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

Cork Trucker · 06-09-2018 8:55pm

Truckermal wrote: »

They really need to widen the slip road so two trucks can use it as opposed to one truck straddling it now!

Here here

paddyref · 07-09-2018 1:24pm

What's the plan here?

.
Cork County Council are also advancing a scheme aimed at improving traffic flow in the general Little Island Interchange area. Tenders for the works required will be invited next month and again the intention is to complete these works in advance of the Dunkettle Interchange Main Construction Phase.

hans aus dtschl · 07-09-2018 2:07pm

paddyref wrote: »

What's the plan here?

.
Cork County Council are also advancing a scheme aimed at improving traffic flow in the general Little Island Interchange area. Tenders for the works required will be invited next month and again the intention is to complete these works in advance of the Dunkettle Interchange Main Construction Phase.

Reducing footpaths and putting in extra driving lanes. I wish I was joking.

Both eastbound Little Island entrance slip lanes will be now able to turn right on to the existing motorway bridge. The bridge footpath will be reduced to a sliver on one (West) side. Bridge will be made 4 lanes wide to accommodate more cars.

The exit from the Eastgate estate to the Crompán roundabout will have two lanes which will be continued further back into Eastgate estate, almost as far as the KFC roundabout.

Entering Little Island from Crompán, the left feeder lane towards Little Island church will be extended further back towards the Crompán roundabout.

I believe the plan for users of any sustainable transport modes may be neatly encapsulated as: "PFO".

Drawing set is here:
https://www.corkcoco.ie/sites/default/files/2018-01/T0100-00_255319-00_PL1_Combined.pdf

I consider these to be relatively typical of Cork Co Co, personally.

AugustusMinimus · 07-09-2018 2:09pm

That entire junction is a disaster. There should have been a separate bridge built between the old road and Little Island with no Eastern Parkway Access.

grogi · 07-09-2018 2:15pm

hans aus dtschl wrote: »

Drawing set is here:
https://www.corkcoco.ie/sites/default/files/2018-01/T0100-00_255319-00_PL1_Combined.pdf

I consider these to be relatively typical of Cork Co Co, personally.

And still no sign of spiral rb... ;(

Why it wasn't designed like that?!

hans aus dtschl · 07-09-2018 2:19pm

It's a major employment centre beside the city, outside the city, not integrated with the city in any meaningful way which sees ~95% private car usage.

Even though it has a very high frequency train line very close by, this was never integrated in any meaningful way with the many industrial developments which have seen almost continuous development/expansion, for the past 5-6 years.

hans aus dtschl · 07-09-2018 2:28pm

AugustusMinimus wrote: »

That entire junction is a disaster. There should have been a separate bridge built between the old road and Little Island with no Eastern Parkway Access.

Also another thing could have been to link the train station entrance directly into the Eastgate industrial estate via such a bridge. There's space beside the garage on the old Cork-Youghal road, currently used as a "Park" but hardly anyone actually uses it and it's not well landscaped / maintained.

How they thought they'd get away with continuous expansion of Eastgate and Harbour Point business parks without improving the infrastructure is beyond me. I've heard stories of people turning down job offers due to the chronic congestion.

Their future plan for a Western entrance to Little Island is pretty shambolic too: roundabout after roundabout.

Frostybrew · 07-09-2018 3:54pm

For Little Island, better public transport is required. Either a feeder bus from the train station and/or a full high frequency bus service from the city. A bus service from Glanmire via the train station doing a circuit of Little Island would be a good option; as it caters for the many people who live in Glanmire and work in Little Island, and will also act as a feeder service from the train station. They should also look at extending the 201 service via Glanmire and increasing it's frequency.

Improving road infrastructure without public transport improvements in an urban area is almost always counterproductive, as lack of an alternative to automobile transport causes increased reliance on the car. The extra road space created by the improvements is then quickly filled and you're back to square one.

We have seen this happen many times, most infamously with M25 improvements in the UK and with our own M50. The same will happen with both the interchange and Little Island improvements. Local commuting traffic needs to be facilitated by good public transport, leaving our road infrastructure clear for commercial vehicles and inter urban transport users.

marno21 · 07-09-2018 4:04pm

Business parks like this should have full time shuttle buses between the train station accessing all parts of the business park, and high frequency trains to meet this.

Little Island is a joke for car dependence, and it's one of the most accessible business parks in rail terms in Cork.

