Scottish Water is using drones to accurately assess the condition of its infrastructure and make key decisions about investment in maintenance or rehabilitation work.

Traditional teams of up to 15 workers can be replaced with just two operatives using drone and Light Detection and Ranging (LiDAR) scanning and measurement techniques.

The bespoke drones fly into sewers effectively replacing workers in challenging and dangerous underground conditions while the more accurate surveys will cut the cost of repairs and maintenance.

Many of the sewers, some dating back to the Victorian era, have previously been difficult to access but much more of the network is now reachable following the collaboration between Scottish Water, its alliance partner Caledonia Water Alliance (CWA), civil engineering trenchless specialist Environmental Techniques and drone manufacturer Good Friday Robotics.

The adapted technology was used together for the first time on a large brick sewer in Bath Street in Glasgow city centre and is set to be rolled out and used at other locations in Glasgow, Edinburgh, Aberdeen and some rural areas.

LiDAR is a laser scanning tool that measures distances and the associated software creates an accurate computerised 3D point field output which can be viewed on-screen. The drone carries the LiDAR and camera onboard as it flies inside the pipe.

A worker controls or pilots the drone as it flies along the pipe and uses video for visual inspection and LiDAR for measurement. The outputs are then manually reviewed by operators to spot and code the defects.

The drones were adapted specifically for sewers and are made of carbon fibre to reduce their weight and extend battery life.

Iain Jones, Risk and Life Cycle Planning Manager at Scottish Water, said: “This is the first time we’ve used drones adapted for sewers and LiDAR together for sewer surveys and we are really excited about it.

“We want to improve the accuracy of our surveys and, for safety reasons, we want to reduce the number of workers needed to carry out survey work inside sewers. The drone does both and they will also help us in our aim to reach net zero carbon emissions by 2040.

“Factors such as depth, flows and debris can significantly slow down a worker entry survey in a way that does not affect the drones.

“Because of the reduction in the number of workers involved, a large number of site vans and vehicle deliveries are not required and so carbon emissions are reduced.”