New Lower Thames Crossing

[Truvelo]

Perhaps I haven't read clearly enough, but the picture makes it look like a D2M. Surely that's not wide enough?!

Dual 2-lane would be a very costly act of false economy.

However, I'm amazed by the quality of the junctions. This reminds me of looking through unbuilt motorway plans of the 1960s/early 70s such as the Ringways. I wonder if these tunnel plans will suffer the same fate as the Ringways or whether we will actually see a four level stack on the A13?

[sotonsteve]

It does look like the plans are just for a D2, as opposed to a D3 or D3M. A D2 would fill up in the opening year easily.

[MorganFlint M40 A40]

I have gone for option C with the hopes of a tunnel with a blue line running through the route and free flow slips for the A229 in the direction of Dover and the new crossing.

[Johnathan404]

And here is Route 4's

A13~LTC4.png

Wow!

Nice to know somebody has a nice job!

[frediculous_biggs]

Perhaps I haven't read clearly enough, but the picture makes it look like a D2M. Surely that's not wide enough?!

Dual 2-lane would be a very costly act of false economy.

However, I'm amazed by the quality of the junctions. This reminds me of looking through unbuilt motorway plans of the 1960s/early 70s such as the Ringways. I wonder if these tunnel plans will suffer the same fate as the Ringways or whether we will actually see a four level stack on the A13?

Having looked at the detailed diagrams, it certainly appears to be D2. It does mention "motorway-to-motorway" so I assume the new link will be a motorway (M10 anyone? ). I suppose the problem is that if the link is D4M, say, there will be awful merging where it joins the M25 plus I shudder to imagine the works required to widen the A229.

The new junctions do look very impressive which is good to see. I need to look again, but it suggested free flow slips from the M2 E to A229 S and from A229 S to M20 E. I didn't see a detailed design of those, though. They would need to be introduced as the two junctions would be a nightmare otherwise. It will be interesting to see how they fit in considering there is a village and HS1 portal in close proximity to M2 J3.

As an aside, it is interesting to note that the M2 at J3 will need Dover removing as a forward destination (in a similar way to the A2 does at M25 J2).

[Haydn1971]

Not sure it's been said upthread... Cheap solution would be to take off the tolls and streamline the junctions North and South of the river, would delay the need for a new crossing.

[Patrick Harper]

I'd rather see a second bridge next to QEII, freeing up the tunnels for local access and potentially closing the gap between the two ends of the M25. Much cheaper than a new stretch of motorway/expressway.

[si404]

Perhaps I haven't read clearly enough, but the picture makes it look like a D2M. Surely that's not wide enough?!

Dual 2-lane would be a very costly act of false economy.

Indeed! Thankfully it's a consultation, so we can tell them that!

It does seem that they expect it to be about the M2 corridor only in Kent (the link to the M20 has been dropped, though it does appear in the options report) and talk of Dover/Channel Tunnel is absent). Ie that this is a local link that is useful for the Medway Towns and Gravesend (and perhaps Canterbury/Thanet/Sheerness, though they are ignored) to South Essex and The NORTH, rather than the main route between France and the NORTH.

The Dartford option was for another 4 lane bridge giving 6 lanes in each direction (tunnel returning to two-way, though strangely not for local traffic, but through traffic forming the 'fast' lanes of the 6 lane arrangement between the A2 and A13) - and I believe remains as Option 1, and I think they copied that capacity over to option C, not realising how much traffic it would get because it cuts the corner off (and not just for cross-river movements, but also for M25 to South Essex) even without the link to the M20.

And, of course, the junctions seem over-powered given the narrow nature of the mainlines (though it's nice to have free-flowing designs). I'm pretty sure that there is no 4-level stack in the world where one of the routes is narrower than D3, but Option 4 is looking at both being merely D2.

Not sure it's been said upthread... Cheap solution would be to take off the tolls and streamline the junctions North and South of the river, would delay the need for a new crossing.

