The coverage of average-speed cameras on UK roads has more than doubled since 2013, new research has revealed.
The BBC's The One Show found that 51 stretches of British roads are tracked by the cameras, with the total miles covered coming to 263 miles. They vary between systems covering less than a mile, to 99 miles of cameras on a stretch of the A9 between Dunblane and Inverness.
This has risen from the 127 miles recorded in 2013. The cameras were first installed on UK roads in 2000 in Nottingham. The longest stretch currently in England is on the A614 Old Rufford road near Ollerton, Nottinghamshire. It measures a full 12 miles long.
However, these numbers don't take into account the stretches of road that are monitored by average-speed cameras because of roadworks. The analysis also found that some roads were being watched by more than one set of cameras at a time.
Richard Owen, from Road Safety Analysis, the company behind the research, said: "Some of the old fixed-speed cameras have been around for 25 years and they are based on 25mm film.
"They are coming to the end of their life, so as they are replaced they're sometimes getting replaced with average-speed camera systems."