In a study involving 30 farm workers using quad bikes in South Otago, researchers at the University’s School of Physiotherapy found that those with a tendency to steer uphill, instead of downhill while traversing a left-facing slope, had the most accidents.
Study co-author Dr Stephan Milosavljevic says in examining the ergonomics, the problem of retaining stability on the quad bike in this up-hill, left-slope situation was compounded because the driver had to use their right hand to operate the bike’s throttle on the right of the bike.
“In that situation, it is much more difficult for the person to turn uphill while holding the throttle,” he says.
“Farmers who instinctively already know about this problem will say if you are on a left-facing slope and you have to turn, turn downhill. It is much safer.”
In the past ten years, 48 people in New Zealand have died as a result of accidents on quad bikes. After car accidents, they are the second highest cause of vehicle-related deaths in the rural community.
The Otago researchers set out to analyse the driving behaviour of people who regularly use quad bikes, recognising a need to find out why people lose control of them so frequently.
Of the 30 male rural workers and farmers studied, 19 of them, or 63 percent, had experienced loss of control on a quad bike. They were in their mid 40s on average, and about eight to nine years younger and less experienced than those who did not lose control. They traversed left- facing slopes differently to those who had not come off, tending to drift uphill.
The study, the first to show such findings, has recently been published in the journal Ergonomics. Co-author Dr Allan Carman used a device known as a tri-axial accelerometer, which measures tilt relative to gravity, to analyse the roll and pitch level of the quad bike for each worker during a full working day.
Dr Milosavljevic says the study also found high levels of vibration exposure from riding quad bikes that was potentially damaging to the spine, and which can also contribute to a disturbance of balance. Further research is investigating whether vibration exposure from riding a quad bike will affect a worker’s balance and body position sense.
He and Dr Carman have just completed a second, larger study involving 130 South Otago farmers. This is currently under review and not yet published, but it confirms the vibration exposure issue of the smaller study.
“For the farmers and rural workers involved in this larger study, about 60 per cent experienced back pain, and about half of those could relate this to some sort of farm vehicle use such as a quad bike,” he says.
“We also found that if you are taller and heavier, and tend to drive at a higher speed over uneven terrain, your risk factor for loss-of-control events increases significantly.”
A total of 79 of the 130 farmers studied had experienced at least one rollover or loss-of-control event while riding a quad bike.
“The number of loss-of-control events for each farmer ranged between 1 and 20 – one of the farmers said he’s getting pretty good at diving off,” he says.
Of those events, one in 18 resulted in an injury.
“This study is pretty representative of sheep, beef and dairy farmers working in the rolling hill country of New Zealand,” he says.
A proposal to use the study data on quad bike tilt levels associated with rollovers to develop a tilt warning device to be used on the bikes, and to warn of approaching danger limits, has so far not attracted research funding.
Dr Carman believes a lot more research is still needed to drill deeper into the causes of quad bike accidents.
“We have found associations with slope and turning, but there is still a lot more field research to be done to ascertain further risk factors in rollover events,” he says.
“We also suspect attitudes have a lot more to do with rollovers. For example, we noticed that gung-ho attitudes versus more cautious personality traits were reflected in driver behaviour – so it is unknown whether a tilt warning device would change behaviours.”
Dr Stephen Milosavljevic,
School of Physiotherapy,
University of Otago,
Tel 64 3 479 7193