HS4 and a rail lik from Britain to Ireland

[Indigo Soup]

A number of ferry companies operate wet leases - that's an airline term for renting fully crewed and ready to fly planes. Ships are generally wet underneath so the term might not be the same.

In maritime leasing terms, you're talking about a time charter. The equivalent to a 'dry lease' is a bareboat charter. There's also voyage charters, which are akin to charter flights.

Also worth noting that unless it would be possible to make an HSS train ferry, this wouldn’t give a through service.

There's no obvious technical reason why you couldn't build a very fast train ferry. The mechanics of getting the trains on and off would probably kill the turnaround times, so the economics would be awful.

We could revert to ferries going to Stranraer Harbour instead of Cairnryan and to Dun Laoghaire instead of Dublin docks, and Larne instead of Belfast harbour. All three were great for rail links - but the road won out over the last 20 years, and now rail connection is not there any more.

That's only going to work if you force the ferry companies to do it. And probably provide strong disincentives to people travelling with their own cars. Getting to the ferry by rail only works for foot passengers, and ferry companies realised quite some years ago that the cheapest way to handle the small remaining numbers of foot passengers is by bus. A few operators don't even have passenger boarding facilities any more - they just drive a bus into the vehicle deck to offload foot passengers.

 

[Technologist]

A bridge with an enclosed lower deck, such as is provided on bridges in Hong Kong, would provide just as good an access as a tunnel would have in any weather.

Most likely not, it would impose major restrictions on the ampacity of the connection due to the difficulty of cooling.
The capacity of a surface connection integrated into a bridge would be much greater than that in a tunnel for this reason.

Worth noting that those were the P95 prices with lots of optimism bias, and that the bridge option was a combined road-rail bridge rather than a rail-only tunnel.
Both options spent an awful lot of money on rail infrastructure that wasn't on the bridge/tunnel.

Indeed the rail connections alone cost two-thirds as much as the bridge itself.

These studies and similar are part of the root of what is wrong with UK Industry, construction and the railways.

Meanwhile in Norway they have long term plans to drive a 1000km highway across multiple fjords to improve connectivity to a city on the end point which is the size of Derby! The largest city on the route is the size of Hull and yet they are looking at submerged floating tunnels, the worlds longest suspension bridge and tunnel/bridge hybrids.

The key issue with construction in the UK (£100m bat tunnels aside) is that our construction sector has small atomised companies who are entirely project focused and filled with sub contractors rather than IP holding and generating companies/authorities.

Norway has the long term goal to build that costal highway and rather than dismiss it as impossible or uneconomic they work at developing the solutions over time to make it economic. If you demand that a project has to make sense today with existing capabilities/assumptions you will never do anything until decades after other places have done it and you will make a pigs ear of doing it when you get around to it. Hence Norway have already built the worlds longest under water road tunnel as part of this scheme for a relatively tiny cost compared to much less ambitious projects in the UK. They have done this with much better paid people too.

Basically you need to do more R&D upfront and you need to be able to make change decisions during the project faster. Compare and contrast the tale of two space towers, NASA's mobile launch tower for its SLS program that has cost billions and is years late vs SpaceX who have built 2 towers capable of catching a rocket booster in a few years with continuous design changes all the way through. The SpaceX one was built quick because they intensively plan in the short term but only have an outline direction in the long term and an annual budget.

Ireland is a rich and under populated country, they could accommodate a vastly greater number of people. The potential for linking the M62 belt of UK cities and Dublin and Belfast into a single region with 2 hour transport between them is absolutely massive. I would suggest that if you built a floating tunnel or bridge directly across from Holyhead, you'd get to the point where you'd see significant economies of volume producing a standardised tunnelling system, which you could then use to do a Belfast to Glasgow/Edinburgh arc.

 

[MarkyT]

There's no obvious technical reason why you couldn't build a very fast train ferry. The mechanics of getting the trains on and off would probably kill the turnaround times, so the economics would be awful.

Pretty quick on the old Rodby-Puttgarden ferry, just roll on roll off on the same linkspan as the HGVs/road coaches. No slower than the equivalent length of road vehicles I'd say. Rail on this ferry ceased in 2019 though, to be replaced eventually by a new tunnel link. Irish sea tidal range would make designing a linkspan suitable for rail at all times far more tricky. The Baltic, as an enclosed basin by contrast, has very little tidal range, only a few centimeters.

