Bridge to Ireland possible rail link and tunnel

[Meerkat]

As soon as you have a fixed link to GB you are going to reguage NI straight away aren’t you?
And then probably down to Dublin too.

 

[Baxenden Bank]

I think there's some consensus around the following three ideas, plus my take on the fourth point:

- A road / rail link either by bridge or tunnel between Great Britain and Northern Ireland is technically feasible on current facts. Little disagreement from anyone here.

- An economic assessment of the benefits of linking Belfast and Dublin with Edinburgh and Glasgow is a good idea. In particular, even if the BCR for a link across the Irish Sea is poor, this will show up the value of the better links between the city pairs on continuous land. It would also be successful as part of wider ideas about economic regeneration for Northern Ireland and for integration economically both between Northern Ireland and Scotland and Ireland and Scotland.

- Such an investigation would need probably a couple of years to report, and it would need the UK Government, Government of Ireland, Scottish Government and Northern Ireland Assembly all onboard so that all respect its conclusions. None would likely be willing to pay more than a token amount of the millions of pounds needed to fund it, so the UK government would have to come up with most of the money.

- The Prime Minister isn't actually looking at any of the above questions, or indeed any wider questions about how the Welsh or Northern English economies might work better with the Irish one (this point clearly needs big cooperation and funding from the Irish Government). He is simply saying 'Look, a bridge!'. Many will disagree with me on this.

So the project is both serious and scatterbrained, simultaneously.

The bridge will need lots of plants though, so it can be a green wildlife corridor too. And on top of each cantilever tower, a 100m statue of Joanna Lumley.

 

[Glenn1969]

But given that the most feasible link is from Portpatrick which doesn't have a rail link presumably adding one would add to the cost (the figure I saw for a road link was £15bn)

 

[Chester1]

The problem there is that there are three stations serving central Belfast, and to get to the one nearest the centre (Great Victoria Street) from the Larne line it would have to go through the other two. So it's dual gauging (which as I mentioned above would cause stepping distance issues) or terminating the through service and the Larne line at somewhere fairly remote from the centre (like Yorkgate which is where it used to terminate before the harbor bridges in the 1970s).

A terminal for services to Scotland and England would need to be big and would a development focus.

This is a political, not an economic project. It's about stitching together the UK more tightly. The "feel" of being able to get a train from Belfast to Glasgow or Manchester or London and vice-versa is what it's aimed at. Counterbalancing the effect of Brexit on the Island of Ireland, which currently seems likely to re-unify itself sometime in the next thirty years.

I agree, its unlikely to be built but the decision to do it would never be based on a BCR, it would be an entirely political decision.

As soon as you have a fixed link to GB you are going to reguage NI straight away aren’t you?
And then probably down to Dublin too.

Dublin wouldn't happen for political reasons. Converting Bangor to Great Victoria Street for a interchange between UK and Dublin services would resolve the terminal location issue described by @edwin_m but would add more cost.

That could mean all services starting and finishing at an expanded Belfast Great Victoria Street.

Irish gauge services:

Belfast - Dublin
Belfast - Derry via Knockmore line - would need track relaying (mothballed but unlike in England, actually kept clear and safe)
Coleraine to Port Rush

UK gauge:

Belfast to Bridge / tunnel to GB
Belfast to Larne
Belfast to Antrim via Bleach Green
Belfast to Bangor

But given that the most feasible link is from Portpatrick which doesn't have a rail link presumably adding one would add to the cost (the figure I saw for a road link was £15bn)

It depends which news outlet you read. A combined rail and road bridge + tunnel has been suggested for £20bn. I am not sure why a bridge would even be considered rather than a tunnel. A tunnel would be vastly more weather resistant and tunneling under the Beaufort Dyke would probably be easier than building a bridge over it. At 400m+ it would be the deepest in the world but surely easier than building a bridge over a toxic explosive, waste dump. The timescales would allow for a petrol + diesel ban from day 1 which would make ventilation easier.

