N8/N25/N40 - Dunkettle Interchange [under construction]

Kermit.de.frog · 14-09-2018 6:55am

L1011 wrote: »

There isn't the room for what you're proposing.

Typical Irish parochial nonsense. There is PLENTY of room. They can build over the water as is routinely done in many cities in the US or alternatively CPO the land and make the space.

Stop being such a petal. Let's get it done :cool:

Kermit.de.frog · 14-09-2018 6:57am

spacetweek wrote: »

They are providing the M8S - M25E movement. I think you mean M8S-N8W, which is not being provided and should not be.

Yes it should. I think you mean N25W.

Sam Russell · 14-09-2018 10:07am

Mod: @Kermit.de.frog

Cut the personal comments and insults towards other posters.

Pablo Escobar · 14-09-2018 2:29pm

Kermit.de.frog wrote: »

spacetweek wrote: »

They are providing the M8S - M25E movement. I think you mean M8S-N8W, which is not being provided and should not be.

Yes it should. I think you mean N25W.

There is no N25W from the Dunkettle as far as I'm aware.

AugustusMinimus · 14-09-2018 2:32pm

Pablo Escobar wrote: »

There is no N25W from the Dunkettle as far as I'm aware.

N25 becomes the N8 westbound once it reaches the Dunkettle Interchange.

He’s right that the movement should be free flow though.

hans aus dtschl · 14-09-2018 3:09pm

I think their reason to omit it was because of cost, due to space constraints.

I think it's a fairly poor omission, personally. A lot of traffic already rat runs through Rathcooney and Upper Glanmire to get to the Northside business parks and I expect that similar rat running will happen through Glanmire following the interchange upgrade.

People will say that there isn't much traffic making this movement, but I can tell you anecdotally that a lot of HGV's, buses and people visiting the city from neighbouring counties make this movement. And the new design sees all of this use the same junction as Little Island traffic. It's destined to fail. The only readily-available fix is to change the signage to send all Dublin-Cork traffic around the N40 southbound and we already that will be over capacity at Douglas, so that won't work either.

IMO just another example of critical national infrastructure in Cork being half-done, following in a long tradition after Kinsale Road, Bandon Road, Sarsfield's road interchanges.

AugustusMinimus · 14-09-2018 3:28pm

hans aus dtschl wrote: »

I think their reason to omit it was because of cost, due to space constraints.

I think it's a fairly poor omission, personally. A lot of traffic already rat runs through Rathcooney and Upper Glanmire to get to the Northside business parks and I expect that similar rat running will happen through Glanmire following the interchange upgrade.

People will say that there isn't much traffic making this movement, but I can tell you anecdotally that a lot of HGV's, buses and people visiting the city from neighbouring counties make this movement. And the new design sees all of this use the same junction as Little Island traffic. It's destined to fail. The only readily-available fix is to change the signage to send all Dublin-Cork traffic around the N40 southbound and we already that will be over capacity at Douglas, so that won't work either.

IMO just another example of critical national infrastructure in Cork being half-done, following in a long tradition after Kinsale Road, Bandon Road, Sarsfield's road interchanges.

The design does mean that this movement will have priority at both roundabouts though.

Kermit.de.frog · 14-09-2018 3:49pm

Just because it has priority with two roundabouts does not make it right.

It's so much easier to do these junctions properly the first time and get the most out of the "asset".

Instead as pointed out it's just a continuation of the Father Ted approach to junctions in Ireland.

Our standards are too low in the country and people should not be making excuses for it.

marno21 · 14-09-2018 4:08pm

I have no issue with how the interchange is designed. There are some things to keep in mind here when reality is taken into account. They aren't building the project without that freeflow link as some sort of conspiracy, it's being built like that for good reason.

1. This isn't like the Rathmorrissey interchange where there is large amounts of vacant flat land around the interchange. The interchange is surrounded by steep terrain, a river, a railway line, a business park, Dunkettle House. The approaches on the N40 and M8 are a tunnel and a steep hill, both of which severely constrain the design. There is very limited space here and imo getting 11 of the 12 flows freeflow is enough.

