Posted by: wesleyjohnston | January 1, 2015

Northern Ireland Road Deaths – 2014

Note: In this blog I look at road deaths statistically. I am very conscious that road deaths are not merely statistics – every one represents a loved one lost and a lifetime of bereavement. Nothing in this blog is intended to trivialise this tragic reality.

Provisional figures show that 79 people died on Northern Ireland’s roads in 2014, well up on the year before when 57 people died and substantially more than 2012, the lowest on record, when 48 people lost their lives. This is very disappointing and the PSNI and Department of the Environment have already pledged to do their best to reduce this in 2015. The graph below shows the figures for the past twenty years.

Road Deaths Northern Ireland 1995-2014

As you can see, the overall trend was fairly steady for the first ten years, before a decline began from 2004. Over the next ten years deaths on the roads more than halved, reaching a low of 48 in 2012. Since then the figure has increased again, reaching 2014’s figure of 79. However, it is worth noting that despite the upward trend, the number of deaths in 2014 was still the fifth lowest since records began.

So a couple of questions are worth asking:

1. Is 2014 unusually bad, or were 2010-2013 unusually good?
2. Is this trend mirrored elsewhere or is it unique to Northern Ireland?

At the outset we need to say that these figures cannot be explained by the changing number of people on the roads, since this only varies by a percent or two from year to year and is nowhere near large enough to account for such big differences. The explanation must be deeper.

We have to be careful when looking at road deaths statistically because Northern Ireland has a very small population (around 1.8 million) and road deaths in recent years have always been less than 200 per year. With such a small sample size we must expect a higher degree of fluctuation from year to year than would be the case over a larger population, such as Great Britain. Therefore it is instructive to compare road deaths in Northern Ireland over the past twenty years to our two closest neighbouring areas – Great Britain (i.e., the rest of the UK), and the Republic of Ireland. Unfortunately the total number of road deaths in Great Britain in 2014 has not yet been released, so we only have figures up to 2013 for GB. However, the graph below compares the trends in Northern Ireland, Great Britain and the Republic of Ireland over the previous 20 years. Each graph shows road deaths given as a percentage of the 1996-2000 five-year average so that they can be compared to each other (road deaths in GB in 2013 were actually 1713, and in RoI there were 190 in 2013).

Road Deaths NI, GB and RoI, 1996-2014

Looking at this graph it seems that all three areas have seen a very similar trend – road deaths fairly static (or declining slightly) during the first decade, but after 2004, they all fall sharply. Notably, Northern Ireland’s deaths fell most dramatically, out-performing both GB and RoI over this time period before growing again over the past three years, back towards the trend seen in GB and RoI. This suggests that the overall trend is not unique to Northern Ireland but is mirrored elsewhere.

You can also see that the smoothest line is for GB, which is to be expected since it has the largest sample size and is thus less susceptible than NI to the effect of random fluctuations. Thus the GB line is the one that is most likely to be an accurate reflection of the underlying trend, less affected by statistical spikes. The line for NI does seem to broadly follow the GB trend, but, as discussed, it varies much more from one year to the next due to the much smaller population size here.

So the NI graph fell much deeper below the overall trend seen elsewhere, and has since risen again. This suggests that it is more likely that 2010-2013 were unusually good years in Northern Ireland, and that 2014 represents a return towards the underlying trend. This could be an example of the phenomenon known as regression towards the mean.

Nevertheless, the graph also suggests that 2014 was probably higher than average. These statistics suggest to me that the total number of deaths in 2015 is likely to be less than in 2014, but likely to be more than in 2010-2013. So my conclusion is that the increase in road deaths in 2014 is disappointing but probably not quite as alarming as some media reports would suggest. However, at a human level the high number of deaths in 2014 is sobering and should usefully serve to concentrate the minds of both road users and road planners on safety during 2015.

I plan to blog more on the subject of road deaths in the near future. In that blog I will look at what trends we can derive from analysing road deaths over the past three years, 2012-14, concentrating on the patterns for particular groups, for example the type of road user, age, gender as well as road standard and setting.

If you are interested to know more about why road deaths have fallen so much over the past decade, see this blog post I wrote in 2012 where I suggest that the three biggest factors are 1. driver awareness of safety issues; 2. better vehicle safety and 3. better road design.

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