DUNMORE BRIDGE, SHANE’S CASTLE ESTATE

Value: £700,000

Client: The Shane’s Castle Estate

The Dunmore Bridge was built by the O'neill family of Shane's Castle in 1801 to carry an estate road over the River Maine. The 100m long Grade B1 listed structure is one of the largest bridges in private ownership in Northern Ireland. The three principal arches spanning the river are dressed with sandstone voussoirs and triangular cutwaters with copings dressed with rhyloite. The main body of the structure is rubble basalt. In 2009 Alastair Coey Architects were appointed as Lead Consultant on this complex structural repair and upgrading scheme. Initial condition surveys were conducted from boats, with specialist input from rope access experts.  The measured survey was carried out using specialist 3D high definition laser scan.

The resulting surveys revealed that overtime the masonry cutwaters and aprons had been eroded leaving the bridge exposed to the full hydraulic force of the river.  Continual water migration through the body of the structure has also resulted in leeching of the mortar, undermining the structural integrity of the arches.  Combined with an accumulation of inappropriate repairs and vegetation growth, major intervention is now required to ensure the long term survival of the important structures. Work has been programmed to commence in 2015.