 

[HSTEd]

And so the journey time would be significantly less, no? Since freight wouldn't mind slowing for gauge changers and can bypass Belfast city centre and head south.

I was referring to on the road, rather than on the back of a train.

The problem with freight is that its going to be capable of not much better than 80mph, even if we give it ludicrous amounts of power from a fleet of modern high power electrics.
Which means it's going to take an hour to reach the Bridge from Gretna.
It's highly likely to get in the way of a passenger train, which means a tonne of infrastructure to get around that (probably quite long sections of four track etc).

I certainly wouldn't build anything to exclude freight, but I wonder how much it costs and if it could compete with the inevitable drive through connection.

I know talgo freight wagons did exist, but I don't know if anyone has seriously suggested an operational application for them.

It depends which news outlet you read. A combined rail and road bridge + tunnel has been suggested for £20bn. I am not sure why a bridge would even be considered rather than a tunnel. A tunnel would be vastly more weather resistant and tunneling under the Beaufort Dyke would probably be easier than building a bridge over it. At 400m+ it would be the deepest in the world but surely easier than building a bridge over a toxic explosive, waste dump. The timescales would allow for a petrol + diesel ban from day 1 which would make ventilation easier.

The Portpatrick-Larne alignment doesn't go below 255m or so meters as far as I can tell.
The ultra deep waters are actually further south.

Building a tunnel under Beaufort's Dyke is a rather strange way of saving money.
As far as I know noone has attempted anything like that, or even seriously proposed it.

The safety concerns of having a straight or ner straight descent for 300+ vertical metres in a handful of kilometres and then a similar ascent are substantial.
Nevermind the issues with lighting a fire in what amounts to a 300m tall chimney.

Clearing small areas of the seabed for the installation of bridge piers is going to be considerably cheaper than taking that kind of engineering challenge on.

Even if the base of the structure for a bridge pier sitting on the seabed is 90m in diameter, and you clear out to 130-140m diameter, you are talking about clearing only 1.5ha per ~1100m-1400m bridge span.
If we manage to go to longer spans that figure drops precipitously.

Since we didn't bury any unstable nuclear weapons there, the 90m-250m of water shields any surface activities, and in these depths you are unlikely to use many divers anyway.

As to weather resistance, bridges in Hong Kong don't even fully close for Typhoons. The weather in the North Channel rarely gets that bad.

EDIT:

Assuming 250+m of water for a bridge pier, you would likely dredge the local surface flat, and use the dredging to remove or incidentally detonate anything dangerous in the proposed footprint.

Inspect with UUVs and then drop a Gravity Base Structure pier onto it that has been floating into position from a shore yard.

As soon as you have a fixed link to GB you are going to reguage NI straight away aren’t you?
And then probably down to Dublin too.

The politics of regauging is far too fraught.
Dual gauging or Talgo-bogies is a more likely option.

 

[Chester1]

The Portpatrick-Larne alignment doesn't go below 255m or so meters as far as I can tell.
The ultra deep waters are actually further south.

Building a tunnel under Beaufort's Dyke is a rather strange way of saving money.
As far as I know noone has attempted anything like that, or even seriously proposed it.

Clearing small areas of the seabed for the installation of bridge piers is going to be considerably cheaper than taking that kind of engineering challenge on.

Even if the base of the structure for a bridge pier sitting on the seabed is 90m in diameter, and you clear out to 130-140m diameter, you are talking about clearing only 1.5ha per ~1100m-1400m bridge span.
If we manage to go to longer spans that figure drops precipitously.

Since we didn't bury any unstable nuclear weapons there, the 90m of water shields any surface activities, and in these depths you are unlikely to use many divers anyway.

As to weather resistance, bridges in Hong Kong don't even fully close for Typhoons. The weather in the North Channel rarely gets that bad.

