Life on a bike

Why are SMIDSY’s between car drivers and motorcyclists so common?

David Crundall

What’s your background and role?

I’m a Professor of Psychology at Nottingham Trent University, and I specialise in Traffic and Transport Psychology. I have a special interest in vulnerable road users, of which motorcyclists are one, as this group is grossly over-represented in the Killed and Seriously Injured statistics released by the Department for Transport each year.

What are the most common types of accidents motorcyclists are involved in?

The number one collision occurs between a car and a motorcycle, where the car fails to give way to a motorcycle at junctions. Typically this happens when car drivers pull out of side roads into the path of an on-coming motorcycle. Drivers involved in these collisions will usually say they looked down the street but failed to see the oncoming motorbike. Investigators usually find it’s the driver at fault, which often contradicts the  stereotyped view held by the general public that all motorcyclists are thrill-seeking individuals who place themselves in danger.

However, motorcyclists are also commonly involved in loss of control accidents on bends. These are typically single vehicle accidents, often due to incorrect speed for the conditions.

You’ve done a lot of research into SMIDSYs – what are your key findings?

There are three basic reasons that a driver may pull out in front of an approaching motorcyclist:

  • They may fail to even look.

Some drivers may be so preoccupied with reaching their destination on time, they may rely on their peripheral vision to identify oncoming vehicles when approaching a junction. In the worst cases, drivers may not pay any attention to the main carriageway when exiting from a side road.

  • Drivers may look down the main carriageway and actually spot the approaching motorcycle, but for whatever reason they decide to pull out anyway.

Perhaps they think the motorcycle is very far away? Perhaps they misjudge the rider’s approach speed? Or perhaps they are content to use their greater size to force themselves into the road at the expense of other road users?

  • Finally some drivers may look, but never perceive the oncoming motorcycle and therefore make a decision to pull out on the basis of what seems to be an empty road.

The driver performed all the correct actions but, for some reason, (i.e. not the driver’s fault) the perceptual process failed. Does this really happen?

Studies have demonstrated it does. We assume that whatever the eye is looking at reflects what is being thought about, but this has repeatedly been shown to be false.  Just think about a time when you’ve been trying to read a book but something else is on your mind. Your eyes move along the line but you may have to read the sentence several times in order to process what it means. In essence this is a ‘Look But Fail To See’ error when reading a book.

Why do SMIDSY’s occur so commonly with motorcycles?

There are many reasons. The theory I like best suggests that driver expectations are at fault, combined with in-built errors in our visual system (our eyes and brain). Imagine you drive your car up to the same junction every day for the last 10 years. Every day you look left and right: sometimes there are cars approaching, sometimes the road is clear. Your past experience leads you to expect either an empty road, or one containing an approaching car, bus or lorry.

Then, one day, the driver pulls up to the junction and looks to the right. A motorcycle is approaching but, because motorcycles make up such a small number of vehicles on the road (around 1%), the driver may have never seen a motorcycle at that junction, and therefore isn’t expecting to see one.

Errors in our visual system also play a part. Our eyes and brains are more likely to process big, fat objects - like cars - faster than small, skinny objects, like motorcycles. In the first few milliseconds of glancing down the road we may be aware there is something big in the carriageway, coming towards us. We might not know what the hazard is straight away but it catches our attention and causes the driver to keep his eyes on the road for a fraction of a second longer, in order to work out what he’s looking at.

However, as a motorcycle is much narrower, our eyes and brain will take slightly longer to pick it up as something important. The driver does not look for long enough at the approaching motorcycle to really perceive it, because he has already decided there is no evidence of approaching cars and therefore decides to pull out.

Look but fail to see

How can motorcyclists improve their chances of being correctly identified and appraised by drivers?  

Some have suggested that lateral weaving on approach to a junction can create additional motion cues, and draw a car driver’s attention to the rider. This is only a sensible approach if the lateral weave does not create handling problems. Alternatively a rider could slow down to allow the driver more opportunity to perceive him, and to reduce impact speed should a collision occur.

You’ve done some interesting research into the differences between novice and experienced riders, and those who have undertaken further training. What have you found?

There’s been a lot of research into why SMIDSY’s occur from the drivers’ perspective but no research into how motorcyclists approach hazards, such as side roads.

My study analysed motorcyclist speed and road positioning on approach to side-roads in a simulated urban setting using novice, experienced and advanced riders. Riders rode two laps of a route, encountering five side-roads on each lap. On the second lap, a car emerged from the first side-road in a typical ‘looked but failed to see’ accident scenario.

Riders with advanced training were found to rider at slower speeds and place themselves closer to the centre line when approaching side roads with cars waiting to pull out. This provided them with additional space to manoeuvre around a car should it decide to pull out. In contrast, experienced riders chose faster speeds, often over the speed limit, especially when approaching junctions with good visibility.

Following the hazard, riders were assessed to see if they also modified their behaviour at non-hazard junctions. Whilst all riders were generally more cautious after the hazard, the advanced riders were more flexible about adapting strategies to current road demands. The results suggest that advanced training can lead to safer riding styles that are not acquired by experience alone.

This ‘hazard preparation’ is however dependent on the level of traffic in the contraflow lane. Manoeuvring into the path of an oncoming vehicle on the main carriageway would just lead from one danger to another.

motorcycle simulation

Do you ride a motorcycle?

This is a question I am often asked! I have never ridden a motorcycle other than as a pillion passenger. So (they then ask) how can I speak about motorcycle safety without having experienced it myself? My answer? Motorcycling is a highly emotive pastime for those involved, while research is best approached without preconceptions or biases that often arise from emotional involvement with the object of study. Having said that, it’s also important to have as much insight into motorcycling as possible. I have always surrounded myself with advanced-trained motorcyclists when studying this area. I believe that their motorcycling experience and my emotional distance from the activity have lead to a perfect balance for exploring why so many motorcyclists are killed and injured in collisions.

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