N8/N25/N40 - Dunkettle Interchange [open to traffic]

AugustusMinimus · 23-09-2022 2:27pm

https://www.boards.ie/discussion/comment/119654669#Comment_119654669

I think any piling will be for a retaining wall to the west of that bridge.

I think N8 to Glounthaune slip will definitely open. They were doing cosmetic earth works around it this morning.

Mushy · 23-09-2022 7:16pm

https://www.boards.ie/discussion/comment/119655488#Comment_119655488

Do they not need more pillars right beside the Eastern most lane as you come from the tunnel up to roundabout? Only small ones mind, but more space be needed hence the moving the traffic away from there for the machinery. Although I guess both will be needed so could do both.

Will that n8 to glounthaune slip open without the dumbell? Otherwise all that traffic has to get into little island at the junction beside the flyover.

Chris_5339762 · 23-09-2022 8:38pm

N8 to Glounthaune can open without the dumbbell - it does not depend on the link across the dumbell. Of course you wouldn't be able to use it to get to Little Island yet though. Its an extra - provided nothing is taken away all it really does it reduce traffic over the roundabout.

That said yes, theres more bridge beams to go in in that region, so I'm not sure what'll happen to it. They say there'll be an update next week, so hopefully good news.

AugustusMinimus · 23-09-2022 8:46pm

https://www.boards.ie/discussion/comment/119657108#Comment_119657108

Beams over that section of slip road are now complete. Assume they can lay the bridge surface after opening the slip?

Mushy · 24-09-2022 8:02am

https://www.boards.ie/discussion/comment/119657108#Comment_119657108

Of course that makes sense, cos it's to glounthaune and not little island. And it means that traffic avoids the lights on the existing flyover. Not long till its all known anyway, from the email it sounded like there's a lot to happen

rameire · 28-09-2022 8:35am

looking like the Lights are not operational on the North side of the interchange between the M8 coming south and the traffic heading east.

Back working

cork_south · 28-09-2022 10:00am

Will the soon to be opened slip road coming from the Midleton direction to tunnel south bound be free flow?

Chris_5339762 · 28-09-2022 11:05am

We don't know yet, we will know more Friday in the next newsletter apparently.

My own feeling is "no", because -

Without the dumbbell being open you still need to accomodate traffic coming from the Little Island slip towards the roundabout. So you need the first set of traffic lights as you approach Dunkettle to remain.
You still need lights at the end of the new slip into the tunnel, or you'd have to do a merge which would gum everything up. Unless they put up bollards and partition it so that you freeflow into the left lane into the tunnel. But then everything else (2 lanes worth) coming off the roundabout has to filter into the right hand lane.

My own personal guess on it is that this freeflow slip is, for now, going to be part of an extension of the roundabout closer to the tunnel entrance, so they can build the rest of the N25E to M8N ramps. Extending the roundabout just makes all of those things work easily.

Much as I'd like freeflow there myself and I hope to be very wrong.

KrisW1001 · 28-09-2022 11:20am

The N25-to-tunnel slip joins the mainline to the south of the roundabout, so it could be opened as a free-flow merge. Traffic from N25 to Dublin would continue to be routed to the existing roundabout for now, though. There's a small chance of drawing it down to Dunkettle in a long U-turn in order to allow the southern sector of the main roundabout to be split, but I don't think that'll happen until the new lane on the current N8-N25 overbridge and the loop from City to Tunnel is completed (as that would allow the northern sector of the main roundabout to be split).

AugustusMinimus · 28-09-2022 12:07pm

My view:

Entrance and exit to the tunnel will be rerouted under the new bridge but will continue to use the roundabout like they did to the north of the roundabout a year ago. this will allow the embankment to be built to carry N25W to M8N north traffic as it comes off the new bridge.

Roundabout will continue to be used enough new slip roads are opened to handle traffic. I’ve drawn out a few diagrams in the past on how I think this may work.

I’m prob miles off.

cork_south · 29-09-2022 9:55am

Massive tailbacks northbound this morning as a result of the lane closure and a couple of crashes.

AugustusMinimus · 29-09-2022 10:09am

That’s to knock the retaining wall on the left as you exit the tunnel. Interested to see how long it will take.

Chris_5339762 · 29-09-2022 2:16pm

Its amazing how closing up such a small section of a slip lane is causing such problems this morning.

Not looking forward to my 6pm commute

cork_south · 29-09-2022 2:55pm

https://www.boards.ie/discussion/comment/119680521#Comment_119680521

Traffic backed up past Mahon all day according to Google maps so I'd imagine rush hour will be back to the good old days of queueing for the tunnel on the Kinsale flyover.

AugustusMinimus · 29-09-2022 7:43pm

https://youtube.com/watch?v=or0Q1yZIYX8&feature=share&utm_source=EKLEiJECCKjOmKnC5IiRIQ

Credit as usual to Drone Hawk.

