IRE: M8 J19 upgrade updates

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jackal
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Re: IRE: M8/N25 Dunkettle Interchange Mway order + EIS

Post by jackal »

Berk wrote:I read the linked EIA report, and I have to say it seems like they’ve gone for the most cackhanded option available. Despite full free-flow options on offer.

Why would anyone want to allow free flow u-turns (from Midleton/Cobh), but not a simple movement like M8S-N8W??

I cannot believe no-one wants to travel to the city centre, Glanmire or other suburbs from Cashel or Dublin. The queues will probably be horrendous.

You would almost think there’s a conspiracy to keep cars out of Cork...
The 'freeflow u-turn' myth strikes again!

The full freeflow options were pretty overbuilt for what they'd actually do. The road to the west immediately hits a roundabout, so you're arguably just generating queues if you put three directions of freeflow into it. 'Structure 14' is a bit of a clue that these are not cost effective options.
Dunkettle orange - Copy.PNG
Dunkettle red - Copy.PNG
The selected option actually seems to be a revision of the red option above, with one freeflow movement removed, saving a lot of money on bridges and removing the offside entries and exits. The purist in me would like full freeflow but I can see why they ended up where they did.

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Re: IRE: M8/N25 Dunkettle Interchange Mway order + EIS

Post by nirs »

Looks amazing. Does no-one protest these upgrades in RoI? In Northern Ireland you can hardly propose building a bridge without environmentalists coming out in droves to oppose. And just try upgrading the roads to Derry... then you have a legal war on your hands.
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Re: IRE: M8/N25 Dunkettle Interchange Mway order + EIS

Post by Berk »

Even if the above is true (about capacity), why force westbound traffic to go eastbound to come off?? Why not let the off-slip segue towards the roundabout??

It just looks like a more expensive version of Patcham Interchange (even if the major movements are take care of).
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Re: IRE: M8/N25 Dunkettle Interchange Mway order + EIS

Post by odlum »

nirs wrote:Looks amazing. Does no-one protest these upgrades in RoI? In Northern Ireland you can hardly propose building a bridge without environmentalists coming out in droves to oppose. And just try upgrading the roads to Derry... then you have a legal war on your hands.
They do indeed protest but currently the only major scheme actively held up by objections, as far as I know, is the M28 also in Cork. A decision is due on that scheme any time now.

viewtopic.php?f=1&t=37825&p=963642&hilit=m28#p963642
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Re: IRE: M8/N25 Dunkettle Interchange Mway order + EIS

Post by Berk »

Maybe the Planning Board is a little more sympathetic to motorists?? :wink:
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Re: IRE: M8/N25 Dunkettle Interchange Mway order + EIS

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Berk wrote:Even if the above is true (about capacity), why force westbound traffic to go eastbound to come off?? Why not let the off-slip segue towards the roundabout??
How would it do that without several additional structures?
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Re: IRE: M8/N25 Dunkettle Interchange Mway order + EIS

Post by Berk »

jackal wrote:
Berk wrote:Even if the above is true (about capacity), why force westbound traffic to go eastbound to come off?? Why not let the off-slip segue towards the roundabout??
How would it do that without several additional structures?
Look at it another way - how many structures will it need to go on its 90° turn eastwards?? You’re probably more au fait with this than I am, but there has to be a change of grade (from motorway level, down (or even up) to) where the dumbbell interchange will be.

Why not simply position the exit slip so it meets the roundabout head on from the north??

At Patcham you have the same situation on the A23 heading south. You can’t directly join the A27 West, you have to come off at the interchange, go east a little bit (not as much as here), then take the first exit west.
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Re: IRE: M8/N25 Dunkettle Interchange Mway order + EIS

Post by Johnathan404 »

The difference in public reaction will be mainly because Cork is a rural county where almost everybody uses their car to go about their normal life. Although you'd think Derry would be similar in this regard.

The tide is starting to turn as people ask why the M50 is still heavily congested despite being completely rebuilt. I should think the ambition in urban areas will start to scale back soon. Look at the evolution of College Green, or Cork's St Patrick's Street car ban.
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Re: IRE: M8/N25 Dunkettle Interchange Mway order + EIS

Post by Berk »

I found St Patrick’s Street to be quite striking. Though again, it’s emblematic of that rotten old one-way system.
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Re: IRE: M8/N25 Dunkettle Interchange Mway order + EIS

Post by spacetweek »

Johnathan404 wrote: I should think the ambition in urban areas will start to scale back soon. Look at the evolution of College Green, or Cork's St Patrick's Street car ban.
But nobody is proposing new roads or road widening anywhere in urban areas. Galway's new bypass is far outside the city. Though I should tell you that Cork's car ban has been overturned.
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Re: IRE: M8/N25 Dunkettle Interchange Mway order + EIS

Post by bothar »

Johnathan404 wrote:The difference in public reaction will be mainly because Cork is a rural county where almost everybody uses their car to go about their normal life. Although you'd think Derry would be similar in this regard.

