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

If you want to see how much was dug out, compare it to this screenshot from 2 weeks ago!

I think you've misread what I was saying there. I was making that point that I think it will be removed. Sorry if that wasn't clear in my post.

Just a question re the tunnel to M8 north movement. Do people think that it'll be one or two lanes? The new bridge can take two lanes but the image above only looks like it will be one. I know its just an artist impression. Obviously you will also have the M8 south to tunnel movement and the N25 east to tunnel slip going under the existing eastern bridge so it will probably be a maximum of 4 lanes or could it take 5?

It’s one lane.

Green arrows = West (N25 and Little Island), two lanes.

Red arrows = South (N40), two lanes: one from N8 (Tivoli), and one from M8 South.

Blue arrows = North (M8), two lanes: one from tunnel to M8 North, one from N25 to M8 North.

On the artist drawing it looks like there may be a possibility of adding a second lane for tunnel to M8 if needed, but right now, one should be plenty - once tunnel-originated traffic isn’t fighting with traffic from N25 trying to go north, things will flow a lot more smoothly.

Some interesting photos from today's email and from a screenshot I just took from the webcam.

Huge amount of earth dug away where the old road ran. Will be interesting to see when they remove the old concrete tunnel covering the rail line.

Tunnel exit showing the pillars now fully formed for the N25 East to M8 North slip. Eventually the mainly Tunnel to M8 north movement will run between both sets of pillars where the 2 orange JCBs are.

Above shows the significant earth works as part of Link F. Huge amount of work done already. This will facilitate the N8 West to Tunnel movement.

Finally, a short from the 4/4 Dumbbell being built to the east of Dunkettle. The bridge is now fully formed with its surface being worked on. Huge earth works completed to the south.

Supposed to be Feb 2024

Early 2024 is the official date, but I’d expect the whole interchange to be more or less complete by the end of next year, but under speed restrictions and with some lane restrictions while the final works are completed. The “opening” will most likely be just the a tape-cutting and the removal of the construction speed limits.

I wonder if the 80 km/h limit that applies to the current interchange will be kept once the new interchange is complete, or will it be raised to 100 - right now, I can see arguments for and against it. The tunnel will stay at 80km/h, but N25 is 120km/h to the west of here, as is M8 to the North.

(I say “80 km/h” but the signage was always pretty confusing: traffic approaching Dunkettle from M8 was shown a 60 km/h speed-limit sign at the roundabout, while other approaches were told it was 80 km/h. The real limit is pretty much a moot point given that the lights normally it impossible to transit the roundabout without stopping, but I always thought it was a bit strange...)

N25 flyover - 100kph/120kph

Tunnel to M8 movement - Maybe 80kph

Everything else can only be 60kph in my view.

60 makes sense.

Actually, this set of junctions was notorious for having missing or contradictory speed-limit signs. As well as the different speed limits on Dunkettle itself (60km/h approaching from the north on M8, 80 km/h if approaching from the east on N25), the Glanmire Roundabout (the smaller roundabout immediately west of Dunkettle interchange) is correctly signed as 60km/h if you approach it on the N8 from Cork city, but if you approach from the N25 overpass (last signed as 100km/h at this point), there are no speed-limit signs at all. For a while, there actually was a “60 km/h” sign here, but it obscured the advance direction sign for the roundabout and was removed, but they never relocated it.

Again, the presence of traffic-lights make the actual limit on the junction itself irrelevant, but if you are heading in to Cork city from the N25 overpass, there is a short stretch (between the Glanmire roundabout and start of the 100km/h limit on N8 West) where you could end up exceeding the actual speed limit (60km/h) despite obeying every speed-limit sign that you can see.

I don't follow: are you saying to go from the tunnel roundabout under the new M8 bridge? I don't think that's possible, the gradient is too severe.

The next "big" move after the current ones we know about, I reckon, will be to route traffic going into the tunnel underneath the bridge being constructed, and move some of the roundabout traffic onto the central island which is currently being dug on the south side.

After that, I reckon the new junction will open with temp tie-ins, as that gives additional options for diversions. Also the Ibis Slip Road can't be closed realistically until that opens.

Drove through this morning. I don’t think it’s too severe at all. Gradual fall from roundabout down under the bridge is possible I think. I’ll throw up some drawings for what I’m thinking over the weekend.

I think they'll change the ramp from the roundabout for N25 east from the present location to the following. The ramp will start before the M8 exit and go under the new M8 (See red lines below). This is pretty much the final alignment. However, I think it will temporarily be accessed via the roundabout.

With the current slip closed, it would allow Link F to be completed to allow the final N8 to Tunnel movement. I could be completely wrong on this 😀

The slip down off the N8 from the city onto the roundabout would have to remain open for a few months to facilitate completing Link F.

I think it would be steep but would be only temporary. I've done up a few drawings in this sense. Current roundabout in blue with sliproads. Green shows the new M8. Red shows the new slip road I'm expecting. This will be integrated into the roundabout and facilitate tunnel to N25 east.

Next, sliproad on right will be closed. The new N8 east to Tunnel movement in orange will be finished. The existing sliproad from the N8 to roundabout will be closed. This could be a method to achieve the cut-over before the roundabout is completely removed.

Here's a view of what's going on tonight. A second crane is in place but it's hard to make out exactly what's going on as the live webcam is blurry and doesn't actually show the area you see below.