It’s perhaps one of the most flouted rules of the road. Despite bans in many places, more than half of US drivers admit to using a mobile phone at least some of the time while driving, according to a report last week.

So what does the evidence say about the risks? And could a new generation of connected cars make phoning on the road safer?

As long as there have been hand-held phones, there has probably been a desire to use the devices in cars – and as smartphones and tablet computers become more powerful and versatile, that desire is only getting stronger.

“It’s quite a unique situation,” says Stewart Birrell of the Warwick Manufacturing Group at the University of Warwick in Coventry, UK. “Most innovation is first developed by manufacturers and then people can use it. But it’s users who are pushing to be able to use smartphones in cars, and manufacturers are following.”

Perhaps those manufacturers shouldn’t: one estimate suggests 6% of all crashes on roads in the US occur because drivers are distracted by their mobile phones. This equates to about 12,000 serious injuries and 2,600 deaths on US roads each year.

A solution might be to equip cars with technology that can prevent crashes even if the driver is distracted.

Some cars now come with technology that allows drivers to pay less attention to the road – and perhaps more attention to their phones. Adaptive cruise control, for instance, uses radar to automatically adjust the speed of a car so that it matches the speed of the vehicle in front. Automatic lane control systems promise to take care of steering, using the feedback from cameras trained on the road ahead to keep the driver safely in their lane. And collision-avoidance systems rely on lasers and cameras to sense emergencies and avoid the risk of a serious accident.

Increased risk

Perhaps understandably, these devices have their critics. “Manufacturers seem to be aiming to produce hi-tech and hence ultimately fallible solutions to problems that wouldn't exist in the first place if people took proper responsibility for their moral obligations as drivers – to concentrate on what they are doing,” says Graham Hole at the University of Sussex in Brighton, UK.

There is certainly a wealth of evidence that using a mobile phone increases a driver’s risk of being involved in a crash – whether those phones are handheld or hands-free. Some studies suggest either type of phone quadruples the risk of crashing. Other studies, however, disagree. A year ago, for instance, social scientists concluded that using a mobile phone need not raise the risk of a crash if the driver makes the call late at night when traffic is thin. Another study last year went even further, suggesting that phone conversations can lessen the risk of a crash if a driver is fatigued.

“Driving can be boring, and if you’re driving late at night when there’s little traffic around you might get tired and switch off,” says Birrell. “If you give people a secondary task at these times of cognitive underload it might improve their driving performance – although the secondary task has to be sensible.”

Few can doubt that there are times when drivers should avoid taking or making a call: driving demands our full attention at a busy intersection, or near a school at the end of the school day. But studies show that in other, less demanding situations, driving may tax only between 50% and 70% of our attention – suggesting, that at these times, we might have plenty of 'spare' attentional capacity to direct elsewhere.

Birrell’s research reaches a similar conclusion. He recently co-designed a smartphone app called FootLITE that, among other things, provides visual warnings to the driver if they are drifting out of their lane or getting too close to the car ahead. In tests with the app running on a smartphone mounted on the dashboard, Birrell found that drivers spent around 4% of their time glancing at the app – but they also spent the same amount of time glancing at the road or in their mirrors as drivers not using the app. Even if it’s at a subconscious level, drivers may interact with in-car technology only when it is relatively safe to do so.

Crash calls

The trouble is, drivers may not apply this criterion to phone use. Paul Green at the University of Michigan in Ann Arbor looked at crash statistics released by the National Police Agency of Japan – they suggest 45% of phone-related crashes occur when the driver is receiving a call. Green thinks people tend to abandon any task – even focusing on the road while driving – in an effort to answer a ringing phone. If this lapse in attention comes at a critical point that demands the driver’s full attention, they run the risk of crashing.

This may be why talking to car passengers is less risky than talking to someone on the phone, says Green. A passenger is more aware of the road conditions and may stop talking when those conditions become demanding.

With that in mind, perhaps one in-car device above all might help people stay connected without compromising driving safety: a workload manager. Such a device would act like a virtual passenger, pooling all the information made available through sensors – the car’s speed, its location on the road network and the time of day, for example – to decide whether or not to distract the driver with information, including phone calls.

Some cars already have basic workload managers. Volvo, for instance, has introduced technology which blocks phone calls when the driver is turning or changing lanes. As cars join the internet of things and become connected to each other and to the world around them, workload managers could become better at identifying critical times where the driver shouldn’t be distracted.

Birrell says vehicle-to-vehicle communication could tell the car whether the road ahead is busy with traffic, for instance, while vehicle-to-road communication could warn if the traffic lights the driver is approaching are about to change. Both situations might trigger a workload manager to block calls. “If the information is used to improve situational awareness, that’s a positive thing,” he says.

But the information from vehicle-to-vehicle communication may be used differently. Manufacturers may be tempted to use it to automate even more of the driving process and lighten the driver’s workload further. Both Birrell and Hole think such a move is unwise. “It could be argued that since many humans are not very good at driving, it might be better to relieve them of the task as much as possible by automating it,” says Hole. “However it will be many years before computing systems are able to process visual information as skilfully as a human.”

Until driverless cars are ready for mainstream use, Hole says motorists will have to accept ultimate responsibility for their actions on the road – which means they might have to get used to cars that talk to other vehicles in order to prevent drivers talking on their phones. As Hole says: “The solution for drivers who don't want to bother paying attention to their driving is: get a bus.”

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