Ireland's First Inter-Urban Motorway

The new M6 Galway to Ballinasloe PPP scheme is the first inter-city motorway to be completed in Ireland, and, with a project value around €700m, is also the largest ever infrastructure investment west of the Shannon. RPS has worked with the National Roads Authority and local authorities since 1999 to deliver the impressive scheme which has recently been completed and opened six months ahead of schedule.

The 52km motorway links the new Athlone-Ballinasloe M6 section with the east side of Galway city, has 4 km of dual carriageway, five grade-separated junctions, and includes no fewer than 50 bridges –including eight river crossings (one of which is the 120m bridge over the SPA River Suck at Ballinasloe), three rail bridges, and a footbridge. There are two lanes in each direction, and then six lanes in each direction at the toll plaza to maximise time-efficiency. The scheme also incorporates over 30km of side and link roads. Together with the planned Galway City outer bypass this will complete the ambitious new National Primary Route network for the county.

RPS was appointed as consulting engineer –firstly advising on the initial route selection and environmental matters, and preparing the CPO, EIS and preliminary design; then carrying out the design procurement and supervising substantial advance contracts. RPS also implemented environmental monitoring and mitigation measures for the scheme and conducted the detailed design review stage, as well as assisting with technical aspects of the PPP procurement process and working with the National Roads Authority and Galway County Council to monitor the construction stages.

Jerry Grant, RPS Managing Director, says: "The project demonstrates that major infrastructure has been successfully delivered using the integrated project management approach developed by RPS, where engineering, economic and environmental aspects of the project are progressed together by a dedicated, multidisciplinary project team."

A number of advance contracts were carried out ahead of the PPP contract to enable the scheme to be completed in the best achievable time, including advance earthworks to excavate and replace 150,000m³ of peat over a distance of 1.5km for the construction of the embankment foundation, the installation of vertical drainage at some points to enhance progression of foundation works, and site clearance works in accordance with environmental mitigation recommendations.

The progress of environmental surveys was affected by access restrictions during the foot-and-mouth disease outbreaks, but the team worked hard, and was still able to complete survey and mitigation assessments in good time, identifying –and advising on appropriate mitigation measures for- bats, otters, badgers, white-clawed crayfish, Greenland White-Fronted Geese¹ and small white orchid which were all noted in the route corridor.

The route passes through some rocky areas, and it was necessary to quarry rock outside the project boundary to a small extent. To maximise the volume of re-usable materials, rock cuttings were widened and steepened using an inventive cutting process to minimise time taken, which also produced the most attractive rock finish in the cutting. 2.8 million cubic metres of rock was excavated for the motorway, and was all recycled and re-used in the road construction.

The recent completion of the M6 reduces the journey time (to less than 2 hours) and distance between Galway and Dublin, providing a smoother and safer travel option, and significantly reducing through traffic impact on local towns, and overall traffic volume on the R446 (N6).

¹Greenland White-Fronted geese (anser albifrons flavirostris) are regular winter visitors to the SPA River Suck.