Construction of the M17-M18 Gort/Tuam motorway: An overview
16 October 2018
The bridge with the woods of Coole Park in the background
Ireland’s newest motorway, the M17 M18 from Gort to Tuam, was formally opened to traffic by Minister for Transport Shane Ross in September 2017, two months ahead of schedule. The motorway scheme runs from the end of the M18 at Gort for a distance of 57km northwards providing safe efficient driving conditions between Gort and Tuam.
Reduce journey times between Tuam and Gort by 20 minutes
Motorists travelling the route will avoid well-known bottlenecks such as Clarinbridge, Claregalway and Tuam. The new motorway will provide safe driving conditions and reduce journey times between Tuam and Gort by at least 20 minutes.
The scheme has been developed as a PPP (Public Private Partnership) between Transport Infrastructure Ireland (TII) and DirectRoute Tuam Ltd (PPP). The scheme has highlighted the expertise of the Irish engineering sector in both the design and contracting sectors in delivering a major piece of infrastructure using innovative design approach and efficient construction methodologies.
The 57km route provided several challenges, ranging from areas prone to flooding where karst limestone was present, to areas of extremely soft ground where calcareous silt and peat were both present. All challenges were successfully overcome in a manner that is testament to the project team involved in the delivery of the scheme.
Decade of extensive preparatory work
The success of the scheme can be explained in part to a decade of extensive preparatory work carried out in partnership by TII (Peter Walsh and John McGuinness) and Galway County Council under the direction of Jack Eising, Liam Gavin and Michael Timmins.
Background to the PPP scheme
In Galway National Roads Office, work had been progressing on a number of separate road schemes including the N17 Tuam bypass, the N17 between Galway and Tuam and the N18 from Oranmore to Gort.
All three schemes were brought through route selection, preliminary design, EIS and CPO stage by Galway County Council with oral hearings being held and compulsory purchase orders confirmed for all three schemes by 2009.
It was decided that the best chance of securing funding for these schemes would be to combine the three schemes into one large project which would be of a suitable size to fit the public private partnership model. And thus the N17 N18 Gort Tuam PPP scheme was born.
The contract was signed in April 2014 and the three-year construction programme was successfully completed ahead of schedule, with good teamwork evident throughout. Speaking at the opening ceremony, Declan Carney CEO of DirectRoute Tuam said “this project was a great example of the public and private elements of the project working very well together” – a view that was shared by all present.
Jacobs Engineering, which represented TII on site, headed up by David Feighery and Stuart Nichol, maintained an excellent working relationship with the three delivery partners on the scheme, namely Roadbridge (project manager Paraic McCarthy), Sisk (project manager Noel Curtis) and Lagan (project manager Seamus Sorohan).
More than 900 workers on site at peak of construction period
The scale of the project was enormous and unprecedented for a west of Ireland road scheme, with more than 900 workers on site at the peak of the construction period.
Carney noted that there had been in excess of 3.6 million man hours worked on the site from the beginning of the project. The scheme enjoyed an excellent health and safety record over the construction period, thanks to several safety initiatives introduced by John Crowley of DirectRoute Construction, which promoted a safety first culture on site very successfully.
Advance contracts clear the way for PPP scheme
CEO of Galway County Council (GCC) Kevin Kelly described some of the advance contracts undertaken by GCC:
The 57km length of the scheme had been subject to archaeological testing.
Where sites of interest had been discovered, all of them were fully excavated and resolved under licence from the National Museum of Ireland. The results of this work has been written up and made available to the public in a number of very worthwhile publications under the guidance of two local archaeologists, Martin Jones and Jerry O’Sullivan.
A series of advance ground investigation contracts were arranged to provide as complete a picture as possible of the underground ground profile. This was of absolute vital importance in an area where karst limestone is very common and cavities in the limestone – in some cases carrying underground rivers – have to be mapped accurately.
