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

Shedite27

https://www.boards.ie/discussion/comment/119856875#Comment_119856875

What do you think would cause the blockage at Dunkettle Interchange if that's freeflow?

The Red Cow roundabout that has far higher car volumes rarely backs up nowadays.

AugustusMinimus

https://www.boards.ie/discussion/comment/119857036#Comment_119857036

Traffic could queue and backup from the Dunkettle Roundabout in Tivoli. We’re talking about 2 different roundabouts by the way. Dunkettle Roundabout causing trouble for the Dunkettle Interchange.

Chris_5339762

What I mean is in the new temporary arrangement - where the lights are still in place and the "half slip" from the Dunkettle Interchange to N25E that will be opening soon. By the looks of the new gantries, they'll be telling people for now to get into the left lane for both Tivoli and N25E coming out of the tunnel, which will be awful in terms of jamups in the evenings.

I don't think there'll be a problem with traffic backing up from the Dunkettle Roundabout to the Dunkettle Interchange.

KrisW1001

https://www.boards.ie/discussion/comment/119856780#Comment_119856780

Not my estimation. The traffic flow figures that were used to design the interchange were posted here a long while back. I don’t see how you can increase the capacity of a system that’s already dealing with current demand and by doing so somehow break it.

If necessary, there's room to add another lane to the Dunkettle roundabout, and provide dedicated slip for N25-to-Tivoli and N8-to-Glanmire. That would increase the capacity of the junction, but the traffic lights are staying no matter what is done. The goal is to accommodate the traffic and allow space for drivers to sort into their correct lanes and take their correct turns further in. The traffic lights are part of meeting that requirement. If you take the lights away from Dunkettle roundabout, you will just end up bunching the traffic up in Glanmire and especially at Tivoli. Grade separation is also no use here, as it won’t magic up more road capacity in Tivoli or Glanmire.

Long term, the answer for congestion at Tivoli and Glanmire is N40 North Ring.

marno21

Long term, the answer for congestion at Tivoli and Glanmire is N40 North Ring.

This. Remember the port traffic will also soon be out of the equation here and the Dunkettle -> N20 traffic then becomes part of the M8 flow.

This is so far into the future though we may as well plan for it never happening.

hans aus dtschl

https://www.boards.ie/discussion/comment/119857251#Comment_119857251

Yes I don't see the traffic lights at Dunkettle going anywhere soon.

If Dunkettle free-flow were to happen, it could only be in conjunction with the complete redevelopment of a sustainable route on the same corridor, and then effectively blocking and diverting that traffic into P&R's and ring-roads.

It seems more likely to me that the N28 from Dunkettle to Tivoli becomes downgraded from 100kmh 2+2. This stretch is a very serious impediment to sustainable transport in the East of the city and work is underway right now to try and remedy it to some degree. At least 2 projects are working on it simultaneously. And Tivoli is still industrial and will be undeveloped for a nice long while yet. There's factories and all sorts of stuff in there.

For that reason I don't see Dunkettle roundabout becoming free-flow with a motorist priority any time soon and possibly never. Adding another lane and making it free-flow would directly work against the effort to get people to cycle between Glanmire/Glounthaune/Carrigtohill and the city. I believe they'll try and get a pedestrian/cycle route and bus route on that corridor as the next highest priority. Then the following priority will be development of the Tivoli area, likely with a P&R.

If the Dunkettle lights cause the breakdown of traffic in the tunnel then that's just unfortunate and, just like others have said, the solution for M20-N28 traffic must be a new Northern Distributor followed by a N40 North. I'm not one to sing for "more new roads" but I'm saying Dunkettle Roundabout free-flow upgrade is a no-no compared with an N40 North. Bringing articulated trucks through the Glen and down Silversprings is already not ideal. But additionally making traffic between city and suburbs free-flow is definitely undesirable.

Again, banging the same old drum over and over, but the priority for N40 and N8 traffic issues will be getting people out of cars where possible. And for clarity, I'm not going down the tree-hugging route of "nobody should drive", I'm just saying that some people definitely will, if you make it safe and fast for them (segregated/direct for cyclists, frequent/cheap for mass transit).

cork_south

New road north west of the tunnel almost fully surfaced now. New retaining wall is plush with existing tunnel wall now also.

