to Glasgow on a train its rather easy, no truck required.

Plans for an HS1-HS2 link were dropped well before Brexit on economic grounds. It was just not economically justifiable.
https://railuk.com/rail-projects/hs2/go ... rail-link/

There is nothing to stop freight trains running from China to the UK, in fact such trains do run.
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Re: New Lower Thames Crossing

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KeithW wrote: Wed Mar 23, 2022 09:33
Bryn666 wrote: Tue Mar 22, 2022 09:38 I still think in a country that had a sensible transport strategy we'd have also been planning for a HS1-HS2 connection avoiding London entirely following the general LTC/M25 line towards Aylesbury, but that was kyboshed with Brexit and the fact we're stuck in reverse gear transport wise.

Imagine being able to load your truck onto a train away from London and avoid sitting in traffic entirely... pfft, too sensible.
That is why we have intermodal terminals. If you want to send a container from Tilbury to Glasgow on a train its rather easy, no truck required.

Plans for an HS1-HS2 link were dropped well before Brexit on economic grounds. It was just not economically justifiable.
https://railuk.com/rail-projects/hs2/go ... rail-link/

There is nothing to stop freight trains running from China to the UK, in fact such trains do run.
Freight trains won't be using HS2 anyway. Indeed a major reason for building HS2 is to make space on the WCML for more freight traffic
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Re: New Lower Thames Crossing

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Scratchwood wrote: Wed Mar 23, 2022 10:39 Freight trains won't be using HS2 anyway. Indeed a major reason for building HS2 is to make space on the WCML for more freight traffic
Indeed.
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Re: New Lower Thames Crossing

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KeithW wrote: Wed Mar 23, 2022 09:33
Bryn666 wrote: Tue Mar 22, 2022 09:38 I still think in a country that had a sensible transport strategy we'd have also been planning for a HS1-HS2 connection avoiding London entirely following the general LTC/M25 line towards Aylesbury, but that was kyboshed with Brexit and the fact we're stuck in reverse gear transport wise.

Imagine being able to load your truck onto a train away from London and avoid sitting in traffic entirely... pfft, too sensible.
That is why we have intermodal terminals. If you want to send a container from Tilbury to Glasgow on a train its rather easy, no truck required.

Plans for an HS1-HS2 link were dropped well before Brexit on economic grounds. It was just not economically justifiable.
https://railuk.com/rail-projects/hs2/go ... rail-link/

There is nothing to stop freight trains running from China to the UK, in fact such trains do run.
Indeed, intermodal is the only way of doing this - the loading gauge of the network at either end of the Channel Tunnel is insufficient to take lorries and no HS2 proposals would have changed that. Any link between HS1 and HS2 would only have been of use to foot passengers.
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Re: New Lower Thames Crossing

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Shortlist for the £2.3bn tunnelling package:

Bam Nuttall, Ferrovial and Vinci JV
Bouygues Murphy JV; comprising Bouygues Travaux Publics and J Murphy & Sons
Dragados-Hochtief JV; comprising Dragados and Hochtief Infrastructure

Shortlist for the £1.3bn Roads North of the Thames contract:

Balfour Beatty
Kier Eiffage JV

Shortlist for the £600M Kent Roads package:

Bam Nuttall, Ferrovial and Vinci JV
Costain
Kier and Eiffage JV
Skanska

https://www.newcivilengineer.com/latest ... 6-04-2022/
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Re: New Lower Thames Crossing

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"Six changes to Lower Thames Crossing plans go out to consultation"

[*]More public open space to the east of the tunnel entrance in Kent, connected to Chalk Park - the proposed new public park overlooking the Thames
[*]Additional environmental compensation and mitigation with potential woodland and public access
[*]Replace a slip road on the A13 junction with a new link from the Orsett Cock roundabout to the A1089 to reduce traffic impacts on local roads
[*]Modified the access to the northern tunnel portal providing safer operation of the tunnel facilities and better access for emergency services
[*]A new footbridge over the A127 and further improvements for walkers, cyclists and horse riders including improved bridleways
[*]Further refinement of utility works to enable the project to be built

While there's not a huge amount there from a roads perspective, it'll be interesting to see what the A13/A1089/Orsett Cock changes are. As I've mentioned many times, the previous design was good but unbalanced:

A13 LTC 2020 - Copy.jpg

It sounds like they might be adding one of the 'missing' movements, from Orsett Cock to A1089, but I'm not sure what slip road could be 'replaced' with such a movement. Ideally it would be A1089 to LTC, which doesn't seem necessary given a separate connection to Tilbury is planned (the reverse movement is already omitted).

Consultation opens on Thursday.

https://www.newcivilengineer.com/latest ... 6-03-2022/
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