Recent legislation banning the use of handheld phones by drivers had basically no effect on the number of road accidents, according to a new study.

“If it’s really that dangerous, and if even just a fraction of people stop using their phones, we would expect to find some decrease in accidents,” says professor Daniel Kaffine, who worked on the analysis. “But we didn’t find any statistical evidence of a reduction.”

It seems that Kaffine and his colleagues took steps to iron out at least the most obvious extraneous factors. We are told:

The researchers chose to look a relatively narrow window of time to reduce the number of other variables that might have an impact on accident rates, including the possible introduction of safer cars into the market, an economic recession that leads to a drop in overall driving, or other changes to state traffic laws. They also corrected their data to account for precipitation, which can cause more accidents; gas prices, which can affect how many vehicles are on the road; and other unobservable factors that may have influenced accidents.

Once all these corrections had been made, the effect of banning handheld phone use at the wheel was found to be ... zero.

"Our results suggest that simply banning hand-held cellphone use may not produce the desired increase in traffic safety," comments Kaffine, bluntly.

The ban in question was the one brought in for California in 2008, but obviously the study would seem to have implications for other bans in other major car-using jurisdictions with broadly similar levels of road safety, law enforcement and compliance with laws and regulations.

Possible reasons for the complete failure of the ban to achieve anything useful could include it being totally ignored by all drivers, but this seems unlikely based on previous studies: at least some people pay attention to such bans, and so a noticeable number of accidents should be prevented.

It could also be that most who obeyed the ban switched to the use of handsfree equipment, which some believe is just as dangerous as handheld. Or it might be that those who obeyed the ban turned from nattering on their phones to groping about below the windscreen to manipulate their car audio systems, satnavs etc.

But it has to be at least possible also that actually using a phone while driving just isn't that dangerous. Various academic studies have put it on a par with drunk driving, but Kaffine and his team note that many of these studies were lab based and may have failed to reproduce the way people actually behave behind the wheel.

The new study can be read here, in the journal Transportation Research Part A: Policy and Practice. ®