EDIT:

Assuming 250+m of water for a bridge pier, you would likely dredge the local surface flat, and use the dredging to remove or incidentally detonate anything dangerous in the proposed footprint.

Inspect with UUVs and then drop a Gravity Base Structure pier onto it that has been floating into position from a shore yard.



The politics of regauging is far too fraught.
Dual gauging or Talgo-bogies is a more likely option.

If routed through the 255m deep section of the Dyke the tunnel would be slightly shorter than the Seikan tunnel and only 20-25% deeper. The cost estimate might be higher than a bridge but they would be more accurate. There would be two comparable tunnels i.e. Channel Tunnel and Seikan Tunnel.

 

[MarkyT]

The politics of regauging is far too fraught.
Dual gauging or Talgo-bogies is a more likely option.

Gauge converting any major part of Ireland would be very wasteful and largely pointless as the vast majority of trains would not be using the link to England. I think a comparatively short standard gauge compatible route into Belfast would be most likely, and as you suggest any Dublin - Scotland expresses adopting a gauge changing solution by Talgo or CAF. Stadler is also entering the gauge changing market with the new MOB/BLS Golden Pass Express stock for use between Montreux and Interlaken, on metre and standard gauge.

 

[The Ham]

I think there's some consensus around the following three ideas, plus my take on the fourth point:

- A road / rail link either by bridge or tunnel between Great Britain and Northern Ireland is technically feasible on current facts. Little disagreement from anyone here.

- An economic assessment of the benefits of linking Belfast and Dublin with Edinburgh and Glasgow is a good idea. In particular, even if the BCR for a link across the Irish Sea is poor, this will show up the value of the better links between the city pairs on continuous land. It would also be successful as part of wider ideas about economic regeneration for Northern Ireland and for integration economically both between Northern Ireland and Scotland and Ireland and Scotland.

- Such an investigation would need probably a couple of years to report, and it would need the UK Government, Government of Ireland, Scottish Government and Northern Ireland Assembly all onboard so that all respect its conclusions. None would likely be willing to pay more than a token amount of the millions of pounds needed to fund it, so the UK government would have to come up with most of the money.

- The Prime Minister isn't actually looking at any of the above questions, or indeed any wider questions about how the Welsh or Northern English economies might work better with the Irish one (this point clearly needs big cooperation and funding from the Irish Government). He is simply saying 'Look, a bridge!'. Many will disagree with me on this.

So the project is both serious and scatterbrained, simultaneously.

I could see the political advantage of having a bridge scheme being developed when there's another independence referendum, in that the Scottish government wouldn't likely be able to fund it, so the argument would be "vote to stay part of the Union and we'll give you a bridge*" que just enough people thinking that they vote to stay part of the Union this time and once the bridge is built and paid for by the English we'll then push for another referendum.

*Once you have a bridge, the cost of this would need to be repaid if you were to vote to leave the Union.

 

[The Ham]

For freight could you not have a similar thing to there is at the Eurotunnel with it basically being a roll on roll off link, but rather than it being the ferry it's a train.

Whilst this could be by the coast it could also be several miles over land before getting there if there's little advantage in getting additional markets (i.e. of you've got the choice of being on a train though sparsely populated areas or driving then it makes little difference).

The big advantage would be reductions in fuel costs and getting further between lorry driver breaks.

Yes you'd need higher bridges, but if there's not many of them anyway then that's not going to add much to the building costs.

 

[Eddd]

A tunnel would be more resilient and probably have a longer lifespan. A new approach would be needed anyway so it could reach the required depth without too steep a gradient. The evacuation system for rail is tried and tested in the Channel Tunnel.

But a long tunnel doesn't really work for road because of the space needed and safety issues. Some Tories think Thatcher let the side down when she agreed a rail link to France and not a road, so a bridge it is.

 

[The Ham]

A tunnel would be more resilient and probably have a longer lifespan. A new approach would be needed anyway so it could reach the required depth without too steep a gradient. The evacuation system for rail is tried and tested in the Channel Tunnel.

