Human error is a frequent contributor to road traffic collisions, understanding the human factors provides a deeper insight into road-user behaviour.

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Archive for February, 2011

The Anxiety Factor

Thursday, February 3rd, 2011

While some people feel very comfortable behind the wheel and very much enjoy the driving experience, other people can feel very anxious when driving. Why do some people find that driving makes them feel this way? Does this anxiety influence their driving behaviour? And can this anxiety be reduced to help people feel more confident and thus improve driving safety?

Research examining driving anxiety has typically examined two groups of anxious people: those who become anxious after a specific traumatic incident such as a car crash and those who are prone to driving anxiety with no specific cause. One of the key researchers in this area is Dr Joanne Taylor from Massey University in New Zealand. She has found that there is actually little difference in driving behaviour and levels of driving anxiety between these two groups.

There are, however, differences in driving behaviour between those who have driving anxiety and those who do not. Taylor’s research has shown that people with driving anxiety are likely to have a number of counterproductive driving behaviours, such as driving too slowly or slowing for unnecessary reasons. Additionally, anxious drivers are more likely to make mistakes whilst driving.

Ironically, it’s therefore possible that people are so anxious about driving that they overcompensate in changing their driving behaviours, which in turn increases the likelihood of being in a collision, which then further increases anxiety.

A recent study by researchers from the Universities of Buffalo and Memphis in the US identified three distinct areas of driving anxiety.

The first aspect of driving anxiety is deficits in performance, such as finding it difficult to stay in the correct lane or forgetting the correct route to take. The second type of driving anxiety is exaggerated safety behaviour, mainly driving in an overcautious but dangerous manner, such as driving too slowly. Hostile or aggressive behaviour is the third type of driving anxiety, which might include shouting or swearing at other drivers when nervous.

The researchers then examined how each type of anxiety might be related to different aspects of driving behaviour. They found that people who tend to report deficits in driving performance due to anxiety, report being less skilled as a driver, avoiding driving and a tendency to become angry when driving.

Those who drive in an overcautious way are likely to avoid driving entirely, but report good driving skills and low levels of driving-associated anger. Finally, hostile anxious behaviour is, perhaps not surprisingly, associated with high levels of driving anger, but it’s not associated with either driving skill or driving avoidance.

People may become anxious whilst driving either due to a traumatic experience or more simply because of their anxious personality tendencies. It’s also clear that there are different aspects of driving anxiety and each of these is differently associated with driving skills and behaviours.

Whilst anxiety may appear to have a very negative impact on driving, it’s important to remember that this is likely only to be true for people who have very high levels of anxiety already. For most people, low levels of anxiety and fear are actually necessary to maintain safe driving behaviours. If drivers had no fear or anxiety they would probably drive in a reckless manner and many incidents and collisions would occur.

For people who do suffer from extreme anxiety, there is help at hand. Targeted fleet driver training is the obvious way to improve knowledge, brush up on skills, boost confidence, and reduce the amount of anxiety experienced.


Dr Victoria Bourne  (BA Hons, DPhil)

Consultant to Driving Risk Management Limited

Drugs and Driving

Thursday, February 3rd, 2011

The effects of alcohol on driving behaviours are well known and the legal limits are clear and well publicised. The consequences of drug use on driving behaviours are not as widely understood, but with recent advertising campaigns (the “wide eyed” advert) and celebrities being arrested for drug-driving, levels of publicity are increasing.

After alcohol, cannabis is the most frequently detected drug found in the blood of motorists who have been involved in a collision. In a recent journal article, Andrew Sewell and colleagues from Yale University reviewed a large number of studies examining the effects of cannabis on driving. Experimental lab-based studies have shown a wide range of impairments in driving skill after cannabis use, including reduced reaction times and psychomotor skills, and difficulties in maintaining attention and tracking objects in the environment.

Interestingly, although cannabis use clearly has a detrimental effect on driving skills, research has shown that drivers who have consumed cannabis are more cautious in their driving. A number of studies have shown that people who have used cannabis drive more slowly and leave larger gaps between their car and the car in front of them. Such findings, however, contradict the conclusions of other researchers who have suggested that individuals who use cannabis are likely to be “risk takers” and therefore are more likely to be involved in an incident.

Returning to Sewell’s review, they emphasised the dangers of driving after the consumption of both alcohol and cannabis. Each drug impairs driving skills in distinct ways. Cannabis use reduces the more “automatic” driving skills, aspects of our driving behaviour that we do not consciously put effort into, but has less of an effect on tasks that require conscious concentration and processing (such as negotiating a junction). In contrast, alcohol consumption has more of a detrimental effect on complex tasks that require conscious and focussed processing. Consequently, driving after the combined use of alcohol and cannabis has far more than just double the risk of using either drug in isolation.

Alcohol and cannabis are not the only drugs known to influence driving behaviours. There is relatively little evidence looking at the effects of cocaine use on driving skills and the research that has been done tends to suggest that the use of cocaine does not have a direct influence of driving behaviours. There are, however, indirect impairments to driving behaviour following cocaine use, due to the short term changes in temperament and long term changes in personality. The increased feelings of euphoria and invincibility that are associated with cocaine use are likely to have an indirect, but very real, influence on driving behaviours, leading to high levels of risk taking.

It is clear that the use of drugs before driving has a negative impact on driving skills, but there is relatively little publicity regarding this. For alcohol consumption there are clear guidelines regarding the number of units that may be “safely” consumed before driving. Given that drugs such as cannabis and cocaine are illegal, a “zero tolerance” approach is the only real recommendation that can be given. However, the effects of drug taking on driving should be more widely publicised and included in driving education schemes, so that individuals have a full understanding of the potentially disastrous consequences of driving after drug taking.


Dr Victoria Bourne (BA Hons, DPhil)

Consultant to Driving Risk Management Limited