So cosmic radiation is a thing and it’s a very real thing that affects the earth and its inhabitants. While the Earth is sheltered by its atmosphere, people on the ground won’t be affected by cosmic rays as much, yet people who travel by plane are exposed to higher amounts of radiation: basically, when you’re 37,000 feet in the air, you’re exposed to more radiation than an atomic plant worker. And now, science has figured out a way to accurately scan large areas harnessing cosmic rays from outer space, just like x-rays in hospitals.
Cosmic ray technology was used to find hidden chambers in the Pyramid of Giza back in 2017, and to search for magma chambers inside active volcanoes and image the Fukushima nuclear reactors. The innovation is now helping National Highways to unlock the secrets of a historic railway tunnel located deep under the streets of Glasgow. Balgray Tunnel, constructed in 1896, stretches for 640 metres under the Kelvinside area of Glasgow and has been closed since 1964.
The upkeep and regular inspections of the structure are essential, and until now techniques such as ground penetrating radar, drilling and visual inspections have been used to check for hidden shafts and highlight potential issues. Now, an innovative process called muon imaging, which harnesses cosmic rays from space to create accurate x-ray-like images, is a way more convenient way to assess the hidden parts of the tunnel.
Muon tomography relies on cosmic rays which are high-energy particles produced by the sun and other cosmic objects that hurtle through space. As they enter the earth’s atmosphere they collide with the oxygen and nitrogen molecules: most of these particles are stopped in the atmosphere but muons particles make it to the ground. Pretty fascinating, right!
National Highways is working with Hampshire-based tech company Geoptic for the trial at Balgray Tunnel that is maintained by National Highways Historical Railways Estate (HRE) on behalf of the Department for Transport.
Prof. Lee Thompson, Geoptic’s Technical Director said:
“Before the survey started, we needed to develop a digital twin of the tunnel using detailed geological data which informs us how many muons we expect to see at any point in the tunnel. Then, inside the tunnel, we use our instruments that detect muons to measure the number of muons at different points.”
“Differences between what we expect to see and what we actually observe can be interpreted as differences in density in the structure of the tunnel compared with that we assumed in our digital twin. As well as identifying hidden voids and shafts our instruments can return valuable information on the shaft position, size and extent.”
During the Victorian era, engineers constructed shafts along the line of the tunnel to speed up the construction process, and to help maintain the tunnel’s alignment on curves. When the tunnel was completed, some of the shafts would be kept for ventilation and others capped at both ends or back-filled. It is safe to say that the importance of being able to locate and examine the hidden closed shafts and any other voids is crucial for the maintenance and safety of the tunnel.
Understandably, the results of the survey are still being assessed to see if future works will be planned.