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

Wasn't it the most expensive project in the state at that point though? I heard that they agonised over it, and cut the middle tunnel bore to nothing because they were so worried about the cost.

I could be wrong but traffic merging should end up in the left lane of the tunnel and not impact on traffic inbound from the M8 unless they're trying to cut across into that right lane - in which case said flashing and beeping may have been entirely justified as many people do so regardless and (especially in Cork in my experience) without any use of indicators.

Fair enough.. Bad design then caused by a compromised overall solution but compounded by unfamiliarity/inattention/impatience/ignorance.

No unfortunately there's a merge alright, and I've seen similar impatient behaviour from people on the M8 tailgating the cars ahead of them etc, and refusing to allow a merge from the N25. As the previous poster said there might need to be some enforcement here unfortunately.

If we're talking about where the N25>N40 and M8>N40 come together before the northern portal of the tunnel, there is no merging provided for there.

Each lane is separated by a continuous white line the whole way through to the southern portal of the tunnel with 'stay in lane' painted on the road. Any lane changing should only take place after exiting the southern portal of the tunnel where there is over a km for drivers to get sorted before the Mahon exit (Jct 10) is reached.

I'm not blaming anyone in this thread, but the project team (and possibly others) have been woefully inconsistent in referring to that stretch of road. It's the N8, but it all gets wrongly lumped in as N25 sometimes.

As I said I don't have any evidence but was told was that the central bore was (at one point) considered as an actual pedestrian bore. How early this was in design I don't know, and have only been told this by someone working on it, and I haven't got documents from that early in the project. The few documents I have are all as built.

Edit: and I am in agreement that it was built as designed, that wasn't the point of discussion at all, we were saying that the design was whittled down to the minimum because the project was considered so big by the government at the time. People were looking at the original "simple roundabout" design and marvelling at how basic it was.

Edit: doing a bit of googling here and am surprised at the details I'm uncovering. Apparently the largest project by a local authority in the history of the state, and there was heavy pushback against it particularly on costs grounds. It looks like they really agonised over the design, bumping it from a 2-lane tunnel to a 4-lane one.

You appear to take issue with the use of the word bore. I’ll just leave this here; you might find it educational:

Source: https://jacklynchtunnel.ie/general-tunnel-information/

I’m not sure that the central bore was ever planned to be anything other than an emergence escape route. Access and egress would be problematic if it were to be used as a pedestrian route under normal circumstances. The fact that the tunnel got built was a result of an amazing series of coincidences and the efforts of some extraordinary individuals. And it had a very narrow escape….. It was planned as a two lane tunnel (one lane in each direction) and went through the feasibility study and public enquiry as such. In order to drag out making a decision, the then Minister for the Environment (Mayo’s finest, the one and only Pee Flynn) ordered a second public enquiry and the outcome was an increase to four lane tunnel. Doesn’t bear thinking about the consequences had the original plan been pursued.

Your last comment is the same for every Irish city. Huge growth in all Irish cities due to both urbanisation and general population increases.

I would say that the likes of Limerick, Galway and Waterford have experienced even more rapid growth since the 50s than Cork did. Cork has a much larger old core than those cities.

We are a bit off topic, however if it weren’t for the Rive Lee Tunnel there would be no Dunkettle Interchange, certainly not in its current form.

Cork in the mid 80’s was a severely depressed economic wasteland. Fords, Dunlops and Sunbeam all gone, no IT industry and the pharma sector was really just beginning to be more than the original 1969 Pfizer plant in Ringaskiddy. And the rest of the country wasn’t much better. The general consensus was that the country was broke and unlikely to change. The height of our industrual ambition was Willy McCarter’s FOTL in Donegal employing 3,500 making tee shirts and underpants. The Collins and De Valera bridges had just been opened (allegedly the first “non-replacement’ bridges built since the foundation of the State) and despite their small scale were regarded with awe. The state’s motorway network consisted in its entirety of the Naas Bypass, all 5 miles of it.

