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

AugustusMinimus

https://www.boards.ie/discussion/comment/119434089#Comment_119434089

That dumbbell doesn’t need to be open to facilitate Link A or E though. You have the option on both Link A and E to join the N25 without going up to the dumbbell. The current surfacing work on the N25 is to tie these links into the N25 mainline.

cantalach

https://www.boards.ie/discussion/comment/119434227#Comment_119434227

Yes, passed through there slowly going east today and the surfacing work is all on the part of link A/E that merges onto the N25-E. They haven’t done anything with the branch off A/E that goes up to the dumbbell roundabout. In fact, it seemed to be divided off by fencing or barriers (I wasn’t going that slow). It really does look like they’re gearing up to open link E soon, possibly A too at least in a degraded form.

AugustusMinimus

https://www.boards.ie/discussion/comment/119439519#Comment_119439519

Link E ahead of link A I suspect. I think the N8 east to Glounthaune slip will also open soon.

Chris_5339762

They must have listened to me as the westbound VMS at Little Island was showing travel times instead of the "ROADWORKS AHEAD" that is actually after the start of the roadworks.

Bridge beams going in on one structure this morning westbound. Good to see.

AugustusMinimus

https://www.boards.ie/discussion/comment/119452893#Comment_119452893

Is that on structure ST02 on the south east of the junction? They highlighted this on last Fridays email.

I think we could see bridge beams on the final bridge over the M8 soon enough too given all concrete pillars now look to be formed.

DylanQuestion

https://www.boards.ie/discussion/comment/119426243#Comment_119426243

To be honest, I feel a lot of the Juntion times are useless. They are always between 2-10 minutes. The entire N40 can be driven in probably 10-15 minutes. As I said too, very few people know the junction numbers anyway. If I was them, I would only keep J1 (N22), J3 (N71), J6 (N27) and J9 (N28). The only other things needed then are City Centre, Airport, Ringaskiddy, Little Island and Dunkettle. As well as that, a lot of junctions have either no alternative routes to get to them, or else no feasible diversion routes. For example, Maryborough has N40 J6 showing. But once you pass that sign, you have no other way of going anywhere else except westbound at Bloomfield, bringing you to the opposite direction of where you want to go, as there are no off ramps between it and J6. Likewise, the Mahon times coming off the N27 going east don't mean much, as to avoid it you would need to get off at Douglas and go down Skehard Road. Or at the Togher ramps, there is no other feasible way to get to the N71 other than stay where you are. Anyway, they seem to have finalised these changes and it's looking more consistent now. Here is what they seem to be sticking with for now (a few are missing around Dunkettle as they are just warning about the roadworks)

Ballincolling (N22 before J1):

N40 J6 (N27)

N40 J11 D'KETT (I don't see the need for N40 J11, just spell Dunkettle fully)

N25 J2 (Same here, just say Little Island)

Bishopstown (before J3):

AIRPORT

R'SKIDDY (N28)

M8 J18

Bandon Road (N71 before J3)

N40 J6 (N27)

N40 J9 (N28)

N40 J11 (I would just say Dunkettle if it can fit)

Sarsfield Road, Wilton (before N40)

N40 J1 (N22)

N40 J9 (N28)

N40 J11 (I would just say Dunkettle if it can fit)

Togher (before J5)

AIRPORT

N40 J9 (N28)

N40 J11 D'KETTLE (I would just say Dunkettle if it can fit)

Togher/Leghanamore (before J4)

J3 (N71)

J1 (N22)

N27 South

CITY (I would be more clear with CITY CENTRE)

M8 J18

N40 J1

N27 North

AIRPORT

N40 J9 (N28)

N40 J1 (N22)

Tramore Valley (before J7)

J10 MAHON

R'SKIDDY (N28)

N25 J2 (I would just say Little Island)

Tramore Valley (before J6)

CITY (N27) (I would be more clear with CITY CENTRE)

AIRPORT

N40 J1 (N22)

Bloomfield (before)

M8 J18

N25 J2 (I would just say Little Island if it can fit)

Maryborough (before Bloomfield)

N40 J6 (N27)

N25 J2

M8 J18

Bloomfield (after)

CITY (N8) (I would be more clear with CITY CENTRE)

M8 J18

N25 J2 (I would say Little Island if it can fit)

Lower Glanmire Road (before Dunkettle)

(Showing disruptions at the moment but I think it was M8 J18, N25 J2 and Ringaskiddy)

Little Island

CITY (N8) (I would be more clear with CITY CENTRE)

R'SKIDDY

AIRPORT

Carrigtwohill

CITY (N8)

R'SKIDDY

AIRPORT

KrisW1001

There’s limited space on the signs. People will learn the junction numbers eventually, just like they have for the M50.

