'An extraordinary engineering achievement': Cork's Dunkettle Interchange opens 

Peak-hour journey times through the notorious Dunkettle Interchange have been slashed by almost 50% it has been claimed

The Dunkettle Interchange Upgrade Scheme was officially opened on Monday by the Tánaiste Micheál Martin. Picture: Michael O’Sullivan/OSM Photography

Peak-hour journey times through the notorious Dunkettle Interchange have been slashed by almost 50% it was claimed on Monday as the last two link roads in the junction’s €215m upgrade were officially opened to traffic.

Ten years in planning and over four years in construction, the upgrade has created a fully free-flow traffic experience through what had become one of Ireland’s most notorious bottlenecks.

Tánaiste Micheál Martin marked the completion of the vast and complex engineering scheme yesterday by praising those involved for delivering it with the minimum of disruption to general daily traffic.

“We have about 50 various projects all in one here — it’s an extraordinary engineering achievement,” he said.

The €215m Dunkettle Interchange. Picture: Michael O’Sullivan/OSM Photography

“I want to pay tribute to the city council, the county council, to Transport Infrastructure Ireland (TII), for the completion of a very challenging but very significant project, with, we have to be fair, minimum disruption to traffic.

“I can recall when it first started everybody was anticipating with some dread the level of disruption that might occur, given the scale of the project.”

He described it as symbolic of the transformation of the country’s transport infrastructure, combining road upgrades with active and public transport routes, and said investment will continue in the delivery of the M28 Cork-to-Ringaskiddy road project — where preparatory work is already underway and where tenders for construction are due to be awarded this year — and on the M20 Cork-to-Limerick project, where route design work is at a very advanced stage.

The Dunkettle Interchange is at the junction of four national roads — the M8 Cork-to-Dublin motorway, the N25 Cork-to-Waterford route, the N40 Cork South Ring Road and the N8 Dunkettle-to-Cork City route, some 5km east of the city centre.

Transport Infrastructure Ireland CEO Peter Walsh, Mayor of the County of Cork Cllr Frank O'Flynn; Tánaiste Micheál Martin, and Lord Mayor of Cork Cllr Kieran McCarthy at the opening. Picture: Michael O’Sullivan/OSM Photography

Planning for the scheme was approved in 2013, and while advance works including archaeological and ground investigations got underway in 2016, TII didn’t award the main construction contract to John Sisk & Son Ltd until October 2020 following a delay over a failure to agree on increase costs associated with the main building work.

But since construction got under way, engineers have delivered 18 new road links totalling 10km in length, seven new bridge structures as well as upgrade works to five pre-existing structures, and upgrades and resurfacing works to the N25 road between Tivoli roundabout and the Little Island interchange.

In addition, 2.9km of new walkways and cycleways have been developed including the provision of a new bridge across the Cork-to-Midleton railway line, the installation of intelligent transport systems throughout the upgraded interchange, and the installation of new culverts and pollution control facilities, landscaping works, directional signage, and safety barriers.

Traffic volumes through the Dunkettle Interchange are at an all-time high, approaching 120,000 vehicles on the busier days of the week.

But despite this, TII said on Monday that journey times through the interchange during peak hours have reduced by almost 50% on average as a result of the upgrade project.

Journey time savings of almost 60% are being achieved on the N40 to N25 route during peak hours, whilst time savings of over 50% are being achieved on routes accessed via the M8 southbound, it said.

'An engineering feat'

Lord Mayor of Cork Kieran McCarthy said the new interchange stands as an important additional piece in the strategic transport infrastructure in metropolitan Cork.

“This year marks 25 years since the Jack Lynch Tunnel opened, which in its day was seen as an engineering feat,” he said.

“The new interchange is also an engineering feat and adds to the adjacent tunnel’s story and narratives.

A section of the new interchange showing some of the new road alignment pictured at the official opening of the Dunkettle Interchange Upgrade Scheme. Picture: Michael O’Sullivan/OSM Photography

“In our time, the removal of critical bottlenecks creates better traffic flows but also greater connectivity between communities on either side of the River Lee’s estuary.”

Mayor of the County of Cork Frank O’Flynn, said the county council will work to build on the active travel infrastructure delivered as part of the interchange project with further enhancements both east and west of the junction.

“The Dunkettle Interchange works also support the council’s ambition of developing sustainable travel modes by facilitating safe pedestrian and cyclist mobility in the context of the ongoing development of the Eastern Metropolitan active travel corridor which it is planned will extend to Midleton in the near future,” he said.

“These initiatives make it a particularly exciting time in terms of quality-of-life improvements for the people of Cork.”

TII chief executive Peter Walsh praised the cooperation between the Government, TII, the two local authorities, John Sisk & Son Ltd, and Jacobs which ensured the project was delivered.

Valerie O'Sullivan, CEO Cork County Council; Tánaiste Micheál Martin; Lord Mayor of Cork, Cllr Kieran McCarthy; Peter Walsh, CEO Transport Infrastructure Ireland; Minister for Enterprise, Trade & Employment, Simon Coveney TD; Minister for Finance, Michael McGrath; Mayor of the County of Cork, Cllr Frank O'Flynn and Ann Doherty, CEO Cork City Council, at the official opening of the Dunkettle Interchange Upgrade Scheme. Picture: Michael O'Sullivan /OSM PHOTO

Sisk Civil Engineering Ireland managing director Will Merriman said it was an extremely complex project, working in and around live traffic at one of the country’s busiest intersections.

The contract for the Dunkettle upgrade includes a three-year maintenance period up to 2027.

In addition to environmental monitoring and landscaping management, it will also include an ongoing focus on monitoring traffic flows through the network.

The numbers behind the Dunkettle:

120,000: Vehicles using the Dunkettle interchange on the busier days of the week;

50%: Average reduction in M8 southbound peak-hour journey times through the interchange since the upgrade;

60%: Average peak-hour journey time savings on the N40 to N25 routes since the upgrade;

10km: Total distance of the new road links;

150,000sq m: Amount of new pavement area;

18: New road links built;

1,000,000m3: Total amount of earthworks moved — enough to fill 400 Olympic-sized swimming pools;

25,000 m3: Total amount of structural concrete poured;

22,500m: Total length of drainage pipes installed;

1,400m: Total length of culverts installed;

180: Construction worker numbers employed at the peak.