All that changed last week when Wiltshire and Swindon Safety Camera Partnership began operating speed cameras on a seemingly unremarkable stretch of the M4 in Wiltshire. There are now seven mobile camera sites between junctions 14 and 18, approved by the DfT.

Five offences have been recorded since the cameras were installed. Saira Khan of the partnership said: “This is to save lives; it is not because we want to make money. I cannot say what the trigger speed is going to be. What we are saying to motorists is to be aware that if they come through Wiltshire and they break the speed limits they may get caught.”

The partnership said the cameras were justified by the 18 deaths, 69 serious injuries and 641 slight injuries between junctions 15 and 17 of the M4 between 2001 and 2004.

The Strathclyde Safety Camera Partnership, based in Glasgow, argues that a higher than average accident rate between junctions 11 and 13 of the M74 justified its plan to install cameras there this summer.

Motoring groups fear the arrival of cameras could be the beginning of a spread across the motorway network. Specs cameras — which calculate a motorist’s average speed between two points — could be used to monitor whole stretches of the motorways.

The Conservatives have promised a review of the 70mph limit if they are elected. “Motorways are the safest roads in the country,” said Tim Yeo, the Conservative transport spokesman.

“If we look at this in a rational manner we can justify raising the speed limit to 80mph on some stretches of motorway. We want to restore confidence in speed limits and how they are policed.”

Even Richard Brunstrom, chief constable of North Wales police and head of road policing for the Association of Chief Police Officers, who was once dubbed the “mad mullah of the traffic Taliban” because of his zero tolerance approach to speeding, has said he would welcome a review of speed limits. “We need to have a root and branch reform of every speed limit throughout the country,” he said.

Motorways are five times safer per mile driven than the average road and eight times safer than urban A roads. There were nine crashes per 100m vehicle kilometres on motorways in 2003, compared with 76 on urban A roads.

Speed is responsible for 11% of collisions on motorways, according to the DfT. On all roads, excessive speed is the seventh most common cause of accidents, behind inattention, failure to judge another vehicle’s path or speed, “looked but did not see”, careless/thoughtless or reckless driving, and lack of judgment, according to an official study which looked at 54 possible causes of accidents between 1999 and 2002.

National speed limits vary from 55mph in Norway to 75mph in Spain and 80mph in Austria and Denmark. German motorways have no maximum limit unless stated on a few sections. Some organisations, including the RAC Foundation, would support a split system like the one in France, which has a 130kph (80mph) limit in dry conditions, falling to 110kph (68mph) in the wet.

The DfT said there were no outstanding applications for more motorway cameras.

Next week: how to cope with motorway phobia David Newham/Martin Banks

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