But a long tunnel doesn't really work for road because of the space needed and safety issues. Some Tories think Thatcher let the side down when she agreed a rail link to France and not a road, so a bridge it is.

The simple solution would be to start tunneling further away from the coast.

If you need a station stop, as long as you're not too far down, this could just be underground. Even if you were quite some distance down (say 25m+) you could have the ticket hall underground as well to break up the feel of how far down you've gone.

Just for perspective, ~6m of level difference is what a lot of pedestrian rail over bridges provide. Therefore double this ~12m would be a bit long it it was only stairs (circa 4 flights of stairs), and would start feeling deep on a single escalator. Hence the need to split the journey with a ticket hall.

You could further reduce the feel of the length with a slope down to the top of the escalators so that they start just below ground level.

Likewise by having the escalators stop above platform height with a short walk to descend onto the platforms would also help with the breaking of journey.

However at 25m down, even right at the coast, you're able to reduce the gradient a fair amount, or at least reduced the length of the steepest section of gradient.

As an example of you had a gradient of 1:80 by starting at ground level and then changed it to starting at the last station 25m down this then flattens to 1:89.

 

[Meerkat]

The politics of regauging is far too fraught.
Dual gauging or Talgo-bogies is a more likely option

What is the political problem with reguaging Belfast to Dublin? The Spanish did it.
You can’t practically gauge change freight, and there would surely be a big demand to get the freight trains all the way into Dublin?

 

[HSTEd]

If routed through the 255m deep section of the Dyke the tunnel would be slightly shorter than the Seikan tunnel and only 20-25% deeper. The cost estimate might be higher than a bridge but they would be more accurate. There would be two comparable tunnels i.e. Channel Tunnel and Seikan Tunnel.

Channel Tunnel and Seikan Tunnel aren't really comparable at all, since they aren't road tunnels.

What is the political problem with reguaging Belfast to Dublin? The Spanish did it.

Because dissident republicans and other republican politicians will probably decry it as "railway colonialism", since through services to the rest of Ireland will be damaged in favour of links between GB and NI.

Irish Gauge operations cannot be curtailed in any significant way for political reasons.

You can’t practically gauge change freight, and there would surely be a big demand to get the freight trains all the way into Dublin?

Why?
Even freight trains to vicinity of Larne obtain most of the benefits of freight trains at all, and a drive through crossing will not have such a drive to produce modal shift.

For freight could you not have a similar thing to there is at the Eurotunnel with it basically being a roll on roll off link, but rather than it being the ferry it's a train.
.

But the Channel Tunnel hasn't even managed to drive the Dover-Calais ferries out of the market, let alonet he other crossings to Europe.

If you want to capture as much traffic as possible to the link it has to be a drive through connection.

 

[MarkyT]

What is the political problem with reguaging Belfast to Dublin? The Spanish did it.
You can’t practically gauge change freight, and there would surely be a big demand to get the freight trains all the way into Dublin?

I think some companies are now offering gauge changing axle systems for freight vehicles. Not saying there's been much uptake so far... Spain has one of the lowest rail freight usage figures in Europe, mainly down to the gauge issue which deters what should be the most viable long distance international traffic. What struck me when first crossing the Spanish/French border on the Mediterranean coast was the vast complex of transhipment warehouses and sidings, almost without exception standard gauge served only, and engaged predominantly with transfering rail-borne freight from across Europe to lorries for onward travel into Spain.

 

[Chester1]

Channel Tunnel and Seikan Tunnel aren't really comparable at all, since they aren't road tunnels.


Because dissident republicans and other republican politicians will probably decry it as "railway colonialism", since through services to the rest of Ireland will be damaged in favour of links between GB and NI.

Irish Gauge operations cannot be curtailed in any significant way for political reasons.

