This is a guest post from Glen Koorey. He is a senior traffic engineer and transportation planner with ViaStrada Ltd in Christchurch. He specialises in road safety and sustainable transport, with a particular focus on speed management.
Last September, I was holidaying in Victoria, Australia, driving around the Great Ocean Road. This winding two-lane scenic highway is similar to many of New Zealand’s rural roads. Interestingly though, most of it was signposted at 80km/h and a few of the trickier bits were even 60km/h. A similar approach was taken with many other rural side roads we encountered.
Sure, they also have a few 110km/h freeways but, with this kind of safety-first approach, it doesn’t surprise me that Victoria has a road fatality rate per capita more than 30% less than New Zealand’s. And for similar reasons, we need to take quite seriously the role of lower speeds in reducing our appalling road safety numbers.
In the current public debate about our increasing road deaths, many people have been quick to suggest all kinds of “solutions”. In particular, a lot of comments concentrate on improving either our road standards or the behaviour of our drivers. While both worthy aims, their primary focus is on reducing the number of crashes. However, a “safe system” approach to road safety is more interested in reducing the numbers of deaths and serious injuries (which is a combination of both the likelihood and severity of crashes), and that requires focusing on different things.
For example, straightening a winding road may reduce the number of crashes, but is often rather costly (and any remaining crashes may be more severe due to higher speeds). Conversely, installing low-cost barriers in the median and edges may not reduce crashes but reduces the severity of them by preventing head-on and run-off road collisions.
The practical reality is that we are dealing with a system that involves imperfect human beings, and our transport improvements budget is always limited. Therefore, there will always be some people who make a mistake or bad judgment, and there will always be roads of lesser quality. Improvements in these matters will not happen overnight either. That’s where lower speeds can improve crash outcomes now, even when other parts of the system aren’t perfect.
Speed gets a bad rap in this country, with people complaining about Police enforcement and reduced tolerances. These get pointed to as demonstrating why a focus on speed doesn’t improve safety. However, the Police are working within a system that still currently allows far too many roads to have speed limits well above what is safe for their environment.
Last month, the media reported on a crash near Burnham, resulting in two people hospitalised. The intersection crash site features dynamic speed signs that display a lower speed limit when a car approaches on the side-road. Now, one driver evidently failed to give way and shouldn’t have done that. And perhaps a re-designed intersection may have reduced the chances of this crash happening. However, irrespective of who or what caused the crash, the slower speeds asked of the main road driver evidently contributed to the outcome not being a fatal one.
This “safer speeds” approach is very prevalent in Europe, and explains why jurisdictions there are amongst the safest in the world in terms of road safety. Many European countries have 110km/h motorways (or higher), but their other rural roads (the bulk of their network) have limits of 60-80km/h. And in urban areas, 30-40km/h local streets are a core part of where people live, work and play. These examples should be emulated in New Zealand.
But we don’t even have to look overseas for evidence of the effectiveness of lower speeds. In New Zealand, we had our own natural experiment when the open road limit was reduced to 80km/h in 1973 and subsequently increased to 100km/h in 1985 (in both cases, with no change to the road network). Even accounting for other changes in traffic patterns and road regulations at the time, there was a clear reduction in rural crash casualties following the 1973 speed drop, particularly for fatalities (down 37% in the first year). Conversely after the 1985 increase, there was a similar uptick in crash statistics, particularly rural fatalities (up 23%).
It may not be prudent to advocate a blanket reduction in open road speed limits again, but clearly there are many sections of rural road that are totally unsuited to a 100km/h limit (NZ Transport Agency’s speed management data also tells us that the calculated “safe and acceptable speeds” for these roads are typically 80km/h or less). Without median protection, a head-on collision at these speeds is very often unsurvivable. While it may be cost-effective on our busier arterial routes to introduce such protective features for a 100km/h limit, for many local roads that is completely untenable within available roading budgets – far simpler to have motorists slow down.
Will simply introducing a lower speed limit on its own change traffic speeds? Typically, for every 10 km/h posted speed limit reduction, mean speeds drop by 2‐3 km/h. That might not seem much, but international research has found that a 1% reduction in speed generally results in a 2% reduction in injuries and 4% reduction in fatalities. So even a 5km/h drop in rural speeds (say, from reducing posted speeds from 100 to 80km/h) could mean 10% fewer injuries and 20% fewer fatalities there.
Lower speeds can make real improvements to both the likelihood and severity of traffic crashes in New Zealand. It’s not a remedy for all problems but, at a time when our road safety record is worsening, it’s a key tool that we haven’t made good use of yet. It’s time for all road controlling authorities to identify what parts of their network would greatly benefit from introducing lower speed limits.