KrisW1001

Yep. I think we'll see Tunnel-Tivoli and Tunnel-N25 East (green line in pic below) opening soon.

[EDIT: the rest of this was wrong, see comments below]

AugustusMinimus

https://www.boards.ie/discussion/comment/119861178#Comment_119861178

That’s not quite correct.

Tunnel to M8 will be moved eastwards and will go under the current N25 under where it says DKI Rndt.

The orange line you drew will only carry N25 east to M8 north movement traffic.

marno21

https://www.boards.ie/discussion/comment/119861178#Comment_119861178

N40N -> M8N will be going under the eastern side of the flyover, as per diagram below:

The slip that'll be going over the bridge you have highlighted in orange will be N25W -> M8N.

KrisW1001

My mistake previously, apologies.

So, we’ll soon have two of the movements from the tunnel (City, the pink line below; and N25 East, the light-green line) done, but It'll take a while before we’re ready to do the third, Tunnel-M8 (orange line), as this will need the removal of traffic from the section shaded in blue, below

AugustusMinimus

https://www.boards.ie/discussion/comment/119861209#Comment_119861209

Were these drawings ever presented for the other options which were put on the table. I remember seeing them and thinking the movements were very hard to follow.

Chris_5339762

Loads of information in this weeks newsletter but basically they are hoping (weather permitting) to open the following by the end of November -

Link E: M8S to N25E

Link A: N40N to N25E ***

Link G: N40N and M8E to the new Little Island junction

Link B: N40N to Tivoli

*** They aren't very prescriptive about this one, I think it won't be a freeflow opening myself YET as they can't remove traffic lights just yet (not until Tivoli - N40S is done and that sliproad onto the roundabout closed, as well as other parts of the Little Island junction done to allow M8S to Tivoli to divert via the junction) and in the short term they want all traffic going N40N to N25E to be in the left lane going through the tunnel which I believe will cause absolute pandemonium. I hope I am wrong!

AugustusMinimus

https://www.boards.ie/discussion/comment/119863399#Comment_119863399

They can’t remove lights at the tunnel exit until the N25 West to M8 north movement is taken off the roundabout. The set of lights on the roundabout before the M8 exit will be removed though when N8 East to Tunnel opens.

Mushy

Link B, the tunnel to city link, will that have lights now?

Chris_5339762

https://www.boards.ie/discussion/comment/119863534#Comment_119863534

Forgot about that one, but I don't think its a game changer... N25W to M8N could be done via a loop at the Glanmire Roundabout and back on yourself to the newly opened Tivoli to M8N slip. Quite how chaotic that would be though, I don't know.

AugustusMinimus

https://www.boards.ie/discussion/comment/119863660#Comment_119863660

I think that will be the solution to facilitate the movement between closing the roundabout and opening the full slip. That slip will require building a big embankment where the current roundabout is.

I think you’re right about no lights on tunnel exit at that point.

EDIT: M8 South to Tivoli will also need to be facilitated. This will happen when the dumbbell fully opens.

Jaffleywaffley

https://www.boards.ie/discussion/comment/119851077#Comment_119851077

There are now two gantries on the N40 (after Mahon) with these signs before the tunnel. They are signed with an arrow left for Cork, left lane for N25 and right lane for N8/M8 etc. (N25 and N/M8 greyed out at the moment)

I feel like if someone took the left for Cork literally then they'll drive up the tunnel service building lane rather than realising that the left turn meant after the tunnel.

Maybe I'm just being pedantic 😂 but it just struck me as odd!

Risoc

no, that occurred to me aswell today.

They also have a roundabout sign before the tunnel saying n25 is third exit. That will have to go/be amended in the coming days.

markodaly

Seems the project is progressing well. How many more links and slip roads are to be opened up, once we get those ones opened up this week?

As an aside, is there any news on the Dunkettle train station and P+R? Is that still going ahead?

hans aus dtschl

https://www.boards.ie/discussion/comment/119877116#Comment_119877116

The original version of that is dead and buried now. They wanted the space immediately to the NE of the interchange, between North Esk and the Tunnel Roundabout. This has now been consumed by the interchange upgrade.

However, a "Dunkettle P&R" still exists in CMATS.

Cork Rail.PNG

Some space exists to the NE of the interchange which could be CPO'd but I don't believe that to be likely. The next available space (North Esk depot itself) is a few hundred metres from Little Island train station, which is set to be upgraded as it will likely be an "interchange" type train station for Midleton/Cobh/Mallow services.

