Construction organisation Ciria has published a new document to provide guidance on the risk presented to geotechnical assets by scour.
The new C742 Manual on scour at bridges and other hydraulic structures replaces guidance first issued in 2002.
According to Ciria project manager Philip Charles, scour is not a new issue but an update to the existing guidance was necessary because of the increased frequency and intensity of the weather events means that foundations are now being placed at greater risk of scour.
“The experience of the last 10 years has highlighted the vulnerability of the foundations of old structures to scour but there have also been significant advances in knowledge and design tools in the same period,” he said.
Speaking at the launch event today, Rail Standards Safety Board (RSSB) consultant John Dora said: “The UK can expect to experience wetter, warmer and stormier weather in the next 50 to 100 years and we need to design for that change. Recent incidents on the rail network have highlighted that local impacts can have wide consequences so it is essential we have guidance to help develop resilience in our structures.”
Research for the new guidance was led by JBA consulting, Mott MacDonald and HR Wallingford. Funding for the new document was made available by the Bridge Owners Forum; Department for Environment, Food and Rural Affairs; Department for Transport; Environment Agency; Highways England; Institution of Civil Engineers; National Roads Authority; Network Rail; RSSB; the Scottish government; Transport NI; Transport Scotland; and the Welsh government.
“The aim of the project was to create clear, concise, practical and up to date guidance,” said Mott MacDonald hydraulic engineer Andrew Kirby, who led the research team.
The chapters in the document cover different types of scour, different structures that may be at risk of scour, risk assessment and management techniques, scour event preparation and recovery, repair of scour-damaged structures and construction of new structures to mitigate scour.
The industry has welcomed the addition of asset management tools and case studies outlining both successful scour mitigation and examples of failures. Nonetheless, during a question and answer session following today’s launch a number of people highlighted the challenge of designing scour mitigation for weather events that are predicted in the next 30 to 40 years for structures which have design lives that are significantly longer.