As for Dunkettle, "M8,N25" would be of more use to travellers than "Dunkettle".

DylanQuestion

https://www.boards.ie/discussion/comment/119457285#Comment_119457285

That's actually what I mean. Since there is limited space, they should try use the space better. For example, N40 J11 D'KETTLE is 14 letters and 2 spaces wide. Would it not just be better to write Dunkettle? Or as you said, N40 J11 (M8/N25)

arrianalexander

The people traveling on it frequently will know the names

Those infrequently or once off will probably only know the m8,n25 etc

gooseman12

Looks like they have started putting the surface down on the m8s to n25e link, there's a thin strip of black visible in the cam that wasn't there before now anyway.

https://www.dunkettletraffic.ie/live/?id=2

AugustusMinimus

https://www.boards.ie/discussion/comment/119459434#Comment_119459434

Passed it earlier. The tie in works for Link E with the N25 is at a very advanced stage. Suspect we’ll get a solid update in the email tomorrow.

Chris_5339762

It does seem E is very advanced... though I still can't see how E can open without the Ibis Slip being closed. And that can't realistically be closed until the GSJ is done, so traffic that would have used the Ibis Slip can get onto the N25 and N40. I'd love to be wrong though.

cantalach

https://www.boards.ie/discussion/comment/119461108#Comment_119461108

GSJ = ???

Mother Trucker

https://www.boards.ie/discussion/comment/119462857#Comment_119462857

Grade Separated Junction.

hans aus dtschl

Sorry to be harping on about it still but the Dublin-Midleton V Mahon-Little Island weaving here still looks tight to me: will be very interesting.

Dunkettle Interchange Upgrade - Weekly Newsletter 12/08/2022 - YouTube

Mushy

https://www.boards.ie/discussion/comment/119476239#Comment_119476239

When coming from the tunnel to head to Little Island, will that be two lanes wide? I can't get a scale of how wide lanes look in the videos

AugustusMinimus

https://www.boards.ie/discussion/comment/119478694#Comment_119478694

2 lanes by the look of the drawings on the website.

https://www.dunkettle.ie/media/1339/traffic-movements_from-n40.jpg

Mushy

https://www.boards.ie/discussion/comment/119479049#Comment_119479049

Yeah people will definitely be in the right hand lane and trying to get across two lanes in a short enough space of time. Assume it'll be sign posted for people not to do that, but will still happen.

KrisW1001

I think we’ll have to wait for the opening for everyone here to to be fully convinced, but this is really not going to be a problem. A similar arrangement works pretty well on N40 Westbound between Kinsale Road and Togher (westbound) and between Togher and Sarsfield Rd.

I've drawn out the lanes, roughly to scale, but straightened so you can see the relative lengths. The whole diagram left to right is just over a kilometre long. The trick is that the traffic from the tunnel will be sorted into "for Little Island" and "N25" long before the M8 traffic joins.

It's not on the drawings, but I suspect that there will be some sort of soft physical divider installed between the rightmost lane out of the tunnel and the left for at least some of the length between M8 traffic joining and Little Island traffic leaving - that's the dotted green line on my diagram.

hans aus dtschl

Yep lovely diagram. Really helps to understand the flows.

But I think I now finally understand why we don't agree on this!

Your "From City" should also be West of the "Little Island West" I think? Will the City traffic be physically prevented from using the Little Island West slip? I don't think so. You'll have all three flows merging together BEFORE that slip I thought?

If it's only Tunnel and M8 that can use the Little Island West slip then I agree there's probably no problem. Because the "Eastbound" lane from the Little Island West junction would only really begin at that point.

