National Highways is using drones to photograph and map England's motorways and major A roads in precise 3D detail. The organisation has just finished mapping the entire M25—all 120 miles—making it one of the most comprehensively digitised motorways in Europe.

The reason for using drones is simple: it keeps road workers safe. Instead of having inspection teams stop traffic and work near fast-moving vehicles, drones fly overhead and take photographs. National Highways reports that this significantly reduces the risk to workers on a network where roughly two million vehicles travel every day at peak times. Traditional road inspections require lane closures and workers standing near speeding traffic. Drones avoid much of that danger.

The photographs are combined to create a detailed digital copy—or "digital twin"—of each stretch of road. Engineers can then examine this digital model to spot cracks, monitor damage, and plan repairs without visiting the road repeatedly. For an organisation managing 4,800 miles of motorways and major A roads, a digital model saves time and money.

Flying Over Motorways: The Safety Rules

Flying drones near busy motorways is complicated. The airspace is already used by emergency services; GPS signals can be blocked by terrain and structures; and a drone crash on a live motorway could be dangerous. National Highways has put two safeguards in place.

First, the organisation has set out formal rules for any company operating drones on its behalf. These cover how companies get approval, how they must operate, and where they are allowed to fly. These rules go beyond the basic requirements set by the Civil Aviation Authority, the UK government body that regulates aviation.

Second, National Highways has built a flight management system—essentially a traffic control system for drones. It creates digital no-fly zones, alerts operators if other aircraft are nearby, and requires approval before flights begin. This makes it much less likely that a drone will accidentally fly into airspace where it shouldn't be.

What Comes Next

National Highways is building what's called a "digital twin pipeline": regular aerial photographs that are turned into a constantly updated digital model, which feeds into the systems that keep roads running smoothly. Finishing the M25 shows the idea works, but the full network stretches across the entire country. Expanding beyond the M25 will require more drones, more data processing, and continued coordination of airspace.

One thing worth watching is how UK aviation rules evolve. Currently, drones are restricted in how far they can fly beyond the operator's line of sight—rules exist, but they're still being refined. How quickly these rules become less restrictive will partly determine how fast National Highways can expand its drone mapping programme across the rest of the network.