2. This is the most important one. Of the 4 approaches to the interchange, 3 are long distance dual carraigeways to Midleton, Dublin and Ballincollig. The N8 approach slams into a roundabout less than 1km from the interchange. There is no real need to have it freeflow if traffic has to stop there and congestion on the N8 approach into the city will worsen with freeflow from the N40 and the N25, in addition to less impeded flow from the M8.

hans aus dtschl · 14-09-2018 4:24pm

marno21 wrote: »

2. This is the most important one. Of the 4 approaches to the interchange, 3 are long distance dual carraigeways to Midleton, Dublin and Ballincollig. The N8 approach slams into a roundabout less than 1km from the interchange. There is no real need to have it freeflow if traffic has to stop there and congestion on the N8 approach into the city will worsen with freeflow from the N40 and the N25, in addition to less impeded flow from the M8.

Yep that's an astute observation. It remains to be seen how it will work in practice, but I'd have preferred that the Dublin-Cork got its own movement without sharing with the Little Island traffic in any way.
To be specific what I mean is that I'd rather they didn't merge with the N25-Little Island slip ramp (50kmh), didn't go around a dumbell interchange and didn't merge with the Little Island-N25 traffic towards the Dunkettle roundabout.

As it happens, there is some available land northwest of the interchange: they're planning to use this as the pedestrian/cycleway, in another relatively poor design that sees all pedestrian/cycle traffic take a detour around the interchange, rather than the most direct route (essentially ignoring one of the cycle design manual's fundamental principles - "don't detour pedestrians or cyclists"). There is no question that this would have cost more, as they'd need to widen the bridge crossing the Glashaboy river, or add a new bridge south of the existing one, but I expect this may happen in 30-40 years.
As for what to do with the remaining pedestrian/cycle traffic, the ideal route for them would be parallel to the rail line, with a dedicated tunnel under the M8, to join to the new park & ride.

Kermit.de.frog · 14-09-2018 4:33pm

marno21 wrote: »

1. This isn't like the Rathmorrissey interchange where there is large amounts of vacant flat land around the interchange.

Don't think you should use that as an example! Look at the mess they made of it. A "stackabout" instead of a proper freeflow interchange.

It would have been cheaper to build it right. :rolleyes:

If these decisions are not criticised and challenged the same mistakes will keep being made.

There is clearly room for a flyover to cater for the movement in question.

marno21 · 14-09-2018 4:35pm

Kermit.de.frog wrote: »

Don't think you should use that as an example! Look at the mess they made of that. A "stackabout" instead of a proper freeflow interchange.

It would have been cheaper to build it right. :rolleyes:

If these decisions are not criticised and challenged the same mistakes will keep being made.

There is clearly room for a flyover to cater for the movement in question.

What I was saying is that it's valid to complain about Rathmorrissey not being freeflow because the land is easily there for any type of interchange.

The question for the M8->N8 link isn't is the land there, it's how much would it add to the cost and what knock on effects would it have on the rest of the interchange design. The people who designed it obviously decided that the current interchange design was the best to go forward with.

Kermit.de.frog · 14-09-2018 4:41pm

marno21 wrote: »

What I was saying is that it's valid to complain about Rathmorrissey not being freeflow because the land is easily there for any type of interchange.

The question for the M8->N8 link isn't is the land there, it's how much would it add to the cost and what knock on effects would it have on the rest of the interchange design. The people who designed it obviously decided that the current interchange design was the best to go forward with.

What other country in Europe would we be talking about putting a movement like that through two roundabouts on the main route between the two biggest cities?

Can you think of one?

Well, it's not going to change now so no point arguing the toss.

Just don't be surprised when you see the hash they make of the CNR and M20 junctions.

Kermit.de.frog · 15-09-2018 1:19am

A bit crude but 3 potential options

pigtown · 15-09-2018 9:28am

Am I right in thinking that you have to go through those roundabouts to go m40-m8?

BelfastVanMan · 15-09-2018 9:41am

pigtown wrote: »

Am I right in thinking that you have to go through those roundabouts to go m40-m8?

No.

AugustusMinimus · 15-09-2018 12:25pm

Junction Movements

L1011 · 15-09-2018 12:53pm

Kermit.de.frog wrote: »

A bit crude but 3 potential options

Your filename is wrong. They wouldn't do anything in the USA as they haven't invested properly in infrastructure in 30 years. There'd be no junction upgrade to begin with and the n25 flyover wouldn't have been built either.

Those are all basically unbuildable and one would be out of spec due to the fact that you've drawn a rollercoaster track not a road.

AugustusMinimus · 15-09-2018 12:59pm

Here’s a question. What will happen to the old Little Island west junction. Looks like the entrance will remain open but the exit removed?

grogi · 15-09-2018 1:13pm

AugustusMinimus wrote: »

Here’s a question. What will happen to the old Little Island west junction. Looks like the entrance will remain open but the exit removed?

