A new 36km road bypassing Strokestown and Tulsk in Co Roscommon is to be built to ensure upgrading of the N5 primary route does not impact on an archaeological complex.

Transport Infrastructure Ireland, which is commissioning the new alignment of the N5, said significant extra sums would be spent to protect a range of medieval, neolithic and megalithic sites , including a “royal site” at an archaeological complex at Rathcroghan, which is bisected by the current N5 route.

However, opponents of the new route have said the indicative alignment to the north of the existing road does not go far enough north, and bisects Strokestown Park demesne, as well as travelling through another archaeological complex northwest of Strokestown and south of Elphin.

The N5 national primary road splits from the N4 at Longford Town and travels through counties Roscommon and Mayo, passing the Castlebar base of Taoiseach Enda Kenny on its way to Westport.

Following the opening of the Ballaghaderreen bypass by Mr Kenny in September 2014, Transport Infrastructure Ireland (formerly the National Roads Authority) identified the section of N5 from the Ballaghaderreen bypass to Scramogue in Co Roscommon as a development priority.

However, the current single carriageway route bisects the Rathcroghan Archaeological complex with its ancillary 240 recorded national monuments and which has been described as the “Tara of the west”. It is the ancient capital of Connacht and the site where the O’Connor kings were crowned.

Because of the archaeological sensitivity of the area the roads authority and Roscommon County Council hired consultants to draw up plans for a new alignment – a 35km single carriageway road from the Frenchpark near the Ballaghaderreen bypass, to Scramogue on the existing N5 near Strokestown.

Complex array

However concern has been expressed that the proposed new road bisects another complex array of archaeological features between Elphin and Strokestown, which includes many more recorded national monuments. The indicative alignment for the new stretch of road also bisects the demesne of Strokestown Park House – home to Ireland’s famine museum.

Dr Mark Clinton chairman of the Monuments and Antiquities Committee of An Taisce said the area was “ a very serious, well preserved landscape”. He was concerned that the new road would ”have cleared the archaeological landscape integral to the royal site”. He said he was surprised an indicative route had emerged in advance of an environmental impact assessment and, given that the road was part of a national road network, he said a strategic environmental assessment should also be carried out.

Ian Lumley heritage officer of An Taisce said a strategic assessment of the road network would show it made more sense to opt for a more northerly alignment with the N5 leaving the N4 not at Longford but at Carrick-on-Shannon. Mr Lumley said efficiency and safety were the driving forces not traffic volume and a more northerly route could combine regional traffic on the N4 to Carrick-on-Shannon, and then on an improved R370 through Frenchpark to the Ballaghaderreen.