Of course, you have the Tullagreen industrial estate a few km to the east with a rail line running beside the business park and no station.

Hopefully some of this will be addressed in the forthcoming Cork Transport Strategy from the NTA.

CHealy · 07-09-2018 4:14pm

I work in Eastgate, somedays (2 or 3 times a week), it can take me 20 minutes to get from the central roundabout to the roundabout by the bridge, its about 300 meters. So of course the most logical thing they could do is build another huge office building for Lily which once done will add another 400 people into the park, the vast majority of which will bring a car. Those two lanes exiting Eastgate already exsist in an unofficial manner. Anyone know why they cant add an exit ramp onto the motorway at the back of the park? It would single handedly solve the issue.

hans aus dtschl · 07-09-2018 5:59pm

CHealy wrote: »

I work in Eastgate, somedays (2 or 3 times a week), it can take me 20 minutes to get from the central roundabout to the roundabout by the bridge, its about 300 meters. So of course the most logical thing they could do is build another huge office building for Lily which once done will add another 400 people into the park, the vast majority of which will bring a car. Those two lanes exiting Eastgate already exsist in an unofficial manner. Anyone know why they cant add an exit ramp onto the motorway at the back of the park? It would single handedly solve the issue.

I see what you're saying, but think such an exit ramp could be too close to the existing one.
The future design being implemented by Cork Co Co simultaneously with the Dunkettle Interchange Upgrade project sees an exit slip road at the west of Little Island. Most who travel into Little Island regularly will know by looking at it that it's inadequate from the start: it merges with the Dublin-Tivoli traffic using a dumbell interchange configuration. The end result will surely be more Little Island traffic jams and increased rat-running via Sallybrook/Glanmire.

I'm actually quite relieved that people see this Little Island interchange upgrade the same way I do. I thought I was the only one who could see the folly of trying to "improve throughput" without simultaneously trying to reduce the very high % of single car occupancy.
The official feedback reports seem to show virtually no interest in any sustainable transport modes from the business park representatives.

hans aus dtschl · 07-09-2018 6:01pm

marno21 wrote: »

Business parks like this should have full time shuttle buses between the train station accessing all parts of the business park, and high frequency trains to meet this.

Little Island is a joke for car dependence, and it's one of the most accessible business parks in rail terms in Cork.

Of course, you have the Tullagreen industrial estate a few km to the east with a rail line running beside the business park and no station.

Hopefully some of this will be addressed in the forthcoming Cork Transport Strategy from the NTA.

In fairness to them, the train runs at a great frequency, especially around rush hour.

Glad to hear about that strategy: somebody badly needs to start taking control of the outrageous roads planning going on around Cork.

AugustusMinimus · 07-09-2018 6:03pm

Little Island could do with a new junction at the East End. Would take a lot of pressure off the others.

As said already, it’s not the only solution and public transport initiatives are required.

Chris_5339762 · 07-09-2018 6:32pm

hans aus dtschl wrote: »

The official feedback reports seem to show virtually no interest in any sustainable transport modes from the business park representatives.

Typical of businesses nowadays, they couldn't give a hoot about how their employees get to work or how long it takes them, as long as they are at their desks from 9 - 5. Let me guess, anyone applying to work from home would be denyed outright.

Kermit.de.frog · 09-09-2018 5:08am

The M50 was design and build contract. They added freeflow links after the initial plan was given the go ahead.

Any chance here they might do the same for the M8S - M25E link?

coL · 09-09-2018 10:42pm

Kermit.de.frog wrote: »

The M50 was design and build contract. They added freeflow links after the initial plan was given the go ahead.

Any chance here they might do the same for the M8S - M25E link?

None of the original M50 sections were built under a design and build contract. It’s possible that some of the subsequent widening and grade separated intersections were, I don’t know for definite but I doubt it.

marno21 · 09-09-2018 10:54pm

Kermit.de.frog wrote: »

The M50 was design and build contract. They added freeflow links after the initial plan was given the go ahead.

Any chance here they might do the same for the M8S - M25E link?

No.

Kermit.de.frog · 10-09-2018 1:18pm

marno21 wrote: »

No.

You're right. That would be much too sensible. Another cackhanded job it is.

marno21 · 10-09-2018 1:21pm

Kermit.de.frog wrote: »

You're right. That would be much too sensible. Another cackhanded job it is.

