There has been much discussion and debate about the causes and solutions to the road crash rate in New Zealand. The above left-hand graph shows a recent report by the International Transport Forum analysis of the number of fatalities (people) from road crashes. My analysis of the long-term trends of the number of fatal crashes (vehicles) since 2000 (right side), show a very different picture to the distorted and cherry-picked version on the left.

To better understand the issue, I decided to examine the evidence. After analysing the data from 2000 to 2022, I found the following:

Figure 1 shows a continuous linear decline in the crash rate, with an annual decrease of 1.25% (or 4.7 deaths). Although the R-squared value is less than 50%, more information is available below.

Figure 2 displays the economic indicators, including the amount of travel (measured in vehicle kilometres travelled or VKT) and the gross domestic product (GDP). Both values are normalised to 2001. The figure shows that the amount of travel lags following major economic events such as the 2008 Global Financial Crisis (GFC) and the COVID-19 pandemic.

During the GFC, travel was suppressed until around 2013, after which it peaked in 2018. This increased exposure to traffic coincided with an increase in crash fatalities. On the other hand, the COVID-19 pandemic had a different impact. Despite a significant financial stimulus, the amount of travel did not increase as much as during the GFC. The crash fatality rate in 2022 increased only slightly above the trend due to the lagged COVID-19 stimulus.

Figure 3 shows the fatal crashes with 95% Confidence Intervals and reveals that up until the GFC in 2008, the trend was stable, with fatal crashes continuing a downward trend. After the GFC, the amount of travel decreased, and the fatal crashes dropped even lower than expected. However, the crash rate increased again over 2-3 years (2017), returning to the normal expected variation until the pandemic hit.

Figure 4 combines the economic and fatal crash trends. It suggests that even if we did not change current policies, the trend would likely continue to decline yearly, with normal yearly variation around the mean downward trend.

Do we need to jump up and down about 2022? Probably not, given that inflation and the impending recession are likely to drop that rate right back into the expected and continuing downward trend, probably even lower.

The graph also shows two trend lines, linear and polynomial, that predict that it will drop even if we do nothing different. This is why we should not succumb to the annual outcry of “this year is so much worse than last year, therefore we need …”. Overall, despite more people and more travelling over 20 years…. the crash rate continues its downward march due to ongoing initiatives in vehicle safety and infrastructure improvements. Additional and stricter enforcement and advertising, as evidenced by the Safer Summer campaigns from 2010 onwards, have had no statistically significant effect. So, are we looking for the right solutions for the next big SEATBELT reduction effect on fatalities and serious injuries?