That's only going to work if you force the ferry companies to do it. And probably provide strong disincentives to people travelling with their own cars. Getting to the ferry by rail only works for foot passengers, and ferry companies realised quite some years ago that the cheapest way to handle the small remaining numbers of foot passengers is by bus. A few operators don't even have passenger boarding facilities any more - they just drive a bus into the vehicle deck to offload foot passengers.

I think Stranraer was becoming difficult for the largest modern vessels.
The best way to get more passengers out of their private cars on the GB-Ireland axis is to improve public transport links to appropriate airports.

 

[Ghostbus]

The big question is, what impact might the next generation of airships have on the GB/EU to Ireland freight market, and how much might it add to a passenger/car ferry ticket?

If the airships are autonomous, weather resistant, green powered and can carry 10 or 20 shipping containers with landings and takeoffs every few minutes at a network of inland ports connected to road and rail, then that is likely the final nail in the coffin of any proposed bridge or tunnel.

So then we just wait for Hyperloop......

 

[D365]

I thought it sounded odd! Ampage, surely?

In my day jobs it’s just ”cable rating”.

 

[fishwomp]

That's only going to work if you force the ferry companies to do it. And probably provide strong disincentives to people travelling with their own cars.

.. and that won't work: people put cars on ferries for a reason!

Getting to the ferry by rail only works for foot passengers, and ferry companies realised quite some years ago that the cheapest way to handle the small remaining numbers of foot passengers is by bus.

Yep. It goes like this: build a port add railway line, add road, add water. Wait 150 years. Port is now a town of supporting industry with traffic. Solution: Move port. Move road. Repeat (without rail). Cairnryan is at the early stage you could say.

A few operators don't even have passenger boarding facilities any more - they just drive a bus into the vehicle deck to offload foot passengers.

Most I think. That's how Rosslare and Dublin work, along with Pembroke and Holyhead. Last time I did Fishguard you could walk on - it might have had a bus drive on and pick up at Rosslare. Sadly there is no foot pax option on the Dublin to Liverpool.

I think Stranraer was becoming difficult for the largest modern vessels.
The best way to get more passengers out of their private cars on the GB-Ireland axis is to improve public transport links to appropriate airports.

The other thing is that Cairnryan lets them offload traffic 15 mins sooner than Stranraer - so improving journey times for vehicles, and a fast coach to Ayr improves rail connection too, except for people like me who would avoid a coach and just enjoy the track.

 

[SynthD]

There's no obvious technical reason why you couldn't build a very fast train ferry.

I would love to see a video of trains on a boat moving fast enough to be buffeted by the waves it drives into. If it’s as obvious as I’m imagining, HSE might not like it.

A few operators don't even have passenger boarding facilities any more - they just drive a bus into the vehicle deck to offload foot passengers.

Based on what I know, I don't think the public are aware of this. Stenaline only do this at two of their GB mainland ports. https://www.stenaline.co.uk/customer-service/at-the-port/how-do-foot-passengers-access-the-ferry

I would suggest that if you built a floating tunnel or bridge directly across from Holyhead

Could you identify a Norwegian fjord the width of the Irish Sea, for comparison?

 

[Indigo Soup]

Pretty quick on the old Rodby-Puttgarden ferry, just roll on roll off on the same linkspan as the HGVs/road coaches. No slower than the equivalent length of road vehicles I'd say. Rail on this ferry ceased in 2019 though, to be replaced eventually by a new tunnel link. Irish sea tidal range would make designing a linkspan suitable for rail at all times far more tricky. The Baltic, as an enclosed basin by contrast, has very little tidal range, only a few centimeters.

Yep, tides make it all far more complicated. Next to no tides in the Baltic or Mediterranean. Rail's requirement for much shallower gradients than road vehicles means you need a longer linkspan. You also need more accuracy in the connection, because the rails have to line up. I'm guessing the one you refer to was designed to meet the more demanding requirements for rail - and then road vehicles used the rail linkspan.

You also have to consider disassembling and reassembling the train, not particularly challenging but potentially time consuming - especially if you're breaking a long train into three or four sections to get on the ferry.

Added to which, high speed ferries generally only have linkspans at the stern, which will slow port operations down.

.. and that won't work: people put cars on ferries for a reason!

The only way you can do it is to use the stick, instead of the carrot. But then, you just lose the traffic instead of people leaving the car behind.

I would love to see a video of trains on a boat moving fast enough to be buffeted by the waves it drives into. If it’s as obvious as I’m imagining, HSE might not like it.

That's a pretty trivial problem; trains need lashed down anyway (they roll!) and by the time the lashings are having problems, you've cancelled the sailing.

 

[MarkyT]

I would love to see a video of trains on a boat moving fast enough to be buffeted by the waves it drives into. If it’s as obvious as I’m imagining, HSE might not like it.

