The M7 Naas Bypass involved large-scale construction of road pavements, bridges and earthworks, with new engineering techniques utilised in pre-stressed and post-tensioned concrete for bridges and embankment construction, writes Paul MacDonald
Civil

 

Author: Paul MacDonald MIEI, CEng, executive engineer/training officer, Kildare National Roads Office

The M7 Naas Bypass Motorway opened on 4 October 1983. It was the first motorway road in the state. The scheme consisted of 12km of dual carriageway and five major bridges, including key structures at the Rathangan Road, Maudlins Interchange and the Grand Canal.

The 30th anniversary of the opening of the M7 Naas Bypass was commemorated by a recent lecture in Kildare County Council presented by a local historian along with a design engineer and an artist who were involved with the scheme.

Historian Liam Kenny highlighted the fact that Naas was the historical meeting point of the Norman routes in Leinster and stated that the engineers who designed the M7 Naas Bypass had created a new configuration of physical and mental maps that enabled modern Ireland to emerge from the past. The new M7 Naas Bypass did, however, retain a continuity from the Norman-era routes in terms of bringing people together on the new road.

The first vintage car registered in County Kildare on the M7 Naas Bypass just before the 1983 opening event (photo: Liam Kenny)

A technical presentation on the M7 Naas Bypass was then given by John Lahart, one of the design engineers with Kildare County Council who worked on the scheme. He stated that the M7 Naas Bypass was an “embryonic first step in creating a new motorway road network” for Ireland.

The scheme was needed to address traffic problems in Naas, where the lead concentration in the air from car fumes was greater than the levels in Dublin city centre in 1978. Business owners initially feared the loss of trade due to the bypass. However, this changed to a distinct support for the scheme from those same businesses with the realisation of the negative impact of traffic congestion within Naas, which effectively bisected social activity within the town.

The scale of construction on the M7 Naas Bypass matched the canal construction programme over 200 years before. The bypass involved large-scale construction of road pavements, bridges and earthworks, with new engineering techniques utilised in the areas of pre-stressed and post-tensioned concrete for the bridges and embankment construction with soft materials.

DESIGN CHALLENGES

Construction of the M7 Maudlins Interchange north of Naas

The challenges in terms of geometric road design was the need to account for intersecting routes at Maudlins, north of Naas where the Waterford route met the Cork-Limerick route, and at the Newhall Interchange tie-in southwest of Naas, where access for local traffic had to be provided. The vertical road alignment had to account for the clearance requirements over the Grand Canal at Osberstown, the need to avoid an impact on the high groundwater table and the tie-in points at the existing roads.

The road layout design also facilitated future extension of the bypass in the medium term on the Limerick-Cork route at Newhall and incorporated a grass median area, which would facilitate future widening from two lanes to three lanes in the long term.

The bypass was built by direct labour construction on the drainage and fencing elements with input from over ten contractors on the bridge, earthworks and pavement elements. Kildare County Council road-design staff were responsible for the engineering design and construction management of the bypass. The project team included: John Carrick, county engineer; Dick Burke, senior design engineer, who had previously worked on motorway projects with consultants in the US and UK; Peter Thorne, senior construction engineer; and the late Tom Carroll, the site project manager.

The earthworks element of the bypass entailed excavation and importation of 1.5 million tonnes of material. The significant geotechnical engineering challenge was the excavation and placement of soft material in the road embankments, hence the experience of staff involved with similar embankment construction in the UK was relied upon for the execution of these works on the bypass.

The opening of the M7 Naas Bypass on 4 October 1983 did elicit fears of a ‘death knell’ for business in Naas. However, by 1985, seventeen new businesses had opened in Naas due to the more amenable shopping environment resulting from the removal of long-distance traffic from the town. Since 1983, an estimated 400 million vehicles have utilised the bypass. Maintenance works have been minimal in nature over the last 30 years, which indicates the high level of quality control by engineering staff during the bypass construction.

The social and economic benefits of the bypass have included accident prevention, time savings and environmental protection through air quality improvements in the Naas area.

PERPETUAL MOTION

Perpetual Motion

A distinctive feature on the M7 Naas Bypass is the ‘Perpetual Motion’ art feature at Maudlins, commonly known as the ‘Blackball’. The ‘Perpetual Motion’ feature was designed by artists Rachael Joynt and Remco de Fouw. The spherical structure is a tubular steel sphere, onto which a 50mm layer of concrete was sprayed to create the road-like surface effect once the surface was painted.

Joynt  stated that the arrows and yellow boxes on the art feature created the spherical ‘road surface’, which symbolises both the perpetual motion of the modern world built by engineers since the Industrial Revolution, and also the important role of the M7 Naas Bypass in linking modern Ireland.

From a historical perspective, the M7 Naas Bypass opening in 1983 added to the rich legacy of industrial archaeology and transport heritage in the Naas area, including the adjacent Grand Canal and the old Tullow Railway, which were commissioned in 1783 and 1883 respectively. The historian Liam Kenny stated that this indicated an interesting “geographical and chronological coincidence” relating to the waterway, railway and road transport infrastructure in the Naas area over the last 200 years.

The bypass accelerated the transition from boat and rail transport in the 19th century to widespread automobile use in Ireland during the 20th century. The design and construction of the M7 Naas Bypass by the engineering staff, direct labour staff and the contractors create a new physical landscape on the journey from traditional to modern Ireland. The scheme inspired the next generation of engineers, who are now designing the upgrade to the M7 Naas Bypass to enhance the social development in County Kildare and the region in future years.

Paul MacDonald BSc(Eng) BSc (Politics) MIEI is a highway engineer/training officer with Kildare National Roads Office. He has over 19 years’ experience in highways, water and environmental engineering. He is a member of the Council of Engineers Ireland and is involved in the Engineers Ireland STEPS school liaison programme. MacDonald has a keen interest in topics such as urbanisation in the emerging states, international engineering contracts and project finance

http://www.engineersjournal.ie/wp-content/uploads/2014/07/The-first-traffic-on-the-M7-Naas-Bypass-led-by-An-Garda-Siochana.jpghttp://www.engineersjournal.ie/wp-content/uploads/2014/07/The-first-traffic-on-the-M7-Naas-Bypass-led-by-An-Garda-Siochana-300x300.jpgDavid O'RiordanCivilconstruction,Kildare,roads,transport
  Author: Paul MacDonald MIEI, CEng, executive engineer/training officer, Kildare National Roads Office The M7 Naas Bypass Motorway opened on 4 October 1983. It was the first motorway road in the state. The scheme consisted of 12km of dual carriageway and five major bridges, including key structures at the Rathangan Road, Maudlins...