National Highways, in collaboration with AtkinsRéalis, Jacobs, and Estonian start-up GScan, is trialling a breakthrough scanning technology using cosmic particles—muons—for structural health monitoring of ageing bridges across the UK’s strategic road network.
The initiative is part of the Structures Moonshot programme, launched in 2023 to fast-track emerging technologies that can automate inspections and improve the precision of asset condition assessments. With nearly two-thirds of the UK’s strategic road network structures projected to exceed 50 years of age by the end of this decade, National Highways is accelerating its efforts to future-proof infrastructure management.
“The reality we face at National Highways is that we have an ageing network and in particular, ageing structures. Most structures on the National Highways network were built in the ‘50s, ‘60s, ‘70s and ‘80s and by the end of this current decade, almost two thirds of our structures will be more than 50 years old,” said Colin George, Deputy Head of Structures at National Highways and the project sponsor for Structures Moonshot.
George added, “Emerging technology potentially gives us an opportunity to meet that challenge, and that’s why we have embarked on Moonshot.”
Muon imaging, the centerpiece of the collaboration with GScan, enables 3D visualisation of internal structural conditions by tracking naturally occurring cosmic rays as they pass through concrete and steel. The method is particularly valuable in identifying voids and corrosion in post-tensioned bridge structures—critical information that often requires invasive or disruptive inspection techniques today.
“We have now deployed this on a sample structure and have started to get some interesting results,” said Chris Mundell, Technical Director at AtkinsRéalis. “We could actually start to see the tendons within the concrete. It is incredibly exciting for us to start to see the level of detail the technology is giving.”
Phase two of the pilot involved building a test beam embedded with multiple post-tensioning systems and engineered defects to rigorously validate the technology's capabilities. "We want to be able to see individual wires within the strand... and the GScan team is responding," Mundell noted.
From a technical standpoint, GScan’s scanners resemble large boxes filled with 10 miles of fibre-optic strands and custom silicon photomultipliers. These detectors track how muons scatter or are absorbed as they pass through a structure, generating detailed internal maps. “We like to think we have little helpers like Santa Claus has elves. We call them muons – the cosmic particles arrive at the earth from every direction, both night and day. They’re all around us, all the time,” explained GScan project manager Sander Sein.
Sein emphasized the software as equally critical: “The processing involves reconstructing muon tracks, then applying additional layers of object detection, classifying the elements that we can detect, and segmenting it. The long term intention is that this process will help asset owners and engineers make really data-driven decisions about each asset.”
The collaboration model—described as an "enlightened client approach"—has been instrumental in accelerating development and aligning outcomes with real-world use cases. “With Moonshot, we have been able to do things very differently,” said GScan co-founder and chief strategy officer Andi Hektor. “George and Chris and their teams didn’t just check in with us from time to time. They’ve consulted with us all the way through... all from their perspective as the people who would use the technology.”
He added, “That means our development has been really client-led. A lot of technology start-ups are not lucky enough to have that, but for us it has sped up our ability to get results.”
As GScan’s muon imaging proves its mettle in controlled trials, National Highways is evaluating real-world deployment scenarios. If scaled, the technology could redefine how structural inspections are conducted—reducing both cost and disruption while improving safety.
Reference: https://www.newcivilengineer.com/in-depth/national-highways-drives-forward-muon-scanning-for-bridge-inspections-30-04-2025/