A rail only tunnel would achieve much of the political goal at a lower cost. The economics are secondary because they will never justify a fixed link.

Is the Irish loading gauge sufficiently large to fit one of the main European gauges? A conversion would be easier to sell if it included 520mm platforms etc and to allow off the shelf European trains to be ordered. It would look distinctly unbritish and allow "classic compatible" HS2 stock to run to Belfast.

 

[HSTEd]

A rail only tunnel would achieve much of the political goal at a lower cost. The economics are secondary because they will never justify a fixed link.

Once you start down that road you will end up paying 80% of the money for 10% of the gains.

A single track "mousehole" tunnel with no rail improvements on the Scottish side achieves "the political goal" at the lowest overall cost but certainly does not achieve the optimum BCR for the project.
As there are essentially no gains to be had at all.

As the Channel Tunnel has demonstrated, a rail only tunnel is almost useless.
I am almost certian that given recent advances in technology, the bridge solution offers a superior BCR to the tunnel solution.

Is the Irish loading gauge sufficiently large to fit one of the main European gauges? A conversion would be easier to sell if it included 520mm platforms etc and to allow off the shelf European trains to be ordered. It would look distinctly unbritish and allow "classic compatible" HS2 stock to run to Belfast.

As far as I can tell, Irish loading gauge is basically the same as the GB loading gauge, the only difference are that he rails are a few inches further apart.

 

[Meerkat]

Because dissident republicans and other republican politicians will probably decry it as "railway colonialism", since through services to the rest of Ireland will be damaged in favour of links between GB and NI.

Irish Gauge operations cannot be curtailed in any significant way for political reasons.

It’s not “British gauge” it’s standard European gauge, and would have significant environmental and cost benefits. Are there any through services across Dublin toward the border?

Even freight trains to vicinity of Larne obtain most of the benefits of freight trains at all, and a drive through crossing will not have such a drive to produce modal shift.

Especially in this green age the aim would surely be to get full trainloads between GB/Europe and distribution centres on the Dublin outskirts (at least, but regauging toward other centres might be too much)

 

[MarkyT]

As the Channel Tunnel has demonstrated, a rail only tunnel is almost useless.

So 58% market share for cars in 2017 is 'almost useless'????
You will no doubt claim it is not successful because it hasn't totally destroyed ALL ferry competition. I think that's a strength in the overall market and good for customers; they haven't established a complete monopoly!
http://www.travelweekly.co.uk/articles/284236/eurotunnel-sees-increase-in-cross-channel-market-share

 

[HSTEd]

So 58% market share for cars in 2017 is 'almost useless'????
You will no doubt claim it is not successful because it hasn't totally destroyed ALL ferry competition. I think that's a strength in the overall market and good for customers; they haven't established a complete monopoly!
http://www.travelweekly.co.uk/articles/284236/eurotunnel-sees-increase-in-cross-channel-market-share

Yes, yes it is.
The whole point of a fixed crossing is that it has near zero operating costs.
The Chunnel fails at this miserably, and if it's marginal operating cost (given that it is nowhere near full) cannot even drive parallel ferries out of the market then the capital was frankly wasted.

You want to spend many many billions of pounds to take 60% of the ferry traffic and this is somehow going to be better value for money than taking all the parallel traffic and abstracting traffic from other crossings?

Also.... the point of fixed crossings is to produce a monopoly.
This is like saying the Severn Bridge was a disaster because it killed both of the operating ferries and thus reduced "choice".

It is rather telling that noone else has really tried this undersea rail only solution with car carrying trains, anywhere in the world.
Whilst the length of subsea road tunnels continues to escalate.

 

[MarkyT]

Yes, yes it is.
The whole point of a fixed crossing is that it has near zero operating costs.
The Chunnel fails at this miserably, and if it's marginal operating cost (given that it is nowhere near full) cannot even drive parallel ferries out of the market then the capital was frankly wasted.