So when talk started about Cork getting a “downstream crossing” as it was referred to, with a high level bridge or a tunnel at Tivoli being the options, Cork people took little notice, regarding it as kite flying and having little or no chance of proceeding. And anybody outside Cork (i.e. Dublin and Kerry) regarded it as “notions” if they thought about it at all. There was no NRA or TII at the time, so no coordinated approach to planning and prioritising the development of the National Road Network (Shout out to Eamonn for bringing us back to this) so it was up to the local council to try to make things happen. It’s difficult to convey the lack of interest and skepticism that attached to the prospect of the bridge or tunnel. The fact that it did get approved, funded and built is down to a small group of resolute and determined visionaries who took the idea and ran with it, and who by fair means and foul outmanoeuvred the competition (ever other Council and Region in the country and the Department of Finance) and got their project approved. There were also a series of happy coincidences in terms of timing, particularly in the political and financial arenas that allowed the project to “slip through”. So rather than objections, debates etc I think it’s fair to say that the public attitude went from total skepticism about the project in the early days utter disbelief right up to the opening. It happened at a unique point in time, just as an Old Ireland was disappearing forever and the Celtic Tiger was nothing more than lust in it’s father’s loins.

More here: https://en.wikipedia.org/wiki/Jack_Lynch_Tunnel

@Hibernicis The largest factor was the EU Cohesion Fund that allowed Ireland to pay just 15% of the cost of the tunnel. The Lee Tunnel was one of the first schemes funded under this programme.

Thanks for all the info and context. What you're explaining about political wrangling is is the piece that I was reading about last night, it's almost difficult for me to remember how bad things were.

How far we've come!

There is video of proposed two tunnel mentioned above here : https://www.rte.ie/archives/2022/0110/1272861-river-lee-tunnel/

Also some lovely images there of what I presume was LUTS 1978 too thanks!

I'm actually becoming disheartened to see how good LUTS 1978 was: we've had these visionary ideas available for a long time but have ended up with everything that LUTS tried to avoid. We got Dunkettle and the M8 and the N40, that's phenomenal, but it looks like almost everything else has slipped.

The original plan, back in the 80s, was for it to be tolled. I think it was to be 25p or something. This was necessary to fund construction. It became unnecessary when the Germans kindly decided to pay for our roads in the 90s. That of course hasn’t stopped the Echo dragging it up every few years on slow news days and that windbag Terry Shannon seeking voter enrichment from time to time by calling on “the minister to confirm that a toll will not be introduced” when there hasn’t been any mention of it anywhere except in his head.

A City Council Consultation has started about Special Speed Limit changes in the city, and it includes Dunkettle’s speed limits

Looking at the map, it seems:

• Before the tunnel and in it will go to 80km/h
• 60km/h everywhere else except the N25 flyover where it will be 80km/h
• The M8 will go to 100km/h from the N8 slip lane

This only includes City speed limits. It doesn’t include what the speeds will be on the N25 in the County section (the boundary is just west of the dumbbell) but it seems to suggest it will turn to 80km/h there. I’m not sure where it will change to 100km/h and 120km/h

I don't see any reason for the flyover not be 100 kph or for anything less than 80 after leaving the tunnel heading north.

Could the trucks not just voluntarily drive more slowly to suit the conditions?

Interestingly I was told by someone today that I'd rely on for these things that there is acknowledgement within TII on the N25 to N40 connection being undersized for current traffic volumes and that while the captial project is closed the overall project will remain open with some potential on road upgrades to be considered. Would this be a zip merge?

The idea of zip merging has had a lot of air time here already.

However, the fundamental problem of fitting two lanes of traffic from the N25 arriving at 100kmh plus a third lane from Little Island into one lane travelling at 60kmh will always lead to queueing once a certain volume of arriving traffic is reached, no matter how they are integrated into one lane.

The only way to reduce the queueing is either increase the speed of traffic through the single lane bottleneck that connects the N25 to the N40 which might compromise road safety or add a second lane connecting the N25 to the N40 which would require a another tunnel.

I'm a regular user of public transport, both bus and train. Several issues need to be addressed to encourage more people to switch from cars to public transport.

Busses are notoriously unreliable and one can have no confidence in arriving at one's destination at the expected time. In this respect, trains are a far better option.

The issue of loutish behaviour needs to be addressed, there is nothing worse than having one's personal space invaded by others playing loud music or video on their phones or regaling friends, and the rest of the passengers, with an account of the previous night's debaucherous behaviour..