Injury is the leading cause of death among people up to the age of 45 worldwide, with injuries sustained as a result of road traffic accidents accounting for more premature deaths than either heart disease or cancer.

Around 1.3 million people die every year, and between 20 and 50 million people become permanently disabled, as a result of injuries sustained in road traffic accidents.

The authors base their findings on the impact of speed cameras, which were first deployed on the major access routes in and out of Barcelona, Spain in 2003.

They assessed the cost effectiveness of these speed cameras between 2003 and 2005, taking account of the initial cost to install and operate them, and those costs attributable to police time, ticketing, and photography for motorists exceeding the prescribed speed limit.

These figures were then set against the costs of medical treatment, damages to property and lost productivity, calculated from figures derived from road traffic accident data in the city of Barcelona for 2003 and 2004.

Based on previous data, it was estimated that there would be 364 fewer road traffic accidents and 507 fewer people injured during the first two years of speed camera operation.

When all these figures were taken together, the authors calculated that the net savings made amounted to 6.8 million Euros, equivalent to £5.96 million, over two years, the bulk of which came from savings on medical treatment and property damage costs.

The authors emphasise that these are minimum costs, and that the savings, are in fact, likely to have been greater -- as much as 23 million Euros (£20.17 million).

"Our results show that the installation of speed cameras on the beltways of Barcelona has net benefits for society even under fairly conservative assumptions," they say, adding that their findings back previous cost-benefit analyses carried out in Canada and the UK.