You want to spend many many billions of pounds to take 60% of the ferry traffic and this is somehow going to be better value for money than taking all the parallel traffic and abstracting traffic from other crossings?

Also.... the point of fixed crossings is to produce a monopoly.
This is like saying the Severn Bridge was a disaster because it killed both of the operating ferries and thus reduced "choice".

It is rather telling that noone else has really tried this undersea rail only solution with car carrying trains, anywhere in the world.
Whilst the length of subsea road tunnels continues to escalate.

There are recent car 'ferry' rail operations in Alpine tunnels. Should these have all been built with parallel roads? Was the channel tunnel not worth it for the rail service possibilities? How much extra capital would have been required for parallel road lanes in the channel and would that have been possible to raise? I think costs could have been at least two or three times that of the rail only version that was built, considering the additional quantity of excavation required for a double lane with hard shoulder in each direction, additional ventilation and emergency measures required. Obviously a bridge is much easier for the narrow problem of dealing with road vehicle emmissions and emergency egress etc, assuming the construction is feasible at all.

 

[33Hz]

The Brenner Base Tunnel currently under constructions is 55km long and costing under €8bn.

An Irish Sea tunnel could be 35km, yet we are told the budget for a bridge would be £20bn.

Why would you not build a tunnel for a fraction of the cost?

 

[HSTEd]

The Brenner Base Tunnel currently under constructions is 55km long and costing under €8bn.

An Irish Sea tunnel could be 35km, yet we are told the budget for a bridge would be £20bn.

Why would you not build a tunnel for a fraction of the cost?

Well you aren't comparing like with like.
Also worth noting that the Brenner Base tunnel manages to come close to beating HS2 for costs.......
So pretty sure there are some major differences there.

Subsea tunnel construction is entirely different from construction a base tunnel in a mountain range.
Base Tunnels have access to the surface where subsea tunnels don't really.
Base tunnels are flat where subsea tunnels obviously aren't.

Etc Etc etc.

Also do you know what the £20bn includes and what the €8bn includes?
Do they include equivalent work packages in both cases.

There are recent car 'ferry' rail operations in Alpine tunnels. Should these have all been built with parallel roads?

Can't really build a bridge across the alps can you?
Or an immersed tube tunnel, which are the two most commonly used technologies for road to cross bodies of water.

Was the channel tunnel not worth it for the rail service possibilities?

Probably not, considering the tunnel tries to do both and costs a fortune more as a result.
A rail only tunnel scheme would have been very different.

How much extra capital would have been required for parallel road lanes in the channel and would that have been possible to raise?

Well other consortia proposed exactly that?
Eurobridge etc that wanted an entirely surface suspension bridge crossing.
Or the combined bridge-tunnel solution of Euroroute.

I think costs could have been at least two or three times that of the rail only version that was built, considering the additional quantity of excavation required for a double lane with hard shoulder in each direction, additional ventilation and emergency measures required. Obviously a bridge is much easier for the narrow problem of dealing with road vehicle emmissions and emergency egress etc, assuming the construction is feasible at all.

As you say, a bridge has major advantages regarding vehicle emissions and emergency egress.

A fire in a tunnel turns into a nightmare that can kill huge numbers of people, a fire on a bridge is relatively easy to fight and much easier to evacuate people from.

 

[33Hz]

Well you aren't comparing like with like.
Also worth noting that the Brenner Base tunnel manages to come close to beating HS2 for costs.......
So pretty sure there are some major differences there.

Subsea tunnel construction is entirely different from construction a base tunnel in a mountain range.
Base Tunnels have access to the surface where subsea tunnels don't really.
Base tunnels are flat where subsea tunnels obviously aren't.

Etc Etc etc.

Also do you know what the £20bn includes and what the €8bn includes?
Do they include equivalent work packages in both cases.

