Malahide Viaduct (2009) Co. Dublin, Ireland
The Malahide Viaduct crosses the Broadmeadow Estuary, just north of the suburban town of Malahide, carrying the double track of the Dublin to Belfast railway line and on which Dublin commuter trains also travel.
On Friday, August 21st, 2009, just after 6.30 p.m. - a busy commuting time - two spans of the viaduct collapsed into the water. The alarm had already been raised as the driver of a Dublin to Balbriggan train, which had passed over minutes before, had noticed a partial collapse and immediately reported it. The signals were set to danger and all traffic was halted. There were no fatalities or injuries though the potential for a disaster was noted by all - on that afternoon alone over a thousand passengers had crossed the viaduct. A Dundalk bound train, with hundreds of commuters, had crossed at 6.20 p.m.
An 11 span timber viaduct was first built here in 1843, for the Dublin and Drogheda Railway and a problem with settlement, noticed soon after construction, was solved by depositing huge quantities of stone around the timber support piers, thereby creating a type of weir. Erosion remained a problem, despite continuous efforts to combat it and in 1860 a new bridge opened with masonry piers supporting wrought iron spans. By 1968, 12 spans of prestressed concrete had replaced the much deteriorated, Victorian iron across the 176 metres of the viaduct. The stone weir remained vital to the stability of the overall structure. Following the August disaster, official investigations immediately got underway to determine the cause of the collapse, while simultaneously plans were drawn up for the rebuilding of the viaduct as it is such a vital a rail link.
In August 2010, The Railway Accident Investigation Unit (R.A.I.U.) issued its report.Erosion had eaten away at the weir and a small breach enlarged as water pressure around it increased. Pier number 4 was swept away by the force of water. No trace of it was found during the investigation and reconstruction. The report also noted the importance of continuous maintenance, personnel training and of record keeping. It appeared as time passed and personnel moved on that the functional importance of the weir had been forgotten and it had become accepted that the piers were founded on bedrock.
Pier 4 was repaired and it, and the other piers, were strengthened by steel piles. New precast concrete spans were constructed and the first trains crossed the Malahide Viaduct on Monday, November 16, a bare three months after the disaster.