Besides that, even for road vehicles, current fast ferry operations are seasonally limited, typically only offering service between April and October. I assume this is mostly down to weather conditions. While there are calmer days in winter on which they might be able to sail, they're not frequent enough to offer a reliable regular service. Summer only no doubt makes commercial sense for the ferry operator who will have more leisure custom in the summer months they can offer a more attractive product to, and they can handle the volume efficiently with a fast round trip. For trains on HS ferries and year-round operations, there'd have to be a back up rail-equipped traditional ferry for days the HS vessel couldn't sail, and a clause in booking conditions about journey time occasionally being extended by two or more hours due to weather.

Yep, tides make it all far more complicated. Next to no tides in the Baltic or Mediterranean. Rail's requirement for much shallower gradients than road vehicles means you need a longer linkspan. You also need more accuracy in the connection, because the rails have to line up. I'm guessing the one you refer to was designed to meet the more demanding requirements for rail - and then road vehicles used the rail linkspan.

It was once a busy rail freight route, all diverted via Odense now since that became a through rail route, albeit a long way round.

You also have to consider disassembling and reassembling the train, not particularly challenging but potentially time consuming - especially if you're breaking a long train into three or four sections to get on the ferry.

The Danish were good at that, even splitting multi-unit passenger trains up (slowly) on the move as they approached the linkspan to be directed to their appropriate roads onboard.

 

[Indigo Soup]

Summer only no doubt makes commercial sense for the ferry operator who will have more leisure custom in the summer months they can offer a more attractive product to, and they can handle the volume efficiently with a fast round trip.

That requires the ferry operator to have a winter use for the ship - and one that isn't profitable during the summer. There's a lot of capital tied up in a ship, especially a high performance one, and the shipowner is going to want to keep it working hard.

Which is also why the 'backup' conventional ferry needs to be gainfully employed all year - so you're now running two-ship service with incompatible ships.

 

[Technologist]

Could you identify a Norwegian fjord the width of the Irish Sea, for comparison?

Why would this make a difference?

If we went for a floating tunnel the point of difficulty is always likely to be where it approaches land and you have issues like tidal currents and ranges.

In open water the tunnel is just endless replication of standard components with the only variable being what the anchor is set in and the length of the cables.

 

[MarkyT]

Why would this make a difference?

If we went for a floating tunnel the point of difficulty is always likely to be where it approaches land and you have issues like tidal currents and ranges.

In open water the tunnel is just endless replication of standard components with the only variable being what the anchor is set in and the length of the cables.

Safe egress via cross-passage to parallel running or separate service tube in an emergency is probably not as assured as with a deep below seabed concept. An 'event' in open water damaging one watertight tube may be more likely to also damage the escape route than when each is surrounded by many metres of hard rock. Norwegian links across deep fjords will have much smaller distance and time from any point to safe exits. Tidal range is small in Fjords but they can suffer from significant Tsunami effects of major rock or glacier ice falls. A major event occurred in 1934 in Tafjord, resulting in an initial 64m wave moving at 160 km/h, causing damage up to 50 km away and resulting in forty deaths. Only 11 of the bodies were ever found.

https://www.fjords.com/rock-avalanches-tafjord/

More recently in 2023, Greenland's Dickson Fjord suffered a major Tsunami with an initial backsplash wave from the rock and ice fall of ~200m, followed by waves of ~110m whose propagation was recorded 72km away. Analysis of the rockfall suggested the failure occurred because a retreating glacier no longer buttressed a major section of rock. The affected valley was fortunately uninhabited.

The 16 September 2023 landslide at Dickson Fjord in Greenland

On 16 September 2023, a 25 million cubic metre landslide occurred on the margin of Dickson Fjord in Greenland.

eos.org

 

[zwk500]

I think there have been serious bridges built on floating supports, but has Norway (or anywhere else) actually built a floating tunnel, of either buoyancy?

 

[HSTEd]

I don't see why you'd bother with a floating tunnel for the Irish Sea - its the sort of thing only needed for very deep, very long crossings.

The Norwegian coastal highway project has numerous likely more suitable concepts - like bridges with gravity base structure towers (in one case they are proposing a tension leg platform bridge tower in 1200m of water!).

Building a bridge in even 300m of water in Beaufort's Dyke is well within our technical capability.
A viaduct in <100m water in the central Irish Sea is not an insoluble engineering problem.

 

[Indigo Soup]

A viaduct in <100m water in the central Irish Sea is not an insoluble engineering problem.

