Fifty years on from the introduction of road-side drink driving breath tests, new research by The Open University and the University of Sussex builds on existing evidence that using a hands-free phone whilst driving can be just as dangerous as drink driving or using a hand-held phone – when using your phone, you are four times more likely to crash[1]. In addition, drivers using hands-free phones may react to less than half as many hazards on the road as undistracted drivers.

The research, led by Dr Gemma Briggs of The Open University, found that dual-tasking drivers took on average 1.6 seconds longer than undistracted drivers to react to unexpected, yet driving related, events. When travelling at 30mph, this equates to an extra stopping distance of 21.46 metres – or the length of five Ford Fiestas parked nose to tail. When unexpected events appear in their peripheral vision, dual-taskers are even less likely to react to them.

Today (9th October) is the 50th anniversary of the introduction of road-side breath testing of suspected drink drivers. Although breath testing and the associated safety campaigns have helped to dramatically reduce the number of drink driving related deaths over the past few decades, the effects of phone use on driving are remarkably similar to those of drink driving, as Dr Briggs explains:

“It’s good that we can accurately measure the level of alcohol someone has consumed and equate that to deteriorated driving. With phone use there is no such easy measure, even though distracted drivers often make the same kind of significant errors as drink drivers. As it’s hard to quantify just how distracting phone use is, and drivers are often unaware of errors they have made, people don’t consider it to be such a serious issue as drink driving, despite a wealth of evidence showing the dangers.”

The experts behind the research are now urging the Government to examine the evidence and legislate accordingly. Although there are tougher penalties for using hand-held mobiles whilst driving, hands-free mobile use is currently legal but just as distracting, according to Dr Briggs:

“Driving is an activity which many of us take for granted, and may feel relatively automatic. As a consequence of this, we tend to rely on our expectations of what ‘normally’ happens when driving. However, when attention is also taken up by a phone conversation, distracted drivers over-rely on their expectations and can fail to notice when something out of the ordinary happens. The distraction of phone use affects a driver’s ability to notice unexpected events on the road, and makes them far less likely to react to things in their peripheral vision, such as a child stepping into the road.”

Kevin Clinton, Head of Road Safety at the Royal Society for the Prevention of Accidents (RoSPA), says:

“There’s a significant distraction risk involved with hands-free mobile phones. Ideally, when the mobile phone law was introduced, it would have covered hands-free mobile phones and made them illegal to use. However, the practical issues of enforcing it meant that it was not feasible to do so.

“We think the law should include hands-free phones. Although it is very difficult for the police to detect drivers using hands-free phones just by observation, they can see if a person’s driving is affected because they are distracted, and for more serious crashes or offences, phone records can be checked.”

Two experiments examined drivers’ reaction times

The research, published in The Transportation Research Journal, involved two experiments to examine people’s reaction times to unexpected events whilst driving. Drivers were asked to react to unexpected events which were either related to driving (e.g. a signpost appearing) or unrelated to driving (e.g. emojis appearing). In the second study, drivers were asked to react to driving events which ran contrary to expectations (e.g. your vehicle stopping at a green traffic light). The aim was to identify if dual tasking drivers relied more on their expectations for ‘normal’ driving than undistracted drivers. Findings included:

1. When an unexpected event appeared in the peripheral area, those using hands-free phones reacted to less than half as many events

2. Dual tasking participants were far less likely to notice events unrelated to driving e.g. the appearance of an emoji on the screen, even when they appeared in the centre of the scene.

3. Dual tasking participants were on average 1.6 seconds slower than undistracted participants to react – at 30mph this is an extra stopping distance of 21.46 metres, or five Ford Fiestas

4. For those events unrelated to driving (emojis), which were detected by dual taskers, phone users were on average 1.3 seconds slower to respond, at 30mph this equates to an extra stopping distance of 17.43 metres, or four Ford Fiestas

5. Drivers using a hands free phone took on average 1 second longer to react to unexpected driving events, such as the car stopping at a green light. That’s an extra stopping distance of 13.41 metres or three Ford Fiestas.

“The impact of attentional set and situation awareness on dual tasking driving performance” was written by Dr Gemma Briggs (The Open University), Dr Graham Hole (Sussex University), Dr Jim Turner (The Open University).