Drones help clone the UK’s Victorian Whalley viaduct for repairs

Network Rail, the owner and manager of most of the UK’s rail networks, has completed a full 3D model of the 176-year old Whalley viaduct, using drone imagery and lasers to come up with a clone that will reveal the places and kinds of repair needed to continue using the structure for passenger and freight transport.

Built between 1846 and 1850, the Victorian era structure is celebrated as an architectural gem, as well as a key link in Lancashire’s Blackburn to Clitheroe railway line. But age, elements, and constant vibrations from trains passing in both directions have undermined the 48-arch Whalley viaduct’s stability, leading Network Rail to undertake the most recent in a series of periodic reviews and repairs. To do so, it used sensor-equipped drones and land-based lasers to create an exact model of the 550-meter span, whose analysis will determine where and how repairs are carried out.

According to National Rail, a total of 300 LiDAR and drone scans were taken of the ornate brickwork of the Whalley viaduct. That modern tech created a complete 3D clone of the 19^th century span with accuracy down to an inch. A thorough study of the computer model will be used to learn where weakening spots are, and what kinds of renovations are needed during the upcoming 18-month repair project.

“We’re always looking to innovate on the railway and seeing drones and lasers being used to care for such an historic structure is really impressive,” said Phil James, Network Rail’s North West route director.  “Using this 21^st century technology gives Whalley viaduct’s engineers a forensic way to plan its essential maintenance for the next 18 months. Great care and attention is going in to make sure our work is right from a heritage perspective. This digital model plays a major role in that.”

UAVs were equipped with imaging sensors to bring back hundreds of high-definition photos of the structure. In times before drones could provide that aerial option to surveying, National Rail had to set up scaffolding allowing maintenance experts to inspect the Whalley viaduct manually. Using the small aircraft and ground-based lasers, however, it could avoid the serious labor of mounting those access structures, but also save time and money needed to complete the job.

“It is fantastic to see this cutting-edge technology being used to preserve such an important and beautiful piece of local history,” said Nigel Evans, deputy speaker of the House of Commons, and a representative of the area playing home to the historical and protected landmark. “I know many people travel long distances to see the iconic Whalley railway viaduct, and it is so important that it is preserved for future generations. It is through projects like this one that its future can be ensured, and I am pleased to see that Network Rail will be undertaking the necessary work to achieve this.”

Based on what the LiDAR model and drone images have already shown, work Network Rail plans on doing to the Whalley viaduct includes vegetation removal and repair of the damage caused by plants and weeds; strengthening the structure; and work to prevent water erosion of its pillars located in and near the River Calder flowing beneath.