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Brunel University study finds roadside adverts cause crashes

An ergonomics study conducted by the School of Engineering and Design at Brunel University has found that roadside advertising has a detrimental effect on driver's performance and attention, making drivers more likely to crash. The study is the first time that the effects of roadside advertising have been tested in laboratory conditions, using a driving simulator. External distractions are believed to be responsible for more than 10% of all car accidents . Based on 2005 figures, this represents 27,101 casualties . Despite this, very little academic research has previously been undertaken on the subject.

Dr. Mark Young, Research Lecturer at Brunel University led the study using BUDS (the Brunel University Driving Simulator) to investigate the effects of advertising on 48 experienced drivers. Using the simulator, the team created driving scenarios for Urban, Rural and Motorway roads and monitored participants while they drove each route with and without billboards, in a random order.

Key findings

Adverts cause drivers to spend more time out of lane
The study looked at driver performance and attention. Driver performance was judged by the number of times a driver left their lane, and the amount of time spent out of lane. The study found that the presence of adverts resulted in drivers spending more time out of lane, particularly in motorway and rural conditions.

In motorway conditions, adverts caused drivers to spend more time out of lane than when driving the same course without adverts (0.1 second out of lane with adverts, compared to 0.05 seconds without adverts). In rural conditions adverts caused drivers to spend an average of 3 seconds out of lane, compared to 2.1 seconds without adverts. Although the margins are small in the test, over a longer period of time the risks associated with being out of lane will be increased, and are doubled by the addition of roadside advertising.

Adverts divert attention from road signs
Driver attention was measured by assessing the driver's mental workload and by asking the driver at the end of the route to recall the last road sign they passed and the last advert they saw. Mental workload reflects the degree of mental demands and effort required to maintain driving performance, and was assessed using a subjective questionnaire.

In all road conditions the addition of adverts increased the drivers' mental workload. This meant that drivers were working harder than they should have been in order to deal with the added stimulation from the adverts. As a consequence, drivers would be more prone to overload if the road or traffic conditions became difficult.

The study found that drivers in motorway and rural conditions paid attention to billboards at the expense of more relevant signs, with significantly fewer road signs being correctly recalled in the test compared to adverts. However, on urban roads this trend was reversed. An explanation could be that adverts are more distracting when driving conditions are more monotonous and this should be taken into account when considering advert placement.

Dr Young comments: “Concern about the risk of driver distraction has grown in recent years, but the issue had not been previously addressed with any practical or academic research. Our study aimed to resolve the controversy over whether adverts impact on good driving, and we can conclude that based on our findings, it does.“

“Care must always be exercised by local authorities when approving or placing billboards. In July 06 the UK Department for Communities and Local Government announced plans to revise regulations on outdoor adverts, and we hope our study will contribute to this debate.“

Dr. Young's Paper will be presented at The Ergonomics Society's annual conference in Nottingham, April 17-19, 2007, published in Contemporary Ergonomics 2007 (Taylor & Francis).