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

kub · 06-09-2015 10:58pm

I noticed a new warning sign has been installed to the middle of the N40 Eastbound approx 100 meters before the Rochestown/ Carrigaline/ Ringaskiddy exit. Its one of those traffic queuing warning signs, a sign we will be waiting longer for this Dunkettle project.

Leonard Hofstadter · 29-09-2015 10:52pm

This is now officially going ahead, very long overdue:

http://www.dttas.ie/press-releases/2015/minister-donohoe-confirms-%E2%82%AC10bn-investment-our-transport-future

jank · 30-09-2015 9:27am

So what is the time line now?

AugustusMinimus · 30-09-2015 9:45am

This and the N28 scheme will completely overwhelm the N40 at the Douglas flyover. Will certainly require an expensive widening to 3 lanes in each direction.

People who disagree, bookmark this post for future criticism.

marno21 · 30-09-2015 12:16pm

AugustusMinimus wrote: »

This and the N28 scheme will completely overwhelm the N40 at the Douglas flyover. Will certainly require an expensive widening to 3 lanes in each direction.

People who disagree, bookmark this post for future criticism.

This. The decision to build the South Ring so cheaply is slowly coming back to haunt as 1. There is so many elements of the road that needed upgrading, and 2. Every time some element is upgraded another gets jammed. After the M28 and Dunkettle are sorted there will be a lot more pressure on both the Douglas flyover and the JLT, meaning that the North Ring will surely be back on the agenda.

AugustusMinimus · 30-09-2015 12:29pm

marno21 wrote: »

This. The decision to build the South Ring so cheaply is slowly coming back to haunt as 1. There is so many elements of the road that needed upgrading, and 2. Every time some element is upgraded another gets jammed. After the M28 and Dunkettle are sorted there will be a lot more pressure on both the Douglas flyover and the JLT, meaning that the North Ring will surely be back on the agenda.

I think the tunnel itself will be sufficient for quite some time. The problem at the Douglas flyover is merging issues.

At a guess, the Douglas flyover is the most heavily trafficked piece of road in the state outside of Dublin. It takes more traffic than anywhere else in the N40 yet it is still only 2 lanes where a lot of the rest of it is 3 lanes.

Once those 2 new schemes open, the pressure on the Douglas flyover will be intolerable. Expect short term solutions at rush hour such as ramp metering etc.

IMO, when the M20 eventually comes back on the schedule, you'll see NRR East being bundled with it. NRR West won't be built for years as it requires a lot of tunnels / viaducts.

grogi · 30-09-2015 4:22pm

marno21 wrote: »

This. The decision to build the South Ring so cheaply is slowly coming back to haunt as 1. There is so many elements of the road that needed upgrading, and 2. Every time some element is upgraded another gets jammed. After the M28 and Dunkettle are sorted there will be a lot more pressure on both the Douglas flyover and the JLT, meaning that the North Ring will surely be back on the agenda.

But this will always (within reason of course - 15 lane highway would probably be able to host all cars in the county) be the case.

Once you upgrade one piece of infrastructure, a bottleneck in another one reveals. And the more capacity the road network has, the more keen to travel by car people become, almost immediately consuming that capacity...

hans aus dtschl · 30-09-2015 4:53pm

grogi wrote: »

But this will always (within reason of course - 15 lane highway would probably be able to host all cars in the county) be the case.

Once you upgrade one piece of infrastructure, a bottleneck in another one reveals. And the more capacity the road network has, the more keen to travel by car people become, almost immediately consuming that capacity...

With due respect, grogi, these bottlenecks aren't being "revealed" per se, they're known about know and were predicted in the 90's, but the decision was made not to spend upfront, as such a large infrastructural spend was seen as hard to justify.

Similar to the metro north, they kind of fudged it, because the politics was unpalatable.

AugustusMinimus, what do you mean by Douglas flyover and NRR East/West? I presume Douglas flyover is the section passing the village itself (across from the shopping centre) and I presume by NRR East/West you mean from East and from West?

AugustusMinimus · 30-09-2015 5:08pm

hans aus dtschl wrote: »

With due respect, grogi, these bottlenecks aren't being "revealed" per se, they're known about know and were predicted in the 90's, but the decision was made not to spend upfront, as such a large infrastructural spend was seen as hard to justify.

Similar to the metro north, they kind of fudged it, because the politics was unpalatable.

AugustusMinimus, what do you mean by Douglas flyover and NRR East/West? I presume Douglas flyover is the section passing the village itself (across from the shopping centre) and I presume by NRR East/West you mean from East and from West?

Douglas flyover is the part between the Douglas west exit and the Bloomfield interchange. Both carriageway are well over capacity at peak times with traffic backing up in both directions. Going west, the Dunkettle and N28 schemes will make things intolerable.

The completion of the Sarsfield and Bandon flyovers revealed the lack of capacity travelling eastbound with traffic backing up from the Douglas flyover badly at peak times.

The weird thing is that queues travelling east to Dunkettle have reduced since the flyovers have opened as the queues have transferred back to Douglas.

NRR is the North Ring Road schemes which are divided into 2 schemes.