Does anybody know what the £20bn includes? Least of all BoJo? Work packages for the Brenner Base Tunnel can be seen at https://www.bbt-se.com

The Brenner Base Tunnel is far from flat. There is a 185m height difference between north portal and the apex.

There are two stretches of 20+ km in the Brenner Base Tunnel with no access shafts. Without building artificial islands the shortest you could do for the Irish Sea would be 29 km on the Portpatrick to Mew Island route or 20+15+20 km on the Antrim - Kintyre - Arran - West Kilbride route.

I don't see why it needs to be 3x the price. As for the comparison with HS2 - that says more about HS2 than the cost of a tunnel, once again demonstrating in this case the cartel pricing of UK construction vs Austrian or Italian.

 

[najaB]

But the Channel Tunnel hasn't even managed to drive the Dover-Calais ferries out of the market, let alonet he other crossings to Europe.

We've been here before. It was never intended to drive Dover-Calais ferries out of the market.

 

[HSTEd]

Does anybody know what the £20bn includes? Least of all BoJo? Work packages for the Brenner Base Tunnel can be seen at https://www.bbt-se.com

So the estimate is almost entirely meaningless?
Indeed the only place I've seen anyone try to justify it was a retired "offshore engineer" writing a hite piece where he forced the bridge to go to Larne.
Because avoiding a ten mile Dual Carriageway extension across open terrain justifies making the bridge several kilometres longer.

The Brenner Base Tunnel is far from flat. There is a 185m height difference between north portal and the apex.

Rising towards the centre of the tunnel makes construction much simpler.
For no other reason than water will run out of the tunnel by its own volition.
A sea based tunnel cannot do that, for obvious reasons.

There are two stretches of 20+ km in the Brenner Base Tunnel with no access shafts. Without building artificial islands the shortest you could do for the Irish Sea would be 29 km on the Portpatrick to Mew Island route or 20+15+20 km on the Antrim - Kintyre - Arran - West Kilbride route.

Those north routes are hardly very practical though are they?

I don't see why it needs to be 3x the price. As for the comparison with HS2 - that says more about HS2 than the cost of a tunnel, once again demonstrating in this case the cartel pricing of UK construction vs Austrian or Italian.

Given that the £20bn estimate is for a UK price, there being cartel pricing militates against a tunnel being far cheaper.

 

[Eddd]

Rising towards the centre of the tunnel makes construction much simpler.
For no other reason than water will run out of the tunnel by its own volition.
A sea based tunnel cannot do that, for obvious reasons.

In the absence of any existing solution to that problem, I'd suggest troughs at the sump of the tunnel and a scoop on each train. Other than that, the drainage arrangements would be no different.

 

[33Hz]

For no other reason than water will run out of the tunnel by its own volition.
A sea based tunnel cannot do that, for obvious reasons.

I hear pumps are a fairly mature technology. I believe the use them on the tunnel under the English Channel

Those north routes are hardly very practical though are they?

If the shorter legs allowed for a cheaper crossing and the main objective is to connect the Scottish Central Belt to Northern Ireland, then I don't see why it shouldn't be considered. But I agree from an English perspective the southerly route makes more sense.

Given that the £20bn estimate is for a UK price, there being cartel pricing militates against a tunnel being far cheaper.

Get the Irish to build it. They built all the other railways in this country

 

[The Ham]

If you had a freight terminal at Gretna Green (just off the M6) it would be about 100 miles to Stranraer, this should fairly easy to cut the road journey time from circa 2 hours to circa 1:15 hours by train.

For traffic from within Scotland you'd want a second line for your passengers anyway, again a journey of 1:15 vs the current 2 hours would be achievable from near Glasgow. Probably a fairly good location would be near Prestwick Airport.

Then with a cutting of the "crossing" time to, say, 45 minutes from over 2 hours that would reduce journey times by 1/2 to about 2 hours.

