Research Evidence on Dangers of Hands-Free Mobile Phone Use whilst Driving

This is the first in a series of three blog posts that aims to assist companies in the development of a mobile phone policy. It will set out the evidence with regards the dangers of using a mobile phone while driving and discuss what a company can do to mitigate the risk.

Mobile phone use has become pervasive in recent years. A Cranfield University roadside observational study of over 7,000 drivers in six cities across the UK found that over 14{5fc9e21ecd349b40961ecfaabf0e965f9efa05e9afba4e3b1e757228720c24ce} were engaged in a distracting activity whilst driving. Using a mobile phone was one of the most frequently observed distraction (Sullman, 2012). The widespread use of mobile phones whilst driving is a particular concern for companies as employees may be tempted to use their vehicle as if it were a mobile office. Companies have a duty of care to manage work related road risk and this includes implementing and enforcing a mobile phone while driving policy policy. Companies must ensure that their employees are aware of the dangers of driving while using a mobile phone and the implications for breeching company policy.

Using a hands-free mobile phone is currently legal in the UK and many fleet-based companies allow drivers to take work-related hands-free phone calls. However, many studies show that hands-free mobile phone use does not reduce the level of risk when compared with handheld and makes little difference to the level of impairment in driving performance or crash involvement rates. This is because the mental distraction and divided attention involved in conducting a phone conversation is responsible for the increased risk. Many drivers consider that a hands-free phone call is just the same as talking to a passenger but research has shown that it is more dangerous (Charlton, 2009). Indeed, having a hands-free device in the vehicle may actually encourage drivers to use their mobile phone while driving more often (Gras et al., 2007).

Indeed, driving impairment associated with using handheld or hands-free mobile phone can be as profound as being at the legal alcohol limit. In a UK driving simulator study, drivers using either a handheld or hands-free mobile phone showed slower reaction times to road signs and missed significantly more road signs than non-distracted drivers. Furthermore, those driving while using a mobile phone had reaction times 30{5fc9e21ecd349b40961ecfaabf0e965f9efa05e9afba4e3b1e757228720c24ce} slower than being at the legal alcohol limit and were less able to maintain a constant speed and keep a safe distance from the car in front. Braking distance also differed between the groups when driving at 70 mph; 102ft for unimpaired drivers; 115ft for drivers at the legal alcohol limit; 128ft for drivers using a hands-free phone and 148ft for drivers with a hand-held mobile phone (Burns et al, 2002). A later US study also found that when drivers were conversing on either a handheld or hands-free mobile phone, braking reaction times were delayed by 9{5fc9e21ecd349b40961ecfaabf0e965f9efa05e9afba4e3b1e757228720c24ce}, the variability in following distance increased by 24{5fc9e21ecd349b40961ecfaabf0e965f9efa05e9afba4e3b1e757228720c24ce} and they were involved in more road traffic crashes than when they were not conversing on a phone (Strayer et al., 2006). It is not surprising then that when researchers have examined injury crashes, mobile phone use while driving was associated with a four-fold increase in crash risk independent of whether the mobile phone was hands-free or hand-held (Redelmeier and Tibshirani, 1997; McEvoy et al, 2005).


Burns, P. C., Parkes, A., Burton, S., Smith, R. K., & Burch, D. (2002). How dangerous is driving with a mobile phone? Benchmarking the impairment to alcohol, TRL Report TRL547. TRL Limited, Berkshire, United Kingdom.

Charlton, S. G. (2009). Driving while conversing: cell phones that distract and passengers who react. Accident Analysis & Prevention, 41(1),160-73.

Gras, M. E., Sullman, M.J.M., Cunill, M., Planes, M., Aymerich, M., & Font-Mayolas, S. (2007). Who uses a mobile phone when in Spain? Accident Analysis & Prevention, 39, 347-355.

McEvoy, S.P., Stevenson, M.R., McCartt, A.T., Woodward, M., Haworth, C., Palamara, P., and Cercarelli, R. (2005). Role of Mobile Phones in Motor Vehicle Crashes Resulting in 31 Hospital Attendance: A Case-Crossover Study. British Medical Journal. BMJ Online First.

Redelmeier, D. A., & Tibshirani, R. J. (1997). Association between cellular telephone calls and motor vehicle collisions. New England Journal of Medicine, 336, 453–458.

Strayer, D.L., Drews, F.A.,& Crouch, D.J. (2006). A Comparison of the Cell Phone Driver and the Drunk Driver. Human Factors, 48, 381-391.

Sullman, M. (2012). An observational study of driving distraction in England. Transportation Research Part F, 15,272-278.