West: N22 to N20
East: N20 to N8

East will be built first with west being the last bit to be built. Expect easy to be bundled with M20 south (Blarney to Mallow)

marno21 · 30-09-2015 5:11pm

Has there been any route rumoured for the M40 North Ring N22 to M20 section yet? Would like to see these tunnels and viaducts

AugustusMinimus · 30-09-2015 5:17pm

marno21 wrote: »

Has there been any route rumoured for the M40 North Ring N22 to M20 section yet? Would like to see these tunnels and viaducts

There's an N40 NRR thread somewhere. Think I put up some images of a proposed viaduct / bridge over the Lee near Ballincollig.

The road will link in with the current N22 going from the Poulavone viaduct to current J1 on the N40. This section will be upgraded with both roundabouts grade separated.

Finally, junction 1 on the N40 will be upgraded. An additional bridge will be built with the current dumbbell being converted to a signalised grade separated roundabout.

A junction with the M20 will be a free flow partially unfilled cloverleaf. The junction diagram should also be in that thread.

mydiscworld · 01-10-2015 9:26am

At rush hour a lot of people go via Mitchelstown and R513 to Limerick. With Dunkettle upgraded I can see this volume increasing

cork_south · 21-10-2015 10:49pm

AugustusMinimus wrote: »

This and the N28 scheme will completely overwhelm the N40 at the Douglas flyover. Will certainly require an expensive widening to 3 lanes in each direction.

People who disagree, bookmark this post for future criticism.

The Douglas flyover is ready overwhelmed.
It backs up to Mahon slip road every morning heading west.

AugustusMinimus · 22-10-2015 9:00am

cork_south wrote: »

The Douglas flyover is ready overwhelmed.
It backs up to Mahon slip road every morning heading west.

Exactly. Now imagine what will happen when both Dunkettle and the M28 open.

MrDerp · 22-10-2015 11:25am

AugustusMinimus wrote: »

Exactly. Now imagine what will happen when both Dunkettle and the M28 open.

If your predictions come to light, increase flow from Dunkettle would make this section heavy, restricting the benefit of any bloomfield interchange upgrade and creating a merge mess that takes a few km to iron itself out.

I can see Carrigaline -> Bloomfield traffic being tempted to rat-run through Douglas West via the route you've highlighted on the N28 thread, putting them on the auxillary lane for the Kinsale Road roundabout, or merging onto the N40 to continue West. Were you proposing to close the douglas west on-ramp as well as the exit?

This could fill the N40 west up quickly, though n40 east from bloomfield should be improved somewhat by the dunkettle improvement.

I was still living in Dublin when they opened the 3rd lane from Donabate to the Airport on the M1. Within weeks the M50 S shenanigans have moved from J6 (Blanchardstown) onwards, back to J5 (Finglas) and often J4 (Ballymun). Moving the whole time, but it one big concertina.

Removing at-grade junctions has an overall positive benefit on throughput, but upgrading the capacity of intake roads will create a bulky glut of peak traffic. If you're in a concertina, nobody wins.

I think dunkettle will help eastbound traffic, obviously, but it's going to expose capacity issues along the weakest and busiest stretch.

I'm with you. At an absolute minimum, a westbound auxilliary lane from N28 to N27 is required.

AugustusMinimus · 22-10-2015 11:32am

Was only thinking of closing the Douglas West off slip. This would be permissible as there's a Douglas East off slip as well. Would be ructions if Douglas West on slip was closed I'd say.

We're looking at the following I think.

- Dunkettle and then N28 opens
- Douglas flyover beyond breaking point
- Plan put in place for additional lane westbound. This will actually be the more difficult lane to do due to have to build above an existing road. Adding an additional lane eastbound would just require a CPO.
- Once, done the Kinsale Roundabout will find itself clogged worse than ever. Expect remedial works will have to be done there to improve flow. Not sure what they could do there though to improve the situation. Not sure there's enough space to do much.

MrDerp · 22-10-2015 11:41am

AugustusMinimus wrote: »

Was only thinking of closing the Douglas West off slip. This would be permissible as there's a Douglas East off slip as well. Would be ructions if Douglas West on slip was closed I'd say.

We're looking at the following I think.

- Dunkettle and then N28 opens
- Douglas flyover beyond breaking point
- Plan put in place for additional lane westbound. This will actually be the more difficult lane to do due to have to build above an existing road. Adding an additional lane eastbound would just require a CPO.
- Once, done the Kinsale Roundabout will find itself clogged worse than ever. Expect remedial works will have to be done there to improve flow. Not sure what they could do there though to improve the situation. Not sure there's enough space to do much.

Horror show. The cross merging will be a mess overall, from N28 to N27.

Carrigaline - Ballygarvan - Fivemilebridge - Ballinhassig relief road anyone?

(Could start with an M28 to Airport spur)

AugustusMinimus · 22-10-2015 11:53am

MrDerp wrote: »

Horror show. The cross merging will be a mess overall, from N28 to N27.

Carrigaline - Ballygarvan - Fivemilebridge - Ballinhassig relief road anyone?