Honestly, it's not even 'not insoluble'. You could put out the tender today and probably get half a dozen bids with relevant experience of (a) bridge construction and (b) deep water structures. You wouldn't like the price tag associated with any of them, but the only thing that's really difficult about it is the scale.

You'd probably be thinking a suspension bridge with ~50 spans of 1.8 to 2 kilometres, 70-75 metres clearance at mean high springs, with gravity base or piled jacket structures. Water depth, span, clearance and subsea structure load are all within state of the art.

You might want an artificial island or two, primarily for emergency services & turnback facilities, but also as an opportunity for rest breaks and fleecing tourists (duty free?) shopping. Manage traffic in such a way that there's never queuing on the bridge.

 

[MarkyT]

I think there have been serious bridges built on floating supports, but has Norway (or anywhere else) actually built a floating tunnel, of either buoyancy?

There are some impressive floating bridges around Seattle, one of which recently gained a new light rail line. The submerged floating tunnel is an aspiration only so far I believe in Norway, proposed as one candidate solution for numerous fjords a major new trunk road needs to cross to follow the coastline. It's a particular issue in fjord landscapes where sea has flooded major glacial valleys because they can be so deep below water level relative to their width.

 

[Pigeon]

I thought it sounded odd! Ampage, surely?

Amperage.

There's no obvious technical reason why you couldn't build a very fast train ferry. The mechanics of getting the trains on and off would probably kill the turnaround times, so the economics would be awful.

The point there is that the (assumed) mechanics of getting the trains on and off would greatly increase the total transit times, ie. for the trains themselves, thus making the thing "very fast" in merely getting across the sea isn't very useful, even if you go to such extremes as making an ekranoplan instead of a displacement vessel. In any case, you don't want to go "very fast" because the fuel consumption goes through the roof. The thing to do is use ingenuity rather than brute force and ignorance, and achieve a decent total transit time by devising a mechanism for getting the trains on and off in say under 5 minutes between being parked on the ferry and running clear on the main line, while only going reasonably fast in crossing the sea.

 

[Tetragon213]

I don't see why you'd bother with a floating tunnel for the Irish Sea - its the sort of thing only needed for very deep, very long crossings.

The Norwegian coastal highway project has numerous likely more suitable concepts - like bridges with gravity base structure towers (in one case they are proposing a tension leg platform bridge tower in 1200m of water!).

Building a bridge in even 300m of water in Beaufort's Dyke is well within our technical capability.
A viaduct in <100m water in the central Irish Sea is not an insoluble engineering problem.

Beaufort's Dyke, however, happens to also to be the final resting place of a truly jaw-dropping amount of waste ammunition.

After WWII, we threw a lot of our (now surplus) ammunition into the waters off Cairnryan... into Beaufort's Dyke. The MOD estimates something on the order of 1x10^7 tonnes of munitions of all varieties, the most alarming of which are the ones filled with varying combinations of phosgene, mustard gas, white phosphorous, and god knows how much Amatol, Torpex, Cordite, etc.

 

[HSTEd]

Beaufort's Dyke, however, happens to also to be the final resting place of a truly jaw-dropping amount of waste ammunition.

After WWII, we threw a lot of our (now surplus) ammunition into the waters off Cairnryan... into Beaufort's Dyke. The MOD estimates something on the order of 1x10^7 tonnes of munitions of all varieties, the most alarming of which are the ones filled with varying combinations of phosgene, mustard gas, white phosphorous, and god knows how much Amatol, Torpex, Cordite, etc.

Yes, but only a tiny portion of the area would have to be cleared in order to ground out the gravity base structures required to support the crossing.
Even if we assume any of these weapons is capable of meaningfully damaging a bridge tower weighing hundreds of thousands of tonnes, the only area that would have to be swept is the area which the supports would physically occupy. The vast majority of the dump could be left where it is.

 

[zwk500]

Yes, but only a tiny portion of the area would have to be cleared in order to ground out the gravity base structures required to support the crossing.
Even if we assume any of these weapons is capable of meaningfully damaging a bridge tower weighing hundreds of thousands of tonnes, the only area that would have to be swept is the area which the supports would physically occupy. The vast majority of the dump could be left where it is.

That does nothing for land connections either side, which are likely to need to be motorway or at least HQDC standard if the volume of traffic using the bridge is going to make economic sense.

 

[HSTEd]

That does nothing for land connections either side, which are likely to need to be motorway or at least HQDC standard if the volume of traffic using the bridge is going to make economic sense.

Well that is unlikely to be somethng we cannot build, as opposed to merely asking whether it is worth building.

