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There has been a great deal of public comment in New Zealand in recent years about the over-representation of motorcyclists in accident statistics. Not only has it been alleged that motorcyclists are at fault in 87 percent of all accidents in which they are involved, it is also commonly stated that many of these individuals are born again bikers whose mid-life crises have led to them being over-represented in crash statistics, through lack of their ability to ride modern day motorcycles. Such popular misconceptions have had a substantial influence on accident compensation policy and road safety initiatives.

This paper reviews national and international research on motorcycle accidents. It then summarizes a detailed analysis of Transport New Zealand’s (TNZ) Crash Analysis System
(CAS) database. The New Zealand case is then compared with international studies. An examination of the various assumptions made by policy makers is presented, with particular reference to analysis of the crash data. Notably, the results of the analysis highlight visibility as a dominant cause of multiple vehicle accidents involving motorcycles in New Zealand.

Causal Factors in MVMAs V5 HAND OUT 19 May 2010

2 Responses to “Causal Factors of Motorcycle Accidents in New Zealand”

  1. Ross McCorquodale says:

    Conclusions much at odds with what has been otherwise in the media over the last year. Well done. The implication, of course, is that the Auckland and Canterbury figures are representative of the whole country. But a lot more work, by the sound of it, would be needed to make it a comprehensive study of every accident in NZ over the period.

    A similar study of single vehicle accidents is also needed.

    I would like to make some general comments as a lapsed motorcycle rider. Riding any sort of two-wheeled vehicle on the road lost its enjoyment for me many years ago. There are just too many idiots driving cars. Also I have enough trouble predicting slippery diesel spills, sudden gravel patches, and unmarked holes and roadworks on four wheels as it is. Had I been riding a motorcycle all these years, I know I would have come to grief more than once.

    The times I have been startled by motorcycles are almost exclusively when they overtake me, in traffic, at a great speed differential. I’m looking at where I am going, making sure I don’t run into the often unpredictable traffic in front of me. Sometimes I am planning my own overtaking manoeuvre. Motorcyclists seem to believe that I can expend just as much of my time looking behind me as ahead. More, in fact, since they are riding through my blind spots. And frequently they travel very fast – not only very much faster than any other traffic, but often well over any speed limit.

    Motorcyclists can never take it for granted that they will be seen at any time that they are travelling well beyond the speed of normal traffic.

    The observations on visual contrast are well made. But it is not just motorcyclists and cyclists who need to be made appropriately visible. The whole concept seems to be completely lost on road planners and engineers.

    Signs that are so drab as to be nearly invisible by day become blindingly bright by night. Neither condition is at all helpful, but the dazzling glare from a big, yellow chevron arrow sign on a bend means that the road itself becomes totally invisible – unless high beam is switched off. In which case, the sign can be seen, but the road is still invisible. It’s just senseless…

    Even those unending and often meaningless rows of orange cones have been reflectorised with no thought. Again the actual road surface is obscured because each has two broad, very bright reflectorised bands which send back enough light to conceal all details of the road itself in the glare. Why two bands? Why broad, not narrow? Has nobody in authority ever driven at night?

    Please let us have an appropriate use of reflected light. As pointed out by Wulf, Hancock, & Rahimi, in 1989, contrast, not brightness, is the key – day or night.

    Which leads me to observe that motorcycle headlights are sometimes just as high off the ground, just as bright, and just as poorly aimed, as any big SUV that blinds an ordinary, small car driver like me. If I attempt to look anywhere near the vehicle producing the dazzle, I risk total and perhaps not-so-temporary blindness. So, whether it’s coming from behind or in front, a dazzling headlight compels me to look only at the road directly in front of me. I will not be able to see for sure what the headlight is attached to, nor exactly where or how fast it is moving.

  2. Geoff James says:

    Hi – have just come across your post and we share similar views. I’m passionate about upskilling the motoring public at large, the only truly effective means of addressing the root causes of vehicle accidents.

    You may be interested in my blog posts along similar lines:




    Best wishes and safe riding,

    Geoff James


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