The number of fixed average speed cameras on British roads has more than doubled in the last three years, according to recent research by Road Safety Analysis.

Commissioned by the RAC Foundation, the research found that between 2013 and 2015, new average speed cameras had been installed on more than 137 miles of British roads, and now cover a total of 263 miles across the UK.

This increase includes the introduction of 12 new speed check routes, including routes on the A614 in Nottinghamshire, the A9 between Perth and Inverness as well as sections of the A537 in Cheshire and the A465 in mid Wales.

The data did not include temporary average speed camera zones, which are sometimes installed during motorway road works.

Experts have favoured the permanent average speed cameras, which calculate a driver’s speed based on the time taken to travel between two positions on the road, as they are seen as a more cost effective measure than traditional single speed cameras.

Nicky Jackson, serious injury solicitor at Thompsons Solicitors, said: “While it is encouraging to see that more of Britain’s roads are permanently monitored by average speed cameras to help ensure consistent and slower speeds, they alone cannot solve the safety issues on our roads.

“Having more average speed cameras is a step in the right direction, especially on roads that have high accident rates, but they play only one part in the bigger road safety picture.

“Between 2010 and 2015, we saw a significant drop in the presence of road traffic police in various parts of the UK, with reductions in Durham, for example, as high as a third.

“Without adequate policing of the roads, cameras may mean it’s possible to determine an increased percentage of the road network average speed, but measures such as the drug driving legislation won’t be properly enforced.

“To tackle Britain’s road safety problems, we don’t just need more average speed cameras but visible, real policing, and that means adequate resources.”