Hands-free mobile phones might be legal to use when youre driving, but according to the latest overseas research theyre not any safer. Which raises the question of whether fines for using hand-held phones are more about revenue-raising than safety.

According to a study just published in the journal of Traffic Injury Prevention, the banning of hand-held phones could be sending the wrong message to drivers that hands-free phones are safe. In fact any suggestion that hands-free was safer was counter to the preponderance of scientific evidence.

The study carried out by road safety researchers in Virginia in the USA evaluated 125 research projects on driving and mobile phone usage throughout the world. It says the evidence shows that the danger to drivers comes from being distracted by having a conversation, rather than holding a phone.

Two research projects one of them in Perth in 2005 - cross-matched crash statistics with mobile phone billing records to establish whether phones were in use just before or at the time of the accident.

Phone use was associated with a fourfold increase in the risk of a property-damage-only crash or a crash serious enough to injure the driver, the study said. There were no significant differences in increased crash risk by driver age or gender, and hands-free phones offered no safety benefit over hand-held devices.

People having phone conversations while driving whether hands-free or hand-held were shown to have slower reaction times, were less likely to notice traffic signs and more likely to miss traffic signals.

This was because humans had limited capacity to divide their attention between different tasks. This was particular so when using two different senses such as listening to a phone conversation and watching the road and other traffic.

The preponderance of experimental evidence is that phone conversations, whether conducted using hand-held or hands-free devices, affect some measures of driving performance to some degree.

As to solutions to the problem, in my opinion, laws limiting all phone use while driving would be difficult to enforce.

One possibility would be to use technology to make mobile phones impossible to use in cars while moving, except for emergency calls. But it is unlikely the phone industry would embrace such an approach or that tamper-proof systems could be developed.