THE last haven where drivers can creep over the speed limit is being invaded by cameras.

From tomorrow one of Britain’s busiest motorways will be monitored in the first attempt to enforce the 70mph limit.

Until now police have struck only when motorists drive well over the limit on motorways. With their central barriers, gentle curves and grade separated junctions, motorways are considered to be far safer than any other road.

Shortly after midday tomorrow, drivers on the M4 in Wiltshire, between junctions 14 and 18, will face a £60 fine and three penalty points for speeding by as little as 9mph.

Cameras in marked vans will be operated from bridges over the motorway. Police and civilian operators will use laser guns on vehicles when they come within a kilometre of the bridges. Under the rules governing mobile cameras, the vans must be visible from 100 metres. But most drivers will be caught long before they come within that range.

More than half of all cars on motorways exceed the speed limit and a fifth travel at more than 80mph. Existing patrols tend to book only motorists who exceed 85mph.

Last night motoring groups accused the Wiltshire & Swindon Safety Camera Partnership of seeking to raise revenue without offering any evidence that safety would be improved.

Motorways are five times safer per mile driven than the average road and eight times safer than urban A roads. There were 9 crashes per 100 million vehicle kilometres on motorways in 2003, compared with 76 on urban A roads. Most of Britain’s 6,000 speed cameras are on A roads. On motorways they usually enforce only temporary speed limits during roadworks. The southwest section of the M25 has cameras on gantries to enforce the lower speed limit in operation during congested periods.

Under Department for Transport rules, camera partnerships can deploy mobile cameras only on stretches where there have been at least two collisions resulting in death or serious injuries per kilometre in the previous three years.

The Wiltshire partnership, which includes the police and the county council, will argue tomorrow that the casualty rate on the M4 is higher than on the average motorway and meets the level required by the department. There were 18 deaths, 69 serious injuries and 641 slight injuries between junctions 15 and 17 between 2001 and 2004.

Signs on the M4 and approach roads will alert drivers that they are entering a speed-trap area but they will not know where the vans will be parked. A spokeswoman for the partnership said that motorists who slow down for the yellow Gatso cameras before speeding up again would be caught by the M4 cameras: “People aren’t supposed to slow down just because they have seen a camera. They are supposed to slow down because it’s the law.” She said that the trigger speed for the cameras could be as low as 79mph and “could change from day to day”. The exact speed will remain confidential to prevent drivers from setting their cruise controls just below it.

The RAC Foundation accused the partnership of using irrelevant crash statistics to justify deploying cameras. Edmund King, its director, said that the casualty problem on the M4 was caused largely by people driving too close to the vehicle in front, stopping on the hard shoulder, overtaking without checking mirrors and failing to slow down for fog.

ROAD SAFETY

• Motorways account for a fifth of road traffic. In 2003, 184 people died on motorways compared with 1,890 on rural roads
  
  
• The average speed of cars on motorways (71 mph) has remained about the same since 1998
  
  
• The proportion of cars exceeding the 70mph limit was 57 per cent in 2003, up from 54 per cent in 2002

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