(Could start with an M28 to Airport spur)

I've actually been informed that Cork Co Co do indeed have intentions of a new road from somewhere around Carr's Hill to the airport. Badly needed I'd say.

hans aus dtschl · 22-10-2015 5:09pm

I know there were plans discussed a couple of years ago (2008/2009) of a bridge between the Grange Road and Carrigaline Road.

Is this part of what you're mentioning, AugustusMinimus? Or a separate idea?
http://www.eveningecho.ie/cork-news/new-bridge-help-end-nightmare-traffic-douglas/49837/

AugustusMinimus · 22-10-2015 5:54pm

hans aus dtschl wrote: »

I know there were plans discussed a couple of years ago (2008/2009) of a bridge between the Grange Road and Carrigaline Road.

Is this part of what you're mentioning, AugustusMinimus? Or a separate idea?
http://www.eveningecho.ie/cork-news/new-bridge-help-end-nightmare-traffic-douglas/49837/

Different project. This is a planned outer ring road to go from the top of Carr's Hill (M28) to somewhere near the airport roundabout.

Would take a lot of pressure off the Kinsale Roundabout and airport hill.

marno21 · 22-10-2015 6:54pm

This road from Carrs Hill to the N27/R600 roundabout should be built and westbound traffic should be diverted via M28/new road to take some pressure off the Douglas flyover westbound.

Funny how Cork is developing an outer ring of sorts before Dublin

Leonard Hofstadter · 22-10-2015 11:10pm

I agree with ye lads, a proper link road between the Airport and Carr's Hill/Carrigaline is definitely going to be badly needed once the M28 and Dunkettle Interchange are done. The N40 can be extremely busy as it stands without having M28 traffic being dumped upon it. Also, the flow westbound will be greater once Dunkettle goes free flow during rush hour times, so anything that avoids traffic having to use the N40/N27 during rush hour has got to be welcomed and done as a matter of priority.

cgcsb · 23-10-2015 9:52am

marno21 wrote: »

This road from Carrs Hill to the N27/R600 roundabout should be built and westbound traffic should be diverted via M28/new road to take some pressure off the Douglas flyover westbound.

Funny how Cork is developing an outer ring of sorts before Dublin

horrific public transport and no planned suburbs is the instigator of expensive road projects in Ireland, case and point being the proposed Galway Bypass.

marno21 · 05-11-2015 4:42pm

There was a crash on the Douglas flyover this morning and because there was no hard shoulder to move it to, the flow of traffic stopped and traffic backed up as far as the JLT.

Will this be on the agenda next?

cork_south · 05-11-2015 5:45pm

AugustusMinimus wrote: »

Exactly. Now imagine what will happen when both Dunkettle and the M28 open.

Sorry, what I meant is that I don't think anyone is going to disagree with you.

That section of road is already unsuitable for the current traffic volume at peak times so obviously in the future when you have additional traffic from the Dublin road, the Waterford road and the city all hitting it without being delayed at the tunnel it's only going to get worse.

marno21 · 30-03-2016 2:39am

Any word locally on this project?

I believe it's shovel ready so we may see a tender soon.

annfield1978 · 30-03-2016 8:15am

Consultants haven't been appointed to do anything post planning afaik. Jacobs took the scheme through planning originally?

Is a D&B proposed or Employer designed?

AugustusMinimus · 31-03-2016 12:03am

Anyone have a guess at the build time for this one.

Unlike with Sarsfield and Band in flyover, the ground here is less marshy and prone to subsidence. However, traffic management during the build is going to be an absolute pain I'd imagine.

Wouldn't like to be the engineering devising traffic management layouts.

marno21 · 11-04-2016 2:58pm

Tender has gone out today for technical advisors for this scheme:

https://irl.eu-supply.com/app/rfq/publicpurchase_frameset.asp?PID=98022&B=ETENDERS_SIMPLE&PS=1&PP=ctm/Supplier/publictenders

This RFT is for Technical Advisory Services to provide all technical advice and any other services as required. This will include for support to the contracting authority during the procurement, design and construction stages of the Scheme. The scheme comprises construction of a new free flow interchange on the site of the existing interchange comprising new road links between the N8, N25 and N40, 43 structures, several culverts and pedestrian and cycle facilities. The scheme also includes the provision of a grade separated junction arrangement to the east of the existing Dunkettle Interchange providing road links to the local road network. The construction activities will include demolition (including over the railway), piling operations, ground improvement earthworks, drainage, earthworks, reinforced earth construction, concrete construction, bridge erection (including over the railway), road construction, road surfacing, service diversions, installation of road signs including gantry signs, installation of noise barriers, installation of traffic signals, provision of road markings, public lighting, landscaping, fencing and accomodation works. Adjustment to the northern portal of the Jack Lynch Tunnel will also be required. The services to be provided include but are not limited to the following: Technical (Tender) Document Preparation, Cost Estimation, Procurement and Tender Management, Undertaking Technical Reviews, Contract Monitoring and Administration services during the design and construction stages of the Design and Build Contract using the NEC3 Option C form of contract.

The deadline for responses is the 18th of May.

annfield1978 · 11-04-2016 11:36pm

Was Dunkettle part of the Infrastructure Investment mentioned last year by Government?

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

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