Work to repair a collapsed section of the Malahide rail viaduct on the Belfast-to-Dublin line in Ireland is under way.
Irish rail company Iarnrod Eireann reports that rocks have been brought on site to rebuild an eroded weir that is believed to have been a significant factor in the collapse.
Work at the Broadmeadow Estuary will include filling a gap that may have undermined the pier, and normalising the flow of water to protect adjacent piers. The work is expected to take three months.
Professor Eamon McKeogh at University College Cork and Dr Eric Farrell of the geotechnical department at Trinity College Dublin are advising the company on the assessment and reconstruction work.
A 20-metre section of the viaduct plunged into the sea last Friday evening just after rush-hour commuter services carrying hundreds of passengers passed over it.
An initial inquiry blamed seabed erosion, caused by recent low tides and heavy rains. Iarnrod Eireann says that the new works will involve straightening piers under the track and installing new beams.