Monitoring structural integrity of bridges with cosmic rays

When muons strike objects on Earth, they are deflected very slightly from their course. The amount of deflection depends on the chemical composition of the object they hit, with heavier elements causing greater deflection.

Measuring the deflection patterns over time, paired with computer analysis, allows researchers to build up images of structures that are impossible to produce using other non-destructive techniques like X-rays.

Dr David Mahon of the University of Glasgow’s School of Physics & Astronomy has received £459,000 in funding from UKRI’s Science and Technology Facilities Council to support the project, which aims to reduce the cost and environmental impact of repairs to road and rail bridges by enabling earlier detection of structural problems.

Dr Mahon’s work on muography has already been tested in nuclear decommissioning. University of Glasgow spin-out Lynkeos Technology has used the technology to help the nuclear industry map the locations of pieces of radioactive waste stored in concrete-filled containers at some of the UK’s nuclear power plants.

Over the next two years, Dr Mahon will work on reducing the size and improving the scanning speed of the muon detector technology to make it more suitable for use in real-world conditions. In partnership with Transport Scotland, the detectors will be tested at a series of bridges across the city of Glasgow.

Dr Mahon said: “There are more than 74,000 road and rail bridges across the UK, most of which are made from reinforced concrete, and many of which were built between 50 and 60 years ago. That means they’re now getting close to the end of their intended lifespan, so it’s important that they are properly monitored to ensure that they can be repaired when necessary.

“Current inspection methods often require exposing steel substructure, which can lead to rust and further weakening when exposed to rain, so non-destructive testing methods that allow maintenance crews to see inside [are necessary].

“Muography is a technique that’s already proven its worth in the nuclear industry, and it seems ideally placed to enable non-destructive testing in transport infrastructure too. The [funding] will enable us to build on our previous achievements and build new, more portable test kits that can identify fatigue or defects at a much earlier stage than is currently possible. Being aware of problems earlier, before they cause significant damage or disruption, could help bring the overall cost of repairs down.”

Hazel McDonald, chief bridge engineer at Transport Scotland, said: “Muography’s ability to look deeper into structures has the potential to transform structural integrity inspection, ensuring ageing public structures are safe and reducing travel disruption.”

Once the project’s initial research phase is complete, Lynkeos will work to bring the updated technology to market.

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