Chris_5339762 · 29-09-2022 9:25pm

https://www.boards.ie/discussion/comment/119680521#Comment_119680521

In the end I went through town. Bedlam. And I still can't believe making a single slip lane 50m shorter caused all that pandemonium. I can understand some, but that was chaotic.

cork_south · 29-09-2022 9:33pm

https://www.boards.ie/discussion/comment/119682315#Comment_119682315

Yup, the whole city ground to a halt as predicted. The queue to the tunnel started near Togher and the entire South Link was blocked with people trying to chance their arm going through town.

That lane closure could go on for a long time yet.

Chris_5339762 · 29-09-2022 9:38pm

I'd say it'll be a couple of days. They'll have it done by Monday I'm guessing. Mostly because they'll be told in no uncertain terms to get it done.

AugustusMinimus · 29-09-2022 9:47pm

They are only knocking the retaining wall. It won’t take very long.

Given the queue during the day usually goes from the exit if the tunnel to the roundabout, closing the lane for only 50m or so is effectively halving the capacity of that lane.

cantalach · 30-09-2022 1:22am

It was all flagged well in advance in last week’s newsletter:

”We expect that this lane closure will be put in place from Wednesday 28th / Thursday 29th September with the initial demolition works taking 3 or 4 days to complete.”

To sign up for the newsletter: https://www.dunkettle.ie/NewsletterSignup

cork_south · 30-09-2022 8:05am

I get the newsletter and it was flagged; but flagging didn't help alleviate the gridlock unfortunately.

Chris_5339762 · 30-09-2022 12:26pm

Prizes are being given out (to me!!!) and maybe Augustus too.

[quote]

The configuration of the N25 westbound diverge approach (Link K) to the Dunkettle Interchange Roundabout will be adjusted over the coming period. The proposed new alignment in this area is shown on the layout plan attached. The existing traffic lights will be relocated to cater for the new alignment. The purpose of the adjustment in this area is to facilitate access for ground improvement works in the area immediately west of Structure St05, shown hatched on the layout plan attached.[/quote]

AugustusMinimus · 30-09-2022 1:26pm

I was off. Thought they’d have all traffic going into the tunnel go under st05.

Interesting to see if the Little Islsnd slip will remain open.

Chris_5339762 · 30-09-2022 3:23pm

They say they'll relocate the traffic lights, so I'm thinking theres little benefit to closing that slip just yet. I reckon that slip will go when the dumbbell opens fully.

DylanQuestion · 30-09-2022 4:50pm

Given the N40 has failed as a bypass, with half of the southside being outside it and it mainly serving as a distributor road, what do you guys think would be a good route for a future outer bypass (I know one would never happen)

Shedite27 · 30-09-2022 10:34pm

https://www.boards.ie/discussion/comment/119685820#Comment_119685820

Northside

AugustusMinimus · 30-09-2022 11:39pm

https://www.boards.ie/discussion/comment/119685820#Comment_119685820

I don’t think the N40 was ever planned as a bypass though. It was identified that there was a lack of West - East transit options along the south of Cork City. The South Ring Road was therefore burn with numerous at grade junctions. Only with the advent of the Tunnel did it really take on any sort of basis as a bypass. Still wouldn’t describe it as such.

N40 I wouldn’t describe as a bypass either. (Not in the Waterford or planned Galway sense. It will be an orbital ring road.

The other way to take pressure off the Tunnel / N40 would be to link the Great Island with Ringaskiddy. Would take a new tunnel or s very expensive cable stay / suspension bridge. Will never happen.

marno21 · 01-10-2022 5:39am

The only realistic route for a proper bypass would be from the Shannonpark roundabout to Ballinhassig, new motorway from there to the N40/N22 to meet the full North Ring Road. But that doesn’t address crossing the river east of the city but would take a good chunk of traffic off the N40

As Augustus said, a link from Ringaskiddy to Great Island would take a lot of pressure off the Dunkettle area but there’s simply no feasible route through that area.

DylanQuestion · 01-10-2022 10:06am

To me, the N40 is primarily a distributor road. I wonder how many of the trips start and finish within the city (i.e. Douglas - Wilton/Mahon). I agree that something like below in red would be the best. I also agree re: Waterford and Galway. I was watching back an old RTE News segment on its construction and they referred to it as an inner city bypass. But with 50,000 or so living outside the N40, a proper Southern Distributor Road is needed in my opinion. Bus Connects shows that retrofitting roads is not going to be easy, so something like the orange below (East of Rochestown - Carr's Hill M28 - Airport N27 - Wilton)

KrisW1001 · 01-10-2022 12:05pm

A variation of the western red segment might be useful as a re-routing of the city end of N71 away from the current Bandon Road, but you should to turn on the "relief" layer before you start drawing lines on a map: what you've drawn would be colossally expensive to build, as it crosses multiple deep valleys.

The whole red route serves no real purpose, though, at enormous cost. It's longer than N40/M28, which means that it just wouldn't be used by freight traffic (which is the only reason to provide a second high-capacity route to Ringaskiddy).

The orange one is a little more sensible, but really only as a distributor: an undivided road of 1 bus, 1 cycle, 1 traffic lane each way.

N8/N25/N40 - Dunkettle Interchange [open to traffic]

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