Trial holes, rotary core drilling and geophysics used to map underground geology
A variety of ground investigation techniques such as trial holes, rotary core drilling and geophysics were used to map the underground geology. This fed into the route selection process and ensured that the route was situated on competent ground in all locations.
There were numerous sites of ecological interest close to the scheme. All of these sites required careful impact assessment and consultation with the National Parks & Wildlife Service in order to agree appropriate mitigation measures.
All of the ecological mitigation measures, such as providing bat roosts or relocating protected plants away from the road, were agreed and signed off before the road construction contract was awarded.
Divert major ESB and Telecom services out of any conflict zone
We also arranged advance contracts to divert major ESB and Telecom services out of any conflict zone with the road scheme and we set up good channels of communication between our road designers and other infrastructure providers such as Bord Gais which was busy installing a key gas main adjacent to the route of the road, so that the potential for conflict was eliminated at an early design stage.
An Bord Pleanála approved the CPOs and the Environmental Impact Statements prepared by GCC, thereby ensuring that the scheme had full planning permission in advance. Tobin Engineers, Galway, whose project team was led by Tom Cannon, assisted the council in reaching this goal.
We were therefore able to present a ‘shovel ready’ scheme to TFI when it was considering schemes nationally for inclusion in its PPP programme of works. GCC would like to acknowledge the support and encouragement of TII at all stages of this project.
Peter Walsh and John McGuinness helped bring the project to tender stage while Kieran Kelly and Obey Mhondera were on site regularly during the construction phase as ‘authorities representative’ on site.
Great credit is also due to staff in the Galway Roads office, in particular Jack Eising, Michael Timmins, Jerry Dunne, Adrian Farragher, Rachel Lowe, Fintan O’Meara, Laura Heneghan, and Eric Van Der Zee, all of whom have contributed to the success of the scheme.
The liaison team of Tony Collins, Padraig Wall and Niall Morrissey have been on site continuously for the past three years and have done an excellent job in dealing with the many issues that arise on a project of this magnitude, which involved 440 landowners and a land purchase of 470 hectares of land.
Brief description of the project
There are six junctions along the scheme:
1.) Kiltiernan connecting to the existing N18.
2.) Rathmorrissy Interchange which is a three tier grade separated junction with free flow mainline rotary carriageway and freeflow slip roads.
3.) Annagh Hill connecting to the N63 Roscommon Road.
4.) Kilmore Junction connecting to the old N17 south of Tuam.
5.) Airgloony connecting to the R332 Ballygaddy Road.
6.) Mountpotter connecting to the existing N17 north of Tuam.
The construction of the Kilmore junction on the M17 was particularly challenging as it involved construction of a major roundabout in an area of soft ground. Roadbridge and its designers came up with an appropriate design solution whereby the top layer of peat was removed and the underlying calcareous silt (marl), in places several metres deep, was consolidated by means of vertical drains and surcharging of the road formation layer.
Rathmorrisy interchange was also challenging in that it involved the construction of three bridges over the existing M6 Dublin-Galway motorway. The delivery partner at Rathmorrissy Sisk arranged for night-time rolling closures of the M6 to facilitate several 80-tonne beam lifts.
Again teamwork and co-operation with M6 O&M company proved the key to a very successful operation completed without incident. Completion of the structures over the M6 was vital for haulage of road making material along the project road, which was a condition built into the PPP contract in order to avoid damage to local roads.
The delivery partner in the south of the scheme, Lagan Construction, faced challenges of a different kind where significant karst features are found in the limestone underlying the scheme. Lagan and Jacobs engaged excellent geotechnical advisers who developed a karst protocol for dealing safely with any such features, where they arose.
Where there is karst, one will find underground water bearing conduits and several flood mitigation measures were built into the scheme to ensure that the construction work did not interfere with existing groundwater flows.
Enhanced regional competitiveness
At the road opening ceremony Cathaoirleach of Galway County Council Eileen Mannion emphasised how completion of the motorway project would enhance the competitiveness of the region.