My prediction: Dunkettle P&R will be quietly dropped, and Little Island and the "future" development of Tivoli will have a P&R. I have no insider info whatsoever though.

markodaly

https://www.boards.ie/discussion/comment/119877565#Comment_119877565

Possibly.

Keep the Dunkettle station plans but move the P&R aspect to Little Island where there is more space.

I guess we will see in due course.

AugustusMinimus

3 followings link roads pencilled in to open on Sunday 20 November at 11.00am subject to weather conditions.

Link A: Tunnel to N25 east

Link E: M8 South to N25 East

Link G: Up ramp from Links A and E to the dumbbell interchange.

serfboard

https://www.boards.ie/discussion/comment/119881656#Comment_119881656

Sorry now to re-open this, but, as a non-local, I'm looking at the maps again and wondering about the need for Link G at all, given the potential collision implications. Could Little Island-bound traffic not get off at Junction 2 on the N25, and then double-back on the local roads if necessary? Or is it the Irish Rail Terminal at North Esk that's driving this?

AugustusMinimus

https://www.boards.ie/discussion/comment/119881774#Comment_119881774

Link G will also facilitate the M8 South to City Centre main line movement.

hans aus dtschl

And M8 South to Little Island. Which is a surprisingly busy one (Little Island is a big employment centre with a lot of car and HGV traffic). It's needed alright I'd say.

The other thing is that Little Island Junction 2 is very much oversubscribed at present. The Council resorted to narrowing the footpaths to get another traffic lane in, two years ago. But even that horrendous job is only "fingers in the dam" because they'll urgently need to signalise the crompán roundabout (the "dumbell" Roundabout immediately to the South of Junction 2).

I know I know, I always go on about sustainable transport, but currently people literally run across a two-lane roundabout, after getting off the train. It's insanity.

And then on top of that, bus companies frequently complain that the lack of priority makes bus transport on the island a waste of effort. So the general plan is to use one of the 2 lanes on each of the junctions to provide a bus "loop" through the island, linking the city, train station and business parks.

So anyway, sorry for the long post but...

TLDR: you can't get more traffic into Junction 2. You probably will soon see less traffic going into Junction 2 and reasonably significant changes to the road network there. So the hope is that the new link G can alleviate the associated stress on that junction.

gooseman12

Its not clear from the email if along with the 3 new openings they are also closing the existing slip from the roundabout onto N25 East, ie if you miss the new link A you still have somewhere to go without going the whole way around again.

Either way, there's probably going to pandemonium first thing on Monday morning as I'm not sure that many people are very aware of these somewhat major layout changes.

Its time to put those expensive gantry signs to use and highlight the changes over the next few days so people know

https://www.boards.ie/discussion/comment/119881656#Comment_119881656

AugustusMinimus

https://www.boards.ie/discussion/comment/119882623#Comment_119882623

Almost certain that the old slip will be closed as construction will need to begin on the loop for the City to Tunnel movement.

Those who are in the wrong lane can go around the roundabout and circle back for now. I expect a big media campaign in the coming days.

Agree though. The roundabout might be chaos on Monday morning.

Chris_5339762

https://www.boards.ie/discussion/comment/119882623#Comment_119882623

It's not clear, but I hope they do close it. Then they can build N25E to N40S loop with that closed, and at that stage Link A (N40N to N25E) can actually be made freeflow. M8S to Tivoli can route via the new Link G, the new bridge, and Little Island for now.

I'm still predicting chaos on Monday evening as all N40N to N25E traffic is being told by the gantries to get into the left hand lane only... effectively halving the capacity of the main movement on the south ring through the tunnel, which I still think will be utter pandemonium. But we'll see. Sadly I'm in work Monday.

AugustusMinimus

https://www.boards.ie/discussion/comment/119883410#Comment_119883410

At present. Tunnel exit has 4 lanes.

Lane 1: City Centre and M8 north

Lane 2: M8 North and N25 east

Lane 3: N25 east

Lane 4: N25 east and Little Island

I think the new N25 slip may begin with 2 lanes. Hence new lane setup at tunnel exit:

Lane 1: City Centre and N25 east

Lane 2: N25 East and M8 north

Lane 3: M8 north

Lane 4: Little Island