[N25] Jack Lynch Tunnel construction pics

Chris_533976

I remembered this the other day. A few years ago I did a school project documenting the construction of the Lee Tunnel in Cork. So today I decided to scan in all the pics I took as some people on here might find them interesting. Some are photos I took, others are ripped from documentation I was sent.

Heres plenty of background information -

http://en.wikipedia.org/wiki/Jack_Lynch_Tunnel

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Night image of tunnel segments under construction -



Ariel view of tunnel segments under construction -



More tunnel basin construction pics -





Ariel view of tunnel segments being floated into place -



Mahon approach road several months before tunnel opening -



Dunkettle entrance a few months before opening -







Gantry supports in place -




This process is effectively being paralleled in the Limerick Tunnel at the moment.

Fooz

Good stuff! Very interesting.

embraer170

Great post, thanks!

invincibleirish

am i not correct in thinking that firstly the tunnel is at or near its capacity which wasnt meant to happen for another decade and that traffic is only going to get worse at the dunkettle interchange?

Chris_533976

Dunkettle interchange is backed up about a kilometer eastbound in the mornings and 1-2km westbound in the evenings. When the Sarsfield and Bandon road roundabouts are done it will get much worse, then when the North Ring is done it will be a disaster zone.

Plus as far as I know there are no plans at all to grade seperate it. Theres nothing on the NRA website and that goes to about 2015.

It would be a bastard of a thing to fix too, as theres little space, a tunnel, a lot of water, a future P&R (which will get in the way as they wont think to plan around a grade sep), an old Demesne and a river in the way.

Its a bad bottleneck at the moment, and once the M50, Newlands etc are all done this will be known as the big one.

1huge1

I'm doing something of the same actually with the Limerick tunnel, so far its looking very impressive, longer than the jack lynch tunnel but will sadly be tolled, biggest infractural project ever undertaken in the state outside dublin

strassenwolf

Those are great pictures, Chris. Thanks for posting them.:)

Maybe you could answer a couple of questions about the tunnel, if you've got the time.

It was a very interesting way to achieve the crossing. From what I've read, these immersed tube tunnels are cheaper to put in place than regular tunnels, so cost presumably was a factor in using this method. Were there other reasons why this method was used in this case?

There must have been an enormous amount of earth removed during construction, both from the dredged trench and the casting basin. Have you any idea what happened to it? (The old east stand from Lansdowne Road, for example, lies under the southside access road to the east link toll bridge. Apparently much of the recently demolished stadium will be reused in the new one - though I don't know how).

There are occasional reports on the radio of the JLT being flooded. Presumably the designers of the Shannon tunnel will want to avoid this happening. Any idea what changes they're making to the design? (I've never been sure whether this occurs because water is seeping in from the river, or whether it's rainfall which is flowing down into the tunnel). And, finally, what, if anything, can realistically be done retrospectively to stop this flooding in the JLT?

Chris_533976

I've never seen flooding myself, its not the sea getting in, more likely its blocked drains inside the tunnel with rainwater building up at the bottom.

Dredged material from the tunnel location was taken a few miles out to sea and dumped. The tunnel casting basin I'm not sure of - I guess the material was moved somewhere and then moved back to fill up the basin once the tunnel was complete. The DC goes over part of the former casting basin now.

They kinda had to use immersed tube tunnels here (and in Limerick) as the tunnel wasnt long enough to use a Tunnel Boring Machine and being very silty and without many rocks, wouldnt work anyway

strassenwolf

So there's an octopus out in the Celtic Sea wondering who dropped all that rubbish over his front garden.:D

Thanks for the answers. If Dublin's eastern by-pass is ever built, you'd wonder if this might be the method that will be used.

parsi

Those pics bring back memories. It used be common to go down and have a gawk at the proceedings.