It looks like that.

Cork Trucker · 15-09-2018 3:06pm

From Eoin English of Irish Examiner

https://twitter.com/EoinBearla/status/1040953113014878209

hans aus dtschl · 17-09-2018 9:31am

AugustusMinimus wrote: »

Here’s a question. What will happen to the old Little Island west junction. Looks like the entrance will remain open but the exit removed?

I don't believe the entrance will remain long-term, I think that's a drawing error. I think the Tunnel Maintenance building is the only thing being facilitated by that road, long-term. Can't remember why I'm thinking that, but there would be a bit of conflict with the N8 East to N40 South movement if it stayed.

JupiterKid · 18-09-2018 12:45am

Kermit.de.frog wrote: »

What other country in Europe would we be talking about putting a movement like that through two roundabouts on the main route between the two biggest cities?

Can you think of one?

Well, it's not going to change now so no point arguing the toss.

Just don't be surprised when you see the hash they make of the CNR and M20 junctions.

Come back on this thread, nay - this forum when you have finished school Kermit...

Kermit.de.frog · 18-09-2018 11:18pm

JupiterKid wrote: »

Come back on this thread, nay - this forum when you have finished school Kermit...

Answer the question. I'm looking for ONE other country and we'll do our research to see if they are as incompetent as we are.

P.S No personal insults says one of the mods.

BelfastVanMan · 18-09-2018 11:55pm

Kermit.de.frog wrote: »

JupiterKid wrote: »

Come back on this thread, nay - this forum when you have finished school Kermit...

Answer the question. I'm looking for ONE other country and we'll do our research to see if they are as incompetent as we are.

P.S No personal insults says one of the mods.

Where I live...Northern Ireland.

We tend to look to the rest of our friends in the South with a certain degree of envy; our roads are appalling in comparison. Mostly.

Aontachtoir · 19-09-2018 3:57am

Kermit.de.frog wrote: »

Answer the question. I'm looking for ONE other country and we'll do our research to see if they are as incompetent as we are.
P.S No personal insults says one of the mods.

In fairness, Kermit, you make a lot of statements which could reasonably be viewed as provocative. I'm not certain whether this is intentional or unintentional. However, on these forums it is difficult to tell the difference between people making controversial arguments in good faith and trolls making controversial arguments in bad faith.

I will take you up on your challenge to identify another European country that would have two roundabouts or more on the main road between its two largest cities. My answer is Norway. Oslo is 463 km from Bergen, the second largest city. Oslo is about the same size as Dublin, and Bergen is significantly larger than Cork. Most of the route between the two cities is single-carriageway, with multiple roundabouts and at-grade junctions along the way.

Please clarify whether or not you believe Norway is incompetent.

Cork Trucker · 28-09-2018 6:16pm

Probably the best place for this

https://www.irishexaminer.com/breakingnews/ireland/motorists-warned-of-major-works-on-one-of-cork-citys-busiest-roads-872247.html

Engineers confirmed today that the Silversprings Interchange scheme on the eastern approach to the city centre will get underway on October 1 and should be complete before the end of the year

Separately, improvement works are also proposed at the Little Island interchange.

Kermit.de.frog · 30-09-2018 12:25am

Small issue but I see on the documentation they are going for those hideous bulky gantries (these must be standard now) they put on the M50 (the old British style) instead of going for the slender, more visually appealing modern ones you see around US, Europe and UK.

Sums up Ireland really ala the stackabout at Rathmorrisey. Ape what the Brits were doing 20 years ago 20 years later and remain behind the times.

grogi · 30-09-2018 8:43am

Kermit.de.frog wrote: »

Small issue but I see on the documentation they are going for those hideous bulky gantries (these must be standard now) they put on the M50 (the old British style) instead of going for the slender, more visually appealing modern ones you see around US, Europe and UK.

Sums up Ireland really ala the stackabout at Rathmorrisey. Ape what the Brits were doing 20 years ago 20 years later and remain behind the times.

Do you know what is the wind resistance of each solution and wind predicitons in any of the mentioned region?

Live at Three · 30-09-2018 9:06am

Kermit.de.frog wrote: »

Sums up Ireland really

Hey..stop Ireland-bashing! I'm from there!

N8/N25/N40 - Dunkettle Interchange [under construction]

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