N24 - Cahir to Limerick Junction [design and planning underway]

I’m not sure there ever was a “to be 2+2" in that process, except maybe as a line in a spreadsheet. N24 was flagged as a possible candidate for 2+2 by TII back in 2019, but that was before the project started and a proper, in-depth analysis of the requirements was made.

The traffic volumes from M8 to Tipperary Town on this route are really tiny - and not just because it’s a bad road (there’s no other route being used as an alternative it really is just that very few people live there). Using the normal design guidelines, I think we would have ended up with a Type 1 single-carriageway to Tipperary Town, then 2+2 west of there. Making the whole scheme 2+2 would have had such a poor CBA that it would never have been progressed - I believe that the 2+1 pays for itself in CBA terms purely on safety grounds. The fact that it’s not the biggest possible cross-section is not a “Greens” thing; it’s a Department of Finance thing - road projects are among the biggest capital spends in the State, and so they are big targets when money is needed elsewhere (including “elsewhere in the roads programme”).

The 2+1 addresses the safety concerns without inflating the cost of the project and leaving it open to accusations of gold-plating. However, the road remains as a 2+2 west of Tipp town, where there’s at least a chance that future demand will meet that capacity..

On the other, eastern, side of M8, the N24 northern bypass of Cahir is also a 2+1 road - that’s actually a bigger population than on the western side of the motorway, and it's been working just fine. No Greens were involved in that decision - it was built as part of the M8.

The approach to Limerick city will be a very different kind of project, probably a mix of Type 2 ("2+2") and Type 1 ("motorway") DC. Because of the much higher cost per km and the kind of planning challenge that this would bring, It's better to have that as it's own project rather than jeopardise the much needed safety improvement on this part of the road by tying it to an expensive and possibly divisive "motorway" into Limerick.

However, there's no active plan for this N24-N7 link, which is a shame.

Especially given that the profile would allow upgrading to 2+2 relatively easily if it was ever required, I believe?

Why compare M7, the busiest arterial route in the country, to N24, a road connecting the tiny population of villages between Cahir and Limerick?

And Newlands Cross is hardly a good argument: The traffic lights were installed at Newlands Cross in the late 1980s and are from the days where there was almost no money available to do anything. They were an upgrade overall, as they enabled cross-traffic to get a fair share of the junction, but if you were only concerned about getting from Cork to Dublin, they seemed illogical: as ever, most complaints about traffic management measures come from a mistaken idea that the complainer is the only person using the roads.

When money became available, N7 was upgraded piece by piece over a 20-year period - it couldn’t be done in one go, because the road needed to stay open too. Lanes were added, junctions removed, but Newlands Cross was deliberately left until last. This was the busiest interchange on the road, and there was no space for an offline upgrade, so the solution, an online flyover, was always going to make things a lot worse for a while before it got a lot better. If this was done earlier in the programme, then drivers would be hit with those long delays, plus every other existing junction delay, which would have created complete bedlam. Making everything else free-running before doing Newlands Cross meant that during the construction, drivers would only have to deal with the construction-related congestion.

(Incidentally, the reason why M7 stopped at Naas, and N7 Naas Road was left as it was for so long is because the M7 motorway was originally to have taken a completely different route after the Naas Bypass, running to the north of the current N7, and joining M50 at the missing junction 8 before continuing into the city; the Naas Road would then have been de-trunked. That plan was changed in the 1980s, when the idea of building any motorways inside of M50 was ditched)

But, this is N24 between Cahir and Limerick Junction - it’s nothing like N7: there’s no real traffic demand here, and almost no potential for increased demand - it’s a very sparsely populated area, and the traffic counts on the roads here will tell you that. The only reason the upgrade is being done is because the existing road is of such poor quality.

The section from Limerick Junction west is a different kind of road: while this one is primarily a safety upgrade, that one will address capacity too. Bundling both together also pushes the project cost into an area where that high price could result in it being deferred repeatedly, but the safety of of this stretch still needed to be addressed.

It's an argument that either:

a) 100% ignores the finite resources available to complete all the planned projects in a country, or

b) thinks that 'project x' should be reallocated as many of those resources as possible

Yes, you could build this as 2 + 2, you could also build it as a motorway or a high speed maglev.

The road demand calls for 2+1 for safety, the planning for such was done, it was ready to get to the point where it might actually get built, if someone decides to throw their weight behind the whole thing being 2+2 then what they are doing in real terms is delaying the delivery of the project, with a very likely outcome of a reinvestigation of the route being "this should be a 2+1"