“We now have efficient access to international airports at Shannon and Knock, thanks to the completion of the M17 and the M18. This helps our international competitiveness when exporting goods overseas.
“We look forward to the completion of the ongoing work by Galway National Roads Office on the Galway City Ring Road and I congratulate all involved in this marvellous project in bringing this major infrastructure boost to the region.”
Changes to national road network in Galway
Following the opening of the M17 M18 Gort to Tuam motorway, the national road network in the region surrounding the scheme has been reviewed by Department of Transport, TII and GCC. It has been agreed to reclassify a number of roads in the region as shown on the reclassification map.
The principal changes are as follows:
1.) N17 south of Tuam will become the N83.
2.) N63 Claregalway – Roscommon Road will become R354 west of new motorway until it joins with new N83 at Loughgeorge (Claregalway).
3.) N18 north of Kilcolgan will become N67.
4.) N18 south of Kilcolgan will become R458.
5.) N66 Gort Loughrea road will become R380.
Ireland’s first ‘green bridge’
Ireland’s first ‘green bridge’ has been constructed over Galway’s new M18 motorway in a bid to conserve an internationally important colony of Lesser Horseshoe Bats.
As part of the agreed environmental impact mitigation measures, a number of wildlife-friendly features have been incorporated into the design of the M17 M18 motorway project. These include mammal underpasses, situated where mammal activity has been detected by ecologists working on behalf on the project.
The objective of the underpasses is to shabitat fragmentation and avoid road kill. Mammal-proof wildlife fencing has also been incorporated in order to guide mammals towards the underpasses and allow them to cross the carriageway safely.
Another interesting aspect of the project from a conservation perspective is the addition of a ‘green bridge’ to the project. The purpose-built bridge, located near Coole Park Nature Reserve, is the first of its kind in Ireland.
All of Ireland’s 12 bat species are protected under the EU Habitats Directive and require ‘strict protection’ as they are listed in Annex IV of the directive. The Lesser Horseshoe Bat has additional legal protection as they are listed in Annex II, which ensures that important areas for this species are designated as special areas of conservation.
Project engineer Tony Collins described how the ‘green overpass’ has been specifically designed as a flight corridor to channel bats across the motorway. “As part of the ecological investigations carried out at route selection stage we radio-tagged several lesser horseshoe bats under licence from NPWS and tracked their commuting routes.
“We noted a distinct pattern of movement from a roosting site in Kiltartan towards the woods of Coole Park where the bats would feed nightly. The movement was principally along hedgerows where the bats would graze on insects.
“The approaches to the bridge and the bridge deck have been planted with hedgerow vegetation to guide bats to and from the bat bridge. The green bridge will also allow the safe passage of other mammals over the motorway and will also cater for agricultural vehicles.”
Kieran Flood, conservation officer for the Irish Wildlife Trust, welcomed the construction of the bridge and the incorporation of wildlife crossings into infrastructure designs in Ireland. “Any measures to reduce the degree of habitat fragmentation caused by motorway construction is a welcome step in the right direction.”
Wildlife crossings have become increasingly popular in mainland Europe and North America over the past few decades as a known measure to mitigate the effects of habitat fragmentation which is recognised as a factor in loss of biodiversity.
Michael Timmins, director of roads and transportation, Galway County Council, expressed thanks to the elected members of Galway County Council for their continuing support for the project and he also thanked the landowners along the scheme for their generosity and co-operation during the construction project.
Tony Collins, project liaison officer, also noted the positive contribution and store of local knowledge which the local community, both landowners and elected members, had brought to the scheme which had been of great assistance to the project team in arriving at this great stage of the project.http://www.engineersjournal.ie/2018/10/16/construction-m17-m18-gorttuam-motorway-overview/http://www.engineersjournal.ie/wp-content/uploads/2018/10/a-aaag2-1024x768.jpghttp://www.engineersjournal.ie/wp-content/uploads/2018/10/a-aaag2-300x300.jpgCivilconstruction,Galway County Council,Jacobs Engineering,Sisk Construction