THE flight paths of bats living in the Boyne Valley were taken into account in deciding on the height of a proposed new bridge over the River Boyne, the oral hearing into the proposed bypass of Slane in Co Meath heard last week.
The An Bord Pleanala hearing also heard that Slane has the "longest and most severe descent on any national primary route".
The medieval village and bridge are on the main Dublin-to-Derry route and this road, the N2, intersects with the busy Drogheda-to-Navan road in the centre of the village. Some 17,700 vehicles pass through Slane each day, many of them HGVs.
Engineer Seamus Mac Gearailt is a director of Roughan & O'Donovan, which was retained by Meath County Council to select the route and design of the bridge.
The council is seeking permission from the planning board to build a 3.5km dual carriageway at a cost of €46m.
It was decided that a three-span steel/concrete composite 200-metre-long bridge that is 21 metres above the valley floor would be the preferred design.
It will be above the flight paths of the bats and means that lighting will not be needed to prevent them "colliding with the bridge itself or indeed passing traffic."
Mr Mac Gearailt said it was better to increase the bridge height, so that the flight paths are not interrupted.