There's already no tollbooths (given they were everywhere else, surely there were VMSs up in Yorkshire with the cryptic message of "DART CHARGE 30TH NOV" 14-17 months ago?). Streamlining junctions - how do you mean? The M25/A13 junction could do with some work, but they don't cause the queues and improvements will simply dump more traffic onto the crossing faster. Local traffic using J1A, J1B and J31 would simply divert to the A2 and A13 and clog up J2 and J30 if you close junctions.

[Iain]

I'm a bit disappointed to see the proposed junction with the M2 doesnt allow for any connections between the A289 and LTC. This means people from the Medway Towns will be expected to take the M2 rather than the Medway Tunnel.

[Haydn1971]

There's already no tollbooths (given they were everywhere else, surely there were VMSs up in Yorkshire with the cryptic message of "DART CHARGE 30TH NOV" 14-17 months ago?).

I was aware of the toll booth removal, I've not driven through there since the changes but as I understand it there's still a unnecessary collection of obstructions with the dart lanes that if removed, would ease the pain.

Streamlining junctions - how do you mean? The M25/A13 junction could do with some work, but they don't cause the queues and improvements will simply dump more traffic onto the crossing faster. Local traffic using J1A, J1B and J31 would simply divert to the A2 and A13 and clog up J2 and J30 if you close junctions.

The close proximity of the junctions both sides will have an impact on the absolute flow possible across/under the Thames, it's a small factor, but as was found with ramp metering, a small change can make a large difference.

[M19]

I would have extended the route to the M11 J8 and from thereon widen the M11, voila nice strategic link from the ports nicely bypassing the M25 completely.

[Fluid Dynamics]

Could the logic behind D2M be that the M26 copes delivering a similar function for the southern arm of the M25 as D2M? D2M into D4M works better than D3M at either end. The big question is that whilst you would expect all existing A2 bound traffic travelling southbound on the M25 to take the new tunnel, the traffic heading for the M20 might be more mixed unless the A229 junctions can handle the demand.

The tunnels from the images appear D2M so could allow for future hard shoulder running. I imagine the tunnel experience would be a bit like the Westerscheldetunnel for those who have driven it.

Overall I think the proposals are on balance positive and I think are much better than trying to ram more capacity through Dartford, it also adds some contingency should Dartford be closed due to high winds or other factors.

[darkcape]

Certain routes may be good for D2M but I don't think this is it. There will be a lot of HGV freight heading to the ports, with only two lanes it'll be rolling roadblocks for the 14 miles, just like parts of the A14 & A42. Also looking at the A229 junctions I feel they still will need upgrading, some form of freeflow slips from NB A229 to NB M2 etc, I've never driven it but the existing setup seems convoluted and confusing (though better than at-grade roundabouts). Upgrades at the S2 end of the A2 into Dover may also be a good idea.

Shame all that money adding the viaducts to the M25/A2 junction is now wasted too.

[c2R]

There's already no tollbooths (given they were everywhere else, surely there were VMSs up in Yorkshire with the cryptic message of "DART CHARGE 30TH NOV" 14-17 months ago?).

I was aware of the toll booth removal, I've not driven through there since the changes but as I understand it there's still a unnecessary collection of obstructions with the dart lanes that if removed, would ease the pain.

Southbound, no. Northbound, there are signals to control access to the tunnels, i.e. if vehicles carring dangerous goods need to be escorted through, the traffic can be halted and escorted. Also northbound, the eastern tunnel is higher, so congestion is caused by high HGVs needing to move to lane 3. Not ideal, but not easy to remedy either.

[Bryn666]

Given this new route will invariably be tolled that means Dartford will keep tolls too.

How much traffic using the M25 and Dartford is actually strategic, and how much is starting in Essex and ending in Kent (and vice versa). I'd argue that if the LTC is built as D2M that it is going to reduce the burden on Dartford but not eliminate the demand.

If there were no junctions on the LTC corridor other than the terminal ends then it would be a strategic link only, as it stands the danger is it will simply facilitate huge growth on the Medway shores and be overwhelmed with local traffic.

It's going to be a fine balancing act here.

[WHBM]

I'm pretty sure that there is no 4-level stack in the world where one of the routes is narrower than D3,

From Almondsbury the (built 1996) M4 towards Wales is just D2M. Always comes as a bit of a surprise.