At the moment building dual carriageways does seem to be much cheaper than building railway lines.....
It's about 130km along the A75 to the M74.

You are unlikely to need very much road infrastructure on the NI side, as far as I can tell.

 

[Bald Rick]

At the moment building dual carriageways does seem to be much cheaper than building railway lines.....

Oh I dont know about that. A428 Black Cat to Caxton Gibbet, along some of the easiest terrain you can find, is clocking in at over £100m / mile. Not HS2 territory, but EWR (on similar terrain) is somewhat cheaper.

 

[Pigeon]

Yes, but only a tiny portion of the area would have to be cleared in order to ground out the gravity base structures required to support the crossing.
Even if we assume any of these weapons is capable of meaningfully damaging a bridge tower weighing hundreds of thousands of tonnes, the only area that would have to be swept is the area which the supports would physically occupy. The vast majority of the dump could be left where it is.

No, you don't want to clear any of it. You don't want to go anywhere near it. Some of the explosives will have become highly unstable due to reactions with the metal they are enclosed in and suchlike while underwater, and once one thing goes bang the shock wave will set the rest off. Which you don't want to happen because there's enough down there to make a nuke-sized bang and the surrounding coastal settlements will not be happy.

 

[HSTEd]

No, you don't want to clear any of it. You don't want to go anywhere near it. Some of the explosives will have become highly unstable due to reactions with the metal they are enclosed in and suchlike while underwater, and once one thing goes bang the shock wave will set the rest off.

There is no plausible mechanism for a significant chain reaction.

Doing stuff on the seabed in that environment was apparently considered low enough risk that they built a gas pipeline straight through it (map on page 8/68)!
And that will have required far more clearance of the seabed than a handful of bridge towers.

 

[Tetragon213]

There is no plausible mechanism for a significant chain reaction.

Doing stuff on the seabed in that environment was apparently considered low enough risk that they built a gas pipeline straight through it (map on page 8/68)!
And that will have required far more clearance of the seabed than a handful of bridge towers.

And the construction of that pipeline ended up digging up incendiary bomblets from the seabed, and strewing them across the beaches of Scotland...

Some four y/o kid ended up getting burned while playing on the beach when the phosphorous within an aforementioned bomblet went off.

 

[Indigo Soup]

Some four y/o kid ended up getting burned while playing on the beach when the phosphorous within an aforementioned bomblet went off.

Notably, there is a significant difference between 'one four-year-old child got burnt' and 'mass destruction of coastal settlements'. Safe clearance of the limited area affected by bridge construction wouldn't be prohibitively difficult. Especially because any remotely competent engineers would avoid putting the subsea structures in areas with a high concentration of UXO.

For what it's worth, the Union Connectivity Review's proposed bridge was to have 4km spans, allowing one pier either side of the deep water, with the bridge pylons designed with the UXO risk in mind.

 

[corfield]

There is no plausible mechanism for a significant chain reaction.

Eh?

We have libraries of policy on explosive safety, all written in blood.

Chain reaction has an exceptionally plausible mechanism. Hence why preventing it forms the basis of most of that policy and the management of explosive safety.

 

[HSTEd]

Eh?

We have libraries of policy on explosive safety, all written in blood.

Chain reaction has an exceptionally plausible mechanism. Hence why preventing it forms the basis of most of that policy and the management of explosive safety.

Perhaps I should have clarified, there is no plausible mechanism for a significant chain reaction in the context of material at the bottom of Beaufort's Dyke.

 

[corfield]

Perhaps I should have clarified, there is no plausible mechanism for a significant chain reaction in the context of material at the bottom of Beaufort's Dyke.

The 1986 explosion suggests otherwise. A mere 2.5 or whatever it was Richter wise but is that the tip of an iceberg?

As does pretty much all other instance of explosives “stored” adjacent to each other.

Plus the risk wrt Beaufort is less explosions and more about highly toxic pollution. Otheriwse we’d just initate it and stand well back. Even then the risk of stuff not going but remaining at risk of that would be very high and the survey difficulties exacerbate all of it.

Short of a massive clearup, the costs of which would be truly eye watering, if even feasible given the scope for toxic chemicals release even with remotes etc, it seems best to do as my instructor advised if people mess with explosives: go somewhere else, and keep going!

Of course the converse is also true, it can be hard to get things to go bang, at least wrt detonation vs deflageration. That’s worse though because you don’t know where the line is until you cross it!

 

[Meerkat]

The answer is amphibious trains. I’ll leave the details to the Bond film producers engineers.