Why remote surveying of networks?

There are some 800,000km of low-voltage network in Britain. That means keeping tabs on LV assets and their condition is a mammoth job.

“If we didn’t use remote surveying techniques, we would need to drive to each location and walk the network on foot,” explains Ian Draper, senior asset engineer at UK Power Networks.

Not only does the volume make it challenging to survey all assets on the ground, there are also health and safety implications. Draper adds: “The terrain can sometimes be quite difficult, with the potential for trips and falls. Surveying networks manually has advantages, but generally takes longer, can cause more disturbance, and requires contact with the landowners for the survey, and the tree cutting.”

“Every time you send a team out in the field, there is a health and safety aspect to consider,” adds Robin Tutcher, helicopter unit and tree maintenance manager at National Grid Electricity Distribution (NGED). Tutcher and his team of pilots are responsible for surveying NGED’s electricity distribution network across more than 55,000 square kilometres of rural and urban areas featuring both high voltage and low-voltage networks, 90,000km of overhead lines, 17,000 towers, and 1.4 million wooden poles.

Surveying all those assets by foot would be impossible, so airborne high-definition cameras and light detection and ranging (LiDAR) technology are important parts of NGED’s surveying arsenal. UK Power Networks also uses LiDAR technology for surveying, Draper explains, which provides “only limited visibility” of the low-voltage network. His teams mainly carry out periodic inspections of LV assets on foot. “This is supplemented by customers informing us of any urgent tree-cutting issues that need attention between surveys.”

For surveying low-voltage networks, where it may be technically or economically impractical to use aerial surveying, Cyclomedia specialises in surveying using vehicles equipped with cameras that take 360° panoramic photographs. James Bateman, UK and EU utilities director at the company, explains: “Networks haven’t tended to go down the route of using drones and aerial imagery for these types of surveys, primarily because the poles and cables are located close to roads and houses.

“Drone surveys are great for larger medium voltage and high-voltage assets, which are generally located away from urban areas. More time can also be spent surveying individual higher value assets; you don’t have that luxury with LV.

“From an aerial survey perspective, the detail required for an LV safety inspection cannot be achieved yet.”

Tutcher points out that drones are the subject of a project NGED is working on with the Civil Aviation Authority called ‘Atypical Airspace’ but are currently restricted in usefulness because of line-of-sight regulations. Drones are likely to be especially beneficial for his colleagues on the transmission side, he says, where assets are more linear.

“The nature of our networks is that they are capillary-esque. There are a lot of them going off in different directions. We are 100% looking at what drones can bring to the table. But we are some way off popping them up there to go and survey the network.”

The complexities of LV networks mean that they run across private land and through gardens or other locations used by the public. There’s a health and safety risk in terms of people, especially children, climbing trees that are close to assets, which is why NGED sends education packs to 80,000 schoolchildren a year warning of the dangers. Tutcher notes that landowners with LV assets on their land often don’t want to take trees back as far as the operator desires.

“From an aerial survey perspective, the detail required for an LV safety inspection cannot be achieved yet.”

James Bateman, UK and EU utilities director, Cyclomedia

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