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

Actually, I’m wrong about Mahon Point - all of Mahon is inside the 1965-2019 City boundary, so that mess is entirely Cork City Council’s fault. But I’m right about Douglas, which was outside Cork City until the latest boundary change in 2019 finally brought it under the control of the City, along with Glanmire, Ballincollig, Tower and Blarney - Little Island was in the original boundary extension proposal, but that stays with the County.

Was it value for money costing over €200m though ?

As I recall, the sale by the City Council of the landbank in Mahon was what funded the refurbishment of Patrick Street in the early 2000s....

The state didn't have much money and were afraid to spend so much on a project outside Dublin where there was already huge need for capital projects. But I believe that an original design (maybe just a concept?) included usage of the central "escape" bore as a pedestrian/cycle path. A shame that didn't go ahead. But thank god they managed to avoid it being a bridge, as per another concept design!

I think a bridge would have fine as long as it was something like a cable stay with plenty of clearance for shipping. The elevated bridge deck would have facilitate an M8 - N40 flyover instead of the current N8 - N25 flyover we instead got.

The cost for a bridge was huge, because each side was at sea level. This meant it would have needed about a kilometre of ramps on either side in order to reach the required clearance for container shipping - the northern side, as marshland, would have needed deep piling to safely support such a bridge. In the 1980s, when they did the costs, they found that an immersed single-bore tunnel was pretty much the same price as a high-level bridge, and would have negligible impact on shipping during and after its construction.

The single-bore tunnel was upgraded to a twin-bore design when the new National Roads Authority took over budgetary responsibility for the River Lee Tunnel Project in 1992. One of the reasons for the upgrade was that the newly-created European Union was working out the details of a scheme to fund infrastructure projects in peripheral areas, and Ireland was one of the priorities for this funding. That scheme became the EU Cohesion Fund, launched in 1994, and money from this Fund paid 85% of the tunnel’s construction costs.

I've mentioned the Carrigtohill off ramp queueing above. Now, I'm no expert but it seems to me that this is due to a big increase in traffic coming onto the roundabout from the South (i.e. Cobh / N25W side) in recent weeks. IMHO this is people turning off and using the 'back road' to Glanmire / Little Island because of queues further ahead.

I thought you were mentioning the opposite ramp, my apologies. I'm not sure that it's being caused by additional traffic from Cobh side: I'll have a look and see if I can confirm you're right. It certainly is possible.

Maybe I'm wrong, but I go up there every evening and it seems traffic from the N25E is waiting ages for gaps in the traffic coming the 'Cobh side' (i.e. cars coming from Midleton direction, but turning off here to take the old road).

I can confirm this is definitely happening quite a bit.

It's a "ring road" in all its glory!

Completely agree. My view on the Mahon junction is just in isolation.

The N40 is completely above its capacity. Adding additional lanes is not on agenda due to cost and cost / benefit.

Any money would be better spent on

1. Improving public transport
2. North Ring Road
3. South distributor

Rant incoming!!

Was in Cork for the day yesterday and I see the M8 to N40 interchange is still a mess. Honestly it was better when there was a full roundabout.. At least there were 2 full lanes on approach, no last minute braking because of camera vans, and no people cutting/blocking each other off on the merges (more on that in a minute!)

As if those design issues aren't bad enough, some fcking GENIUS decided to block off the right/Dublin lane on approach to the tunnel last night at around 9pm (Thursday night/late night shopping night!) causing a 40 minute tailback to get through the tunnel and then forcing drivers inbound to circle the next roundabout in order to get to where they're actually going!

On top of that (as a side note) was a clown in a 17 year old C reg hatchback straddling both lanes on approach to the tunnel trying to prevent people "skipping" him and merging into the single lane - something I've also seen on Carrs hill at peak times incidentally. WHY can so many people down there not bloody drive?! Don't even get me started on the lack of indicator usage generally!

I don't know what clowns are "managing" this project but they're making a complete mess of it, and of course not a Garda to be seen.

If you don’t think the design is good, suggest an improvement and we can talk about it. It’s worth remembering that you’re still driving through a construction site, though, before making judgments about the performance of the design.

Sorry you had a **** drive, but I suspect you’ll get a lot more sympathy on the Motoring forum than here...

The junction is much, much better now in my experience. I have a friend working in Little Island who also thinks it’s a god send.