Chris_5339762

I don't think so, City - Little Island will use the new sliproad just after the Dunkettle roundabout - so they won't have to interact here.

hans aus dtschl

Yep, in that case the green markings in KrisW's graphic might be exactly right: preventing any more than one merge/weave here should mean it's fine!

Edit: I hadn't really considered that people would go TO Little Island via what I would have called the "Ibis Slip". Traditionally I would have used that to go to Glounthaune or Glanmire but never Little Island. I seem to have retained that mental block/blind-spot!

And they had even drawn this clearly in the drawings (attached)

N8 to Little Island.PNG

Interestingly most of that whole route will be a "low noise surface" too apparently.

AugustusMinimus

City to Little Island will use the Glounthaune slip which starts to the west of the current roundabout. I agree with Kris. Should be no weaving issues.

See the bottom right diagram in the link.

https://www.dunkettle.ie/media/1337/traffic-movements_from-n8.jpg

hans aus dtschl

https://www.boards.ie/discussion/comment/119480640#Comment_119480640

Exactly. that's the one I hadn't wrapped my head around at all. Because it's ONLY M8 and Tunnel merging on that stretch, I do think it'll be fine too.

All along, I had it in my head that the City traffic was coming through there too, and I just couldn't see how it would work!

Mushy

https://www.boards.ie/discussion/comment/119479695#Comment_119479695

Will there not be a possibility to go from M8S to N25E? It looks that way in the drawings, so if cars are merging across those 2 lanes, then I've no trust in people to get into the lane coming from the tunnel to go to Little Island west early enough. Some form of divide along that slip would be handy, at least people would be aware fairly quickly.

Or is it a case that the 2 lanes coming from the tunnel can actually go on n25e? I thought one lane would go up the slip and effectively end, with the right hand lane going to n25e

AugustusMinimus

A lot of surfacing work going on, on Links A and E tonight.

Chris_5339762

https://www.boards.ie/discussion/comment/119481957#Comment_119481957

Nah, both lanes from the tunnel will end up going to N25E. Every other movement coming out of the tunnel is a slip of some sort.

In reality I feel the right hand lane will still be faster as there may be less merging effects along the section in question.

KrisW1001

https://www.boards.ie/discussion/comment/119481957#Comment_119481957

M8 South to N25 E is possible, but it is only a single lane - is that where the confusion is? Where this meets the two lanes that originated from the tunnel, there will briefly be three lanes together. Traffic from M8 South that wishes to go to N25 will simply move one lane right, and that's it.

Traffic on either lane from the tunnel can go to N25 E, simply by staying in lane The left lane of these two can also go to Little Island West by moving left one lane. I imagine measures will be put in place to prevent the right-hand lane being able to dive straight across to the Little Island exit, but that may not be necessary at all.

This exact same design has already been used in Cork at the N40 Kinsale Road Roundabout, to allow traffic from the roundabout to mix with N27 South traffic and then split out again to Togher and N40 Westbound:

https://www.google.com/maps/@51.873356,-8.4724159,3a,44.3y,279.31h,92.26t/data=!3m9!1e1!3m7!1sQ_tgdh9qdh2OBu-FjXbWnA!2e0!7i16384!8i8192!9m2!1b1!2i30 . Imagine the two rightmost lanes here have come from the tunnel, that the one joining from the left is from M8 and that the Togher exit is the Little Island West exit, and you've got exactly the same arrangement, the only difference is that the distances will be a little longer at Dunkettle.

hans aus dtschl

Yep I'm guessing the tunnel "right hand lane" will be marked "N25 Eastbound", the tunnel "left hand lane" will be marked "Little Island".

That tunnel "left hand lane" will then be asked to move one lane left to get to Little Island. I don't think they'll be formally signed that "staying in lane" will bring them East. (Remember, staying in lane will also allow them to go to Little Island East, soon after, so it's not a big problem).

The Dublin M8 traffic will be asked to move one lane right to get to the N25 East.

It's just two movements in one place: it's short, but should be fine. At 60kmh maybe it's 30 seconds overall to complete your move, which will be well signed beforehand. I think it should be OK.

pajoguy

The section south of the lake/attenuation pond is going to be tricky when you will have traffic following the blue and red arrows. There will be traffic moving left from the tunnel to go to little island and traffic moving right from the M8S to N25E. It is very hard not to see incidents occurring here.