What the aerial surveys looking for
In a prevoius life i was involved with investigating reports from the Aerial survey section of BG.
Basicaly any heavy plant parked anywhere near the NTS is potentialy a hazard.
These pipes are identified by Orange and white marker posts on road crossings.
The size of pipe can be up to 48 inch and run at up to 70Bar so any leak would be serious.
So if a Large tracked vehicle / digger suddenly turns up in a field near the NTS expect a visit.
regards
P