Index of fatalities by motorcycle and pillion riders vs fatalities for all modes, Australia (source data: BITRE)
Index of road fatalities by motorcycle and pillion riders vs fatalities for all modes, Australia. 2016 figures based on extrapolation of first six months data (source data: BITRE)

Five motorcycle riders died on Victorian roads last week bringing the total to 41 so far this year. The Age reported on the weekend that “riders have never made up such a large proportion of Victoria’s road deaths”.

So what’s going on here; has motorcycling suddenly become permanently more dangerous? Are more riders taking drugs? Do lower petrol prices mean there’re more car drivers threatening motorcyclists? Is climate change implicated in some way?

The Bureau of Infrastructure, transport and regional economics‘ (BITRE) database of road fatalities shows 35 motorcyclists died on Victoria’s road in the first seven months of this year, compared to 17 for the corresponding period last year. They only make up 4% of Victorian vehicle registrations, but so far this year motorbike riders account for 20% of deaths.

Motorcycle death have increased in NSW too, although not by as much as in Victoria. In the 12 months to end July this year, 37 motorcyclists died on NSW roads compared to 33 for the corresponding period in 2015.

They’ve also increased when looked at across all states and territories; there were 120 motorcycle deaths nationally in the first half of this year compared to 94 in the first six months of last year; most of that difference though is due to the high death rate in Victoria.

I’ve taken a look at the historic pattern of motorcycle fatalities at the national level and compared it with total road deaths i.e. for all modes (see exhibit). In both cases I’ve extrapolated the trend for the first six months of 2016 to the full year.

The index indicates both motorcycle and total road deaths edged up since 2014 but they’re still within the bounds of the long-term pattern that’s held since 1992. Even if the full year does sustain the unfortunate trend set in the first half of 2016, it won’t exceed the death toll in 2008. At this stage, the increase in the first half of 2016 looks like a fluctuation rather than a permanent shift.

Bear in mind too that motorcycling has steadily gotten safer in “real terms”. For example, the estimated number of motorcycle riders registered in Australia increased from 678,790 in 2011 to 828,965 in 2016. Note also BITRE estimates kilometres of travel by motorcycle in Australia’s capital cities grew from 0.71 Billion kilometres in 2000-01 to 1.46 Billion kilometres in 2013-14.

There are various reasons why the number of fatalities might fluctuate at the margin from year-to-year e.g. economic conditions, weather conditions.

Perhaps the good weather enjoyed by Victorians earlier this year attracted more riders on to the state’s roads, especially inexperienced recreational riders. The Bureau of Meteorology says last summer was the third-warmest on record, with both daytime and night time temperatures well above average. This was followed by the warmest autumn on record, with warm to mild temperatures lasting well into May.

If there’s substance to this explanation, it suggests climate change could induce an upward trend in fatalities albeit with continuing fluctuations from year to year. At this point though there’s no compelling reason to conclude there’s a permanent increase in the risk of dying while motorcycling.

Hopefully the trend for the first half of 2016 won’t hold for the second half and the year will finish better than my simple extrapolation suggests; I expect it will.