[Chris5156]

If there were no junctions on the LTC corridor other than the terminal ends then it would be a strategic link only, as it stands the danger is it will simply facilitate huge growth on the Medway shores and be overwhelmed with local traffic.

It's going to be a fine balancing act here.

But if it really was a strategic link - and not for local traffic - it would have to reach the M20, which it doesn't.

If it really was a strategic link - let's say from the M20 direct to the M25 without intermediate junctions, catering solely for traffic from SE Kent and the Channel Ports heading to points north of London - D2M would be entirely adequate. But it has more scope for local traffic to use it than that, and local traffic is the bulk of the traffic crossing the Thames.

So the first question really has to be: what is the new crossing for? Only once you know that can you figure out whether the cross-section and interchanges are suitable.

[roadtester]

Two thoughts/questions.

AIUI one purpose of the new crossing is to help provide resilience but if all or part of the Dartford Crossing was out of action, how realistic would the this route really be as an alternative in terms of its location, capacity and ways in which it integrates with the existing network?

Would something like this, which has the potential to soak up a lot of the local and channel port crossing traffic, have been a better idea than the Dartford Bridge back in the day (one problem I can see is the AIUI unsuitability of the older tunnel for larger vehicles)? In other words, if we'd gone for this in place of the bridge in the first place, could we have avoided the expense of building the bridge altogether?

[Phil]

I think (unless Boris Island went ahead) better x-thames links within the M25 would be better (third blackwall bore, A205/A406 link and one between that and the M25)

If big money is going to be spent then replacing both the current Blackwall bores with two straighter 3 lane bores would work wonders. A third Blackwall bore, presumably 2 lane, will offer some benefit but unless one bore is two way then there would have to be some form of tidal flow and there's still the problem of the original bore having too many tight bends.

Please remember that, as far as Central Government / DfT / Highways England are concerned all roads within the GLA area (other than the tail ends of the M1, M4 & M11) are the sole concern of the the London Mayor & Assembly (through TfL). As such any talk of doing anything at Blackwall (or GSJing the remaining at grade junctions on the A40 / A406) is pointless as far as Highways England / the DfT are concerned - roads within London are a devolved matter and absolutely nothing to do with them and as such have no relevance to the Lower Thames crossing which is being designed to help relieve the problems on Highways England / DfT administered roads only.

Basically if you want improvements at Blackwall you need to be campaigning to the London Mayor and the GLA for them to happen - but as has been explained before, without a large wad of cash from Central Government, radical improvements cannot be afforded by the GLA without tolling to pay for it. Even then, with the GLA elected by city dwellers, spending big money on roads is politically a non starter in a city that struggles worth air pollution issues and where there are plenty of public transport improvements like a comprehensive upgrade to Bank Underground station to keep the city moving.

[Phil]

Would something like this, which has the potential to soak up a lot of the local and channel port crossing traffic, have been a better idea than the Dartford Bridge back in the day (one problem I can see is the AIUI unsuitability of the older tunnel for larger vehicles)? In other words, if we'd gone for this in place of the bridge in the first place, could we have avoided the expense of building the bridge altogether?

Not really - the M25 being a 3 lane motorway (as built) plus the pre existing A2-A13 traffic meant that the two D2 bores would simply not have coped on their own - hence the bridge (the need fopr which was identified well before the M25 was complete, even though it did not open till after the M25 itself was finished.

If anything the argument is that rather than only building a bridge for southbound traffic and incorporating the A282 into the Orbital route, a proper D3M bridge should have been built for M25 traffic with no junctions between the A2 & A13 (thus allowing a more gentle gradient and possibly a better location of the toll booths). This would have prevented the current the need for lorries to use the right hand bore or for traffic signals to manage dangerous goods plus it would have separated local traffic (from the A225 & A296) and orbiting M25 traffic.

But to return to the prescient, the advantage of the Lower Thames crossing being out at Gravesend is it separates SE - NW / N / NE flows from S / SW - NE flows (which will continue to use Dartford having arrived via the M25). It also adds resilience to the network (having yet another bridge at Dartford and even wider approach roads is still having all your eggs in one basket so to speak) plus it aids cross river connectivity in the Gravesend / Medway area.