Do average speed cameras really improve road safety

Motorists driving through Dorset will soon need to be aware of average speed cameras (ASCs) as part of a new road safety initiative.

Unlike traditional cameras that record speed at a single point, ASCs use number plate recognition technology to calculate the time it takes a vehicle to travel over a stretch of road, making it harder for drivers to exceed limits intermittently, but do they asctually improve road safety?

National Highways has announced that ASCs will be installed on the mainly single-carriageway A35, east of Dorchester, in the villages of Winterbourne Abbas, Morcombelake, and Chideock. Similar schemes have been introduced elsewhere, including the A420 in Oxfordshire, while proposals for the New Forest were rejected after a feasibility study found they did not meet national criteria.

Speeding remains a major factor in road accidents, and speed cameras have been a feature of UK roads since the early 1990s. First-generation Gatso cameras used radar to measure a vehicle’s speed and captured images on film if limits were exceeded. Over the past decade, many of these “spot” cameras have been replaced with modern ASCs using number plate recognition technology.

Mark Armstrong, head of road safety at Dorset Police, said the force strongly supports the initiative:"Driving at inappropriate or excess speed is one of the 'fatal five' behaviours that commonly cause serious or fatal collisions."

Rospa, the Royal Society for the Prevention of Accidents, also welcomed the plan. Senior policy manager Rebecca Guy highlighted the local impact, noting that over five years, 199 collisions and three fatalities occurred along these roads.

Effectiveness of Average Speed Cameras

Research by the RAC Foundation, published ten years ago, found that the introduction of ASCs led to a 36% reduction in fatal and serious collisions and a 16% fall in personal injury accidents. Steve Gooding, the foundation’s director, said the choice between ASCs and traditional cameras depends on the environment: ASCs work well over long stretches, such as motorways or roadworks, while fixed cameras are more suitable for urban, stop-go traffic.

Impact on Driver Behaviour

Unlike traditional cameras, which can encourage drivers to slow down only at the camera itself, ASCs encourage continuous compliance. Shaun Helman, chief scientist at the Transport Research Laboratory, said most drivers adapt to the system by maintaining safe speeds across monitored stretches.

The AA also supported the scheme, saying ASCs improve traffic flow and are widely accepted by drivers. Jack Cousens, head of roads policy at the AA, noted that while cameras help detect offenders, they cannot identify drivers who speed due to factors like drink or drug use. He emphasised the continued importance of active traffic policing as a complementary safety measure.