If you run the trains every 45 minutes from each terminal there would be 32 journeys a day each way rather than the current 12. This would require 8 trains in service (4 from each terminal)

All in all that would make the journey quicker and more frequent than the current road/ferry option. That would make it much more attractive and so would probably result in a fairly large share of the market.

Even if you provided a road option I'd guess that few would take it given the much longer drive required.

Yes it would push the costs to to build two new rail links, but if you're looking for low carbon then it would work well.

The other thing to consider would be that with electric cars they would unlikely be able to charge much on a ferry, whilst they could on a train. This would give them a much longer range over the driving/ferry option (not least the 80-100 miles which they wouldn't need to drive through Scotland).

 

[Eddd]

The whole point of a fixed crossing is that it has near zero operating costs.

This is optimistic. Such a bridge will have thousands of structural moving parts that will need inspection and maintenance, and possible replacement over the scale of decades, not centuries.

The structure will be vulnerable to shipping so as well as dedicated coastguards maybe there will be tugs on standby. And the problem is not just at surface level - there is a lot of submarine traffic in the area, which, based on incidents in recent years, is not always piloted as professionally as you might hope.

Furthermore, motorists and their vehicles are unreliable so the carriageway will need constant surveillance and supervision. Anyone outside a vehicle on the bridge will be exposed and incidents will need a rapid response, probably requiring emergency teams on standby at intermediate locations along the bridge.

You also ignore the operating costs of the vehicles using bridge. It is common for private motorists to think that the only per-mile cost is fuel. In terms of business and the wider economy, this is not true.

All the while, whoever builds it will want to service the debt raised for construction, just as the ferry companies do. The typical user doesn't care how their toll or ferry ticket breaks down between capital repayment, interest, operating costs and profit. No-one is suggesting that a bridge would repay all its costs through tolls, the implication being that tolls would only be cheaper than a ferry because of government funding.

I don't argue that a rail tunnel would necessarily be cheaper, just that it's wrong to suggest a road bridge would have negligible operating costs.

 

[HSTEd]

This is optimistic. Such a bridge will have thousands of structural moving parts that will need inspection and maintenance, and possible replacement over the scale of decades, not centuries.

The structural moving parts are a small part of the cost though, as we see on bridges elsewhere.

The structure will be vulnerable to shipping so as well as dedicated coastguards maybe there will be tugs on standby. And the problem is not just at surface level - there is a lot of submarine traffic in the area, which, based on incidents in recent years, is not always piloted as professionally as you might hope.

The simplest, and probably cheapest answer to this problem is "more concrete".

A submarine is unlikely to be able to do any significant damage to a gravity base structure with a mass that will likely be well over half a million tonnes.
The same holds less strongly for surface vessels, we see this in Hibernia which is designed to withstand the impact with an iceberg.

The extra coastguard costs will be very small indeed since they will probably require only a handful of additional navigation radars mounted on the piers themselves.

All the while, whoever builds it will want to service the debt raised for construction, just as the ferry companies do. The typical user doesn't care how their toll or ferry ticket breaks down between capital repayment, interest, operating costs and profit. No-one is suggesting that a bridge would repay all its costs through tolls, the implication being that tolls would only be cheaper than a ferry because of government funding.

In fact I would argue that tolls should be set to zero.
They aren't going to raise large amounts of money either way.

Best bet to improve public benefit is just to go all in for the connectivity benefits.

I don't argue that a rail tunnel would necessarily be cheaper, just that it's wrong to suggest a road bridge would have negligible operating costs.

So far you've suggested things indicating an on-duty staff of a dozen or so people.
4 (2x2) in recovery vehicles at each end of the bridge, two watchstanders in the Coast Guard command post watching the radar repeaters, and 2 in the traffic control centre.

That makes 8.

Even with a pair of recovery crews at mid-bridge we are looking at a crew of a dozen on duty

Any rail based solution will probably require more drivers than that, let alone all the people who will manage people performing precision (by most people's standards) driving involving maneuovering on and off the trains.