Reduction in speed

Image of a safety camera near a school

There are various reasons why people speed. Some are simply excited by driving fast.They can be easily affected by motoring magazines and programmes that highlight the top performance levels of some vehicles.

Motorists in general simply regard the breaking of speed limits – at least in a minor way – as not a very serious matter. Those caught speeding are considered to be ‘unlucky’. But the consequences of driving too fast can be very serious. Being involved in a collision can result in death or serious injury.

Successive governments have set targets to reduce road accident casualties and it is clear that, increasingly, these cannot be achieved without reducing the number of people killed or injured as a result of speed. Long term publicity campaigns are aimed at making
drivers and riders aware of the dangers of excessive and inappropriate speed and the substantial safety benefits that can be gained by even small reductions in speed.

Because the dangers are so severe, a number of measures have been developed to persuade drivers to slow down.
These measures are not always popular but nevertheless they do work.

Road Humps
Road humps in their various forms achieved the biggest mean speed reduction (based on a mean speed before traffic calming of 30mph) -100mm high raised junctions (Commonly known as speed tables, these are large flat topped humps that straddle the entire junction.) achieved biggest reduction of up to 12mph and subsequent likely
accident reduction of 60%.

Vehicle Activated Signs
Vehicle activated signs are predominately used in rural areas. They are an electronic sign that flashes a message to the driver if a predetermined speed has been triggered. Research has shown them to be very effective at reducing speed and collisions at hazards such as sharp bends and junctions with poor visibility. They are also sometimes
used to remind the driver of the speed limit in force. Their effectiveness can be broken down as follows:
-Mean speed reductions at speed limit roundel signs of between 3-9mph
-Mean speed reductions of up to 7mph at junction and bend warning signs
-Mean speed reductions of up to 4mph on safety camera repeater signs
-Overall one-third reduction in accidents at trial sites (Norfolk sites)

Safety Cameras
Nationally, effects on casualties at camera sites:

Both casualties and deaths were down - after allowing for the long-term trend, but without allowing for selection effects (such as regression-to-mean) there was a 22% reduction in personal injury collisions (PICs) at sites after cameras were introduced. Overall 42% fewer people were killed or seriously injured. At camera sites, there was also a reduction of over 100 fatalities per annum (32% fewer). There were 1,745 fewer people killed or seriously injured and 4,230 fewer personal injury collisions per annum in 2004. There was an association between reductions in speed and reductions in PICs.

Vehicle speeds were down - surveys showed that vehicle speeds at speed camera sites had dropped by around 6% following the introduction of cameras. At new sites, there was a 31% reduction in vehicles breaking the speed limit. At fixed sites, there was a 70% reduction and at mobile sites there was a 18% reduction. Overall, the proportion of vehicles speeding excessively (i.e. 15mph more than the speed limit) fell by 91% at fixed camera sites, and 36% at mobile camera sites.

There was a positive cost-benefit of around 2.7:1. In the fourth year, the benefits to society from the avoided injuries were in excess of £258million compared to enforcement costs of around £96million.

The public supported the use of safety cameras for targeted enforcement. This was evidenced by public attitude surveys, both locally and at a national level.

(Source:The National Safety Camera Programme Four-year evaluation Report - December 2005)

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