[James Shields]

I'm with you on this, but... if there were a thousand steps on the path in transforming our railways into a world class system, the Tusker Tunnel would probably come about step 943. I would say we are currently somewhere around step 27, and there are many on this board who would be less generous than I am.

But that doesn't mean we can't fantasise about what it might be like...

Up till now, gauge has never been an issue in Ireland, being an island. It might make it slightly awkward ordering rolling stock, but we muddle on. But once we have a direct connection to another railway, it's a whole new ball game. Obviously the tunnel itself would have to be standard gauge, since everything in the UK and much of Europe beyond uses it.

However, I wxpect that as with the Channel Tunnel, the tunnel would be complete before any onward high-speed links are available. This could be a problem, since the Roslare lines are all single track and not currently what you would call high-speed lines. It's possible that Dublin-Roslare will have been doubled by then, and its speed upgraded, but current passenger numbers don't make this seem very likely. In any case, I would expect that initially passengers through the tunnel will have to get off one train and onto another.

One advantage the UK had was that since its existing track network is all standard gauge, it was relatively easy to build new high speed routes in sections, linking to older track as each section was complete. Unfortunately, it's likely we'll decide to make our high-speed links to the tunnel standard gauge so trains can whisk straight in and out. This makes the piecemeal approach much more difficult, especially since there aren't two many significant population centres along the way where you might put an interchange station.

I would think the first priority would be a high-speed line to Dublin. Much has been made of the masses of freight that will be coming in through Shannon, but I can't see it being the only deep port for long. I think there could be growth in railfreight if we get serious about emissions (and build a few nuclear plants to power electric railways), but it will likely want to go all over the country not just Shannon. Freight thends to be happy enough trundling through the night, so high-speed rail is not that important for freight. Sending freight over the current network on variable gauge trucks and putting a freight depot and gauge switcher near the tunnel mouth would seem to make the most sense.

But passenger traffic is where the tunnel will succeed or fail. I can't see it getting built at all until there is a compelling case for passengers. With high-speed all the way, I would guess we're talking of an hour Dublin-Rosslare, another hour to Pembroke, an hour to Bristol and an hour to London. That's a four-hour journey, which doesn't compare too favourably with a one hour flight. If you factor in travel time to and from airports, check-in time and baggage collection time, I'd say we're talking three hours from central Dublin to central London, which claws back some of the disadvantage, but you can't deny air has the edge. The only way I can see it working is if there's a significant move away from air travel because of emissions controls and carbon tax. This isn't beyond the bounds of possibility, but it's not likely to happen any time soon. However, if air travel became less affordable and less socially acceptable (it is destroying the planet, after all), the tunnel could become a lot more urgent.

Of course when the tunnel is first built, journey times will be much slower (unless we get much better at funding and building things at the same time). Currently Dublin-Rosslare takes three hours and London-Pembroke takes over five, however both of these journeys could be improved, even on the current track. The Irish government would have a strong incentive to complete the Dublin link, but I can't see the UK government being so quick to finish a London high-speed line, considering they've been well over a decade getting fully connected to the channel tunnel (a much shorter link to a much more crucial link as far as the UK is concerned), although I'm sure there would be a significant EU contributon to the cost.

Once a Roslare-Dublin HSR line is in place, we can look further afield. A new Dublin-Belfast route would make sense. Again, Dublin-Belfast in an hour should be achievable, which would make a huge difference for travel between the two cities as well as taking a lot of traffic off the existing route, and give Belfast a direct connection to London. A new line from Roslare-Waterford-Cork would also be a possibility. Again this ought to be possible in about an hour, which would make Cork-Dublin in two hours a possibility (not bad for a fairly indirect route) and Cork-Belfast in three, and Cork-London in four.

This is all very pie-in-the sky. But sometime in the far-flung future, it might bear some resemblance to reality.