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

Yes, I’d certainly be more cooperative in letting people merge into my lane. Aggressive “I’m damned if you’re getting in front of me” winds me up. I’m just making the point that the legal responsibility lies with the merger.

This ^^ All day long this!!

I've called out this shambles a few times on this thread - from design to implementation - and been rounded on by the fans who insist that less is somehow more.

It's nonsense. Another half-assed, badly planned and implemented "Oirish" solution to something that there was no shortage of other/far better examples to draw from.

Could you tell me how the lanes on exiting the tunnel would work to give both M8 north 2 lanes and to also give N25 east (by far the most trafficked movement) 2 lanes? I’ve asked Kermit but he hasn’t replied.

2 lanes for M8 north is impossible if N25 east is given 2 lanes (which it has to be given traffic levels). The limiting factor is the tunnel only bring 2 lanes and there is no way around this.

I'm not an engineer.. that's up to the I'm sure very well-paid consultants, designers and project managers to figure out. I'm sure there were alternatives mapped out or other designs elsewhere that could have been studied.

All I care about as a motorist is that lanes have been removed, diversions (as Kermit pointed out) put in place to achieve the same thing that the roundabout managed previously (M8-city) and this is somehow better??

People have a short memory, it seems... Here's the actual lane layout approaching the interchange from the tunnel: N40 - Google Maps . From left to right, that's:

1. N8 Cork, M8 Dublin
2. N25 East, M8 Dublin
3. N25 East
4. N25 East (not really a whole lane, more like three cars worth of waiting space)

(Also worth noting in that picture are the "60 km/h" signs, for people complaining about a "new" speed limit being imposed on them)

Yes, two lanes on the old road had "N8 Dublin" painted on them, but they were shared with other movements. And what does two halves add up to...? One. One lane. Just like now, except there will be no lane-weaving when you're on the interchange (people who are too special to read signs notwithstanding), so you get through quicker. On the old layout that second M8 lane was effectively useless, as it was used almost exclusively by traffic for N25 - lots of drivers ended up having to change lane back to the first lane while on the roundabout.

The fact is the new junction is far, far faster to traverse than the old roundabout was. For some reason, people seem to expect that because there are no traffic lights, they can just sail through at 60km/h at any time of day or night. You can't - there's still such a thing as traffic peaks, but even at peak times, traffic gets from one side to the other much faster than it did before.

Ok. You’re complaining about M8 north only having one lane but it is physically impossible to have any other solution without widening the tunnel to 3 lanes.

The only other solution was to have both lanes facilitating M8 north. This would mean only lane 1 could have been used for N25 East. This would be a completely suboptimal solution given N25 is the most heavily trafficked movement.

Exactly. 1 free flow lane vs 2 lanes which have to face traffic lights is a much better scenario.

M8 South to Tunnel is now 1 lane and has no traffic at all anymore. That 1 lane is much more efficient than the old 2 lanes signalised.

Or here at 30 secs in, white van speeding along in right lane taking the right fork. Car further along in the left lane running out of road as the left lane is bollarded off and they have to come to a standstill almost. I could be wrong as it's difficult to see the orange signs, but they seem to say it's the right lane is closed.

Just having a lie down, maybe the heat got to it.

Is it common for rubber ducks to go over?

It depends on what you're driving. 30km/h is probably not to slow for a fully laden HGV, but it's definitely to slow for the roadholding capability of a high end car.

A good few HGV's have come to grief on the the slip from the N40 westbound to the N28 southbound where the limit is 100km/h, until you reach the end of the curve when it drops to 60 km/h

As is so often said, posted speed limits are not a target to be achieved, so something like 50 or 60 km/h on the link in question would seem to be not unreasonable. It's up to drivers of vehicles not not suitable to traverse the curve at the posted speed limit to reduce their speed accordingly.

There are an abundance of charges under the Road Traffic Act which can be thrown at any driver failing to safely navigate the curve, irrespective of the set speed limit.

The lanes exiting the tunnel will change with the final alignment. At the moment you have to be in lane 1 to go to Midleton. It will change to be both lanes 1 and 2 in the final layout. This will result in a big change and hopefully improve throughout going north out of the tunnel.

Has that actually been officially stated? Signage would suggest otherwise? Be great if it happens though.....at least for the evening rush eastbound. Coming the other way in the morning (and to a lesser, but still significant, extent, evening) though is a tougher nut to crack - long queues eastward every morning, including queues from Tivoli (acknowledging though that there are more lanes to be opened here). Don't see any way to funnel traffic from the east into both tunnel lanes southbound without carnage!

Would it not have been better to have designed just one long lane for the N40 from immediately after Jct.2 of the N25 westbound. Would that prevent the stop/start merging queues resulting from the current two into one layout.

With such a long slip lane free-flowing into the tunnel at 60 or 80 km/h it's hard to imaging it backing up all the way to jct 2 and clogging the mainline of the N25.

A breakdown, puncture, or accident would then compromise or even block the entire flow (including for tow trucks, emergency vehicles, etc.). And it would mean that at quieter times of day, all vehicles would have to move at the speed of the slowest vehicle on that link. No thanks.

So you don’t think that the road design should maximise the safe overtaking opportunity all because people can’t merge efficiently. Interesting. I have more faith in people’s ability to get the hang of things.