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

I see they aren’t big up the old roundabout surface north and south of the junction. They however hammered lots of holes into the surface.

Assume they will now just cover the old surface with gravel/clay and the holes are to allow water flow? I find it a very strange approach. Surely it could cause a lot of drainage issues?

25 mph is 40 kph though - not 30 kph - and that sounds like a much more reasonable limit to me.

The loops on US cloverleafs are normally around three times the diameter of this one (typically 1000 ft, versus 100 m).

Measured from the map, the part of the loop here that's under 30 km/h limit has a total length of around 350 metres. That's the maximum, I think it's shorter.

Traversing 350 m at 30 km/h takes 42 seconds. Increase the speed to 50 km/h, and it's 25 seconds.

So, assuming that traffic can take the curve at 50 km/h (and this is just not true; few drivers are comfortable driving at this speed) we're talking about a maximum possible time saving of just seventeen seconds.

"Common sense" says to set the limit to a safe level, and that's 30 km/h. I don't know how you're measuring the speed of cars on the curve, but I'd be very surprised if it's in excess of 30 km/h.

You can argue all you want for a 40 km/h limit, but there is no legal "40 km/h" speed limit in Ireland. The only permitted options are 30, 50, 60, 80, 100 and 120.

I know that loops in the US are normally larger than here. That’s why I said “even on tight turns”. Look at freeway sections in urban areas in CA or NY and you’ll find plenty of loops even tighter than Link F with a 25 mph limit (you’ll find plenty in LA with no posted ramp limit).

Not sure where you’re going with the calculation of the possible time saving. That is missing the point completely. There is an important principle in play here. We are lucky enough to live in a country where the state cannot arbitrarily restrict what we do, as in, it cannot restrict us without reasonable justification. In this instance, the justification would be safety. The international evidence and the personal experience of many who have driven on Link F is that 30 is unjustifiably low. As such, it is an arbitrary restriction.

Regarding the supposed absence of a 40 limit in Ireland, the RTA was amended this year to permit any speed between 20 and 120 (in increments of 10) to be used on variable speed signage. Maybe that is the solution here. 30 in bad weather or when traffic is heavy. 40 otherwise.

There is also the consideration of the N25 E which is below and very close to that loop.

Imagine a vehicle going too fast, going through the barrier and down onto the road below, I imagine that is possibly a concern.

Drove through a few times the last few days and I felt I was watching my speedo more than the road. My cruise control doesn’t work below 50kph either. Not sure the constant speed van presence is optimising safety or throughput on the junction.

How can you be sure? There’s a speed van planted at the end of the 30kph loop since it opened. I’m certainly not taking any risk.

City west ,city north ,city centre would have probably been more logical alright ,

If you didnt know you were on the outskirts of cork city then a few traffic signs are the least of your problems ..

Tbh you're right, if you don't know you're in Cork, a sign isn't going to help. It should read CITY CENTRE (N8), CITY NORTH (R635) and CITY SOUTH (N40). Before approaching the Dunkettle, there are signs saying "Welcome to Cork City", so you should know exactly what city centre is being referred to. Plus, the VMS signs say CITY CENTRE, not CORK. Why Mahon has a sign directing people to Cork makes no sense to me (and it's a bit annoying as I mentioned this with TII years ago and they said the comments would be taken on board). It's like how the N28 signs in Rochestown tell users to access CORK via the N27, when they've been in Cork for nearly 5km. I am really unsure why TII are so afraid of using CITY CENTRE. Here are some examples of TII or the Council replacing CITY CENTRE with CORK

N28 (after Carr's Hill Interchange)

N28 On-Ramp (Rochestown Road)

Bull McCabes

because van inside 60km limit. it very unlikely it getting cars inside 30km limit

Limits are not targets.

The 50 limit as you come up to those roundabouts is for the road network that you're joining - it is not just applied to the roundabout. You have to slow down (and yield to traffic on your right) before entering a roundabout, so your entry speed will not be particularly high. Most traffic on these roundabouts will be travelling at under 30 km/h, especially if it had to stop before entering.

I’ve spent 16 years as a club cyclist in Cork, riding thousands of km per year with a speedo under my nose and a strong sense of self-preservation. So I’m very attuned to how fast motor vehicles move pretty much everywhere in the Cork hinterland. I can say with certainty that (unless traffic or weather intervenes), very, very few vehicles travel at less than 30 kph anywhere. It is a ridiculously low speed in a motor vehicle.

They should have done something with the roundabout to the west and provided the one freeflow link they left out (M8S - N25W). Having cars go through the dumbells to get to Cork really undermines the scheme. It's not a "freeflow" junction. 7/8 movements are freeflow except for arguably the most important one.

Anyone able to comment on this?

Didn't they do piling on one part of the roundabout related to the n25w to m8n structure? Maybe this is similar and they'll end up tearing up the old surface at a later time