If it was feasible it would be included. There are a large number of constraints for this scheme and full free flow was always ambitious. What we are getting is quite an achievement

The N8 towards the city will soon be an R road anyway, so it makes sense that the 3 long distance dual carriageways are served as opposed to the city centre link

hans aus dtschl · 10-09-2018 2:08pm

marno21 wrote: »

If it was feasible it would be included. There are a large number of constraints for this scheme and full free flow was always ambitious. What we are getting is quite an achievement

The N8 towards the city will soon be an R road anyway, so it makes sense that the 3 long distance dual carriageways are served as opposed to the city centre link

The current long-term sees:
Migration of port of Cork container depot to Ringaskiddy.
M20 East connection to M8 at Sarsfield's court.
Both of these would reduce traffic to Tivoli a little.

Additionally, a Park & Ride seems to be earmarked East of the new Dunkettle interchange (West of the new Little Island entrance). This junction will then somewhat resemble the Red Cow Junction 9 interchange on the M50, whereby the previously dominant City Centre traffic is deflected.

prunudo · 11-09-2018 12:49pm

grogi wrote: »

And still no sign of spiral rb... ;(

Why it wasn't designed like that?!

Whats the story with those line markings, goes against standard rules of lane discipline.

hans aus dtschl · 11-09-2018 1:45pm

jvan wrote: »

Whats the story with those line markings, goes against standard rules of lane discipline.

I'm not 100% what you mean, but just for clarity, this is grogi's own representation of the drawing, the actual drawing has two concentric circles, rather than the spiral shown here.

prunudo · 11-09-2018 2:27pm

hans aus dtschl wrote: »

I'm not 100% what you mean, but just for clarity, this is grogi's own representation of the drawing, the actual drawing has two concentric circles, rather than the spiral shown here.

The line markings on the roundabout would suggest that its okay to use the left hand approach lane to exit the 3rd exit.
I know its totally off topic and maybe an oversight by the engineers/designers.

Kermit.de.frog · 11-09-2018 3:07pm

Just take out the roundabout, replace with flyovers, 2 extra new lanes each way and change to motorway status.

Simples.

If people want to support me for President i'll turn this place around!

grogi · 11-09-2018 3:22pm

jvan wrote: »

Whats the story with those line markings, goes against standard rules of lane discipline.

You need to look closely at the markings when approaching this RB.

If approaching from the South, the left lane is only for left turns, while right is for going straight and turning right. However the approach from West have them differently - left lane is for left and straight, while right is for turning right only. This is from the submitted planning documents and I guess they need to be like that to maximise throughput.

I guarantee and there will be clashes at the south and north exits with some drivers following "the standard RSA-invented rules", while some will follow the directional arrows at enterance. The suggested lane markings alternations only reflect those signs at the entrance and once you enter from the correct lane, the lane marks would guide you to the exit. In original planning there are circular lanes only.

Cookiemunster · 11-09-2018 4:06pm

grogi wrote: »

You need to look closely at the markings when approaching this RB.

If approaching from the South, the left lane is only for left turns, while right is for going straight and turning right. However the approach from West have them differently - left lane is for left and straight, while right is for turning right only. This is from the submitted planning documents and I guess they need to be like that to maximise throughput.

I guarantee and there will be clashes at the south and north exits with some drivers following "the standard RSA-invented rules", while some will follow the directional arrows at enterance. The suggested lane markings alternations only reflect those signs at the entrance and once you enter from the correct lane, the lane marks would guide you to the exit. In original planning there are circular lanes only.

Actually the RSA tells you to follow the road markings and directional signage when choosing a lane on approach to a roundabout. It's only if there isn't anything explicitly telling you which lane to use, that they then recommend you use the 12 o clock rule.

And BTW all rules of the road are laws that were at some point invented by the predecessors of the RSA.

Geogregor · 11-09-2018 4:21pm

I think someone just wanted to suggest turbo roundabout:

grogi · 11-09-2018 8:29pm

Geogregor wrote: »

I think someone just wanted to suggest turbo roundabout:

Baby steps... Baby steps... :P

L1011 · 12-09-2018 8:21am

Kermit.de.frog wrote: »

Just take out the roundabout, replace with flyovers, 2 extra new lanes each way and change to motorway status.

Simples.

If people want to support me for President i'll turn this place around!

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

You have to be 35 to run for President

spacetweek · 12-09-2018 8:33pm

Kermit.de.frog wrote: »

You're right. That would be much too sensible. Another cackhanded job it is.

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

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.

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

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