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Network Rail responds to inspection failure after narrowly avoiding disaster

Lamington Viaduct

A report released by the Rail Accident Investigation Branch (RAIB) has revealed how close Network Rail came to a major rail disaster after failing to respond to known problems of scour beneath rail bridges over fast flowing rivers. The RAIB's report follows an investigation launched after a passenger train travelling at 110mph was allowed to pass over Lamington Viaduct in South Lanarkshire while the structure was suffering substantial scour damage on 31 December last year.

The RAIB report found that the driver of an earlier train had reported track damage and that a rail inspection team had then reported no significant problem and allowed full speed running. The 05.57 from Crewe to Glasgow was the next service to pass over, revealing track subsidence which led to the line being closed and the bridge inspected fully. The RAIB's report found that the risk of scour at Lamington was identified as far back as 2005. It took 10 years for a scour protection scheme to reach near-readiness for a start on site, but this was deferred to 2016 due to a lack of environmental consent.

The RAIB also found that procedures previously established for monitoring viaducts at risk of scour damage had been abandoned and as a consequence no effective scour risk mitigation was in place for over 100 vulnerable structures across Scotland. Organisational changes within Network Rail had led to the loss of knowledge and 'ownership of structures issues', the RAIB says.

The West Coast Main Line was closed for seven weeks while emergency repairs and construction of scour protection were carried out to the Lamington Viaduct's piers and abutments.

The RAIB's chief inspector of rail accidents, said: "Our recent investigation into the partial failure of the viaduct at Lamington, in South Lanarkshire, serves as a reminder that, under certain circumstances, the scouring effect of a swollen river can undermine bridge piers to the point where the structure above starts to fail. The risk of scour is often higher for older bridges, particularly those with shallow foundations.

"It is of particular concern to me that the vulnerability of this structure to scour had been identified at least 10 years previously. Despite this, insufficient action had been taken to protect the piers from scour, or to monitor the integrity of the viaduct at times of high water flow. The continued operation of trains over this high risk structure, despite a previous report from a driver of a rough ride, provides vivid evidence that the risk of scour was not generally appreciated by those involved."

The RAIB provides three key recommendations relating to the management of scour risk,  response to defect reports and management of control centre procedures, as well as five 'learning points' noted relating to effective management of scour risk.

Network Rail has provided its response to the Lamington incident and the RAIB's investigation:

"We worked closely with RAIB as it completed this report and will carefully review the findings," a Network Rail spokesman said. "The safety of passengers and rail workers is of vital importance to Network Rail and we have already made significant changes to our management and maintenance of scour-risk structures in Scotland since Lamington.

"We have invested over £3m so far this year to reduce scour-risk at four high priority structures and have carried out 277 specialist underwater examinations to assess the foundations of bridges ahead of this winter.

"We have also identified 50 bridge sites where we will roll-out telemetry equipment, to help monitor the impact of flooding on the network and to improve early identification of potential issues."

If you would like to contact Jon Masters about this, or any other story, please email jmasters@infrastructure-intelligence.com.