The tide is starting to turn as people ask why the M50 is still heavily congested despite being completely rebuilt. I should think the ambition in urban areas will start to scale back soon. Look at the evolution of College Green, or Cork's St Patrick's Street car ban.
Any street can only be closed if there is some other route provided.
When the M50 was built it should have had a bus service from Day 1, but still does not.
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Re: IRE: M8/N25 Dunkettle Interchange Mway order + EIS

Post by Berk »

But this is it, isn’t it?? And even if you have an all-singing and dancing bus service in a city like Cork, how does it help a tourist like me who arrives from the airport, and wishes to drive himself around touring the area??

Epic fail, but at least it’s not put me off from returning. On the plus side, the improvements to the N8, N25 and N40 are massive, and they do the county a lot of credit.

Perhaps something more basic is needed, such as rephasing the light sequences, so that north-south flows are better.
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Re: IRE: M8/N25 Dunkettle Interchange Mway order + EIS

Post by odlum »

Love to provide some insight but I have never been to Cork. :(

Whatever issues are in the city I think the county is going to have a pretty phenominal mway network with the schemes in planning - northern ring motorway, M20 to Limerick and various other schemes. A lot of potential in the next few years.

N40 southern ring is being redesignated a motorway this year too as far as I know. Don't think they will can redesignate the JL tunnel though. D2 but no hs.
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Re: IRE: M8/N25 Dunkettle Interchange Mway order + EIS

Post by odlum »

Dunkettle.jpg
Hope this works. Clearer view of movements?

Link D is to the tunnel which is D2. M8 is from the north.

The label "to Cork" is misleading, as you can go through the tunnel to Cork as well.
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Re: IRE: M8/N25 Dunkettle Interchange Mway order + EIS

Post by Bryn666 »

Does the M50 have a hard shoulder through the Port Tunnel? There's no reason for the M40 and M8 not to meet head on.
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Re: IRE: M8/N25 Dunkettle Interchange Mway order + EIS

Post by jackal »

Berk wrote:
jackal wrote:
Berk wrote:Even if the above is true (about capacity), why force westbound traffic to go eastbound to come off?? Why not let the off-slip segue towards the roundabout??
How would it do that without several additional structures?
Look at it another way - how many structures will it need to go on its 90° turn eastwards?? You’re probably more au fait with this than I am, but there has to be a change of grade (from motorway level, down (or even up) to) where the dumbbell interchange will be.

Why not simply position the exit slip so it meets the roundabout head on from the north??
It looks like the proposal includes a weaving space on the eastbound slip between the freeflow interchange and the dumbbell. If you moved the dumbbell west, the merge and diverge would be on top of each other, and would have to be signalized.

Additionally local traffic wanting to head east would first have to head west to the new site of the dumbbell. Basically the problem you highlight of traffic having to head in the 'wrong' direction would still be there, just with the directions reversed.

I do have a different suggestion though. Perhaps they could have put in a freeflow 'u-turn' facility using the dumbbell bridge, similar to the one under the M8 at Seaward Street, Glasgow. It wouldn't be a true u-turn, but would rather allow the sb>wb movement to bypass the roundabouts. It would require the order of the exits on the southern roundabout to be rearranged.
At Patcham you have the same situation on the A23 heading south. You can’t directly join the A27 West, you have to come off at the interchange, go east a little bit (not as much as here), then take the first exit west.
At Patcham 2/8 of the major turning movements are freeflow (and one of those using two crappy roundabout filter lanes with weaving between them). Here 7/8 of them are well engineered freeflow. The comparison only emphasizes what a dramatic upgrade this is.
Last edited by jackal on Tue May 08, 2018 10:34, edited 1 time in total.
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Re: IRE: M8/N25 Dunkettle Interchange Mway order + EIS

Post by odlum »

Bryn666 wrote:Does the M50 have a hard shoulder through the Port Tunnel? There's no reason for the M40 and M8 not to meet head on.

It has a bit of hard shoulder - but yes you are right. I guess under that precedent there is no obstacle. :confused: We'll see soon how much they intend to change.
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Re: IRE: M8/N25 Dunkettle Interchange Mway order + EIS

Post by odlum »

Contract has been awarded to Sisk

https://twitter.com/CISireland/status/1 ... 9673169922

Incidentally it's also expected now that the new M40 northern ring and M20 (Cork to Limerick) motorways will be built as part of the same contract. Two large freeflow junctions will have to be built - one for the M20/M40 and the other which will be the next junction north of this one at Dunkettle where the M40 meets the M8.

Be interesting to see the design which is expected early next year.
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Re: IRE: M8/N25 Dunkettle Interchange Mway order + EIS

Post by nirs »

It's a different world. Belfast is almost triple the size of Cork and yet we've been waiting ten years just to get one junction improved. And Cork is building proper motorway rings. A bit of that thinking up here would not go amiss.
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Re: IRE: M8/N25 Dunkettle Interchange Mway order + EIS

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There's been lots of comment in the press such as the Irish Times discussing the investment in the ports and accesses at Ringaskiddy and Rosslare, in order to provide direct access for passengers and freight, both road haulage to France and Spain, and containers to Rotterdam in order to reduce reliance on the "land bridge" route via Holyhead in future.
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