Here’s why we need to slow down
Auckland Transport Chief Executive Shane Ellison and Brake NZ talk about road safety.
One of the fastest ways to immediately bring down the high rate of deaths and serious injuries on our roads is to set safe and appropriate speeds. The default 50km/h for urban roads and 100km/h for rural road roads are not fit for purpose. They do not consider our challenging road system where fatigue, a mistake, distraction or a poor choice made behind the wheel can lead to devastating consequences. And it doesn’t have to be this way. We do not have to accept “some deaths or serious injuries” as a price to pay for our mobility.
Speed determines both the likelihood of a crash occurring and the severity of the outcome. Regardless of what causes a crash, whether people walk away or are carried away will depend on the speed their vehicles are travelling. Our crash stats show 80% of all death and serious injury occurs on 50km/h local urban roads and 45% of all local urban death and serious injury involve vulnerable road users (people walking, people on bikes, people on motorcycles, children, the elderly and the differently abled – people not in cars).
It is not just about keeping the driver and passengers of a car safe. While modern cars have improved safety features, if we crash into vulnerable road users at speeds higher than 30km/h, the risk of them dying or being seriously injured increases greatly.
For individuals, the risks of a severe crash might seem small, but from a collective societal point of view, if every driver reduced their speed by 10km/h on urban roads, the safety gains are substantial across the whole road network.
Research on common driving journeys around New Zealand shows that the impact of lower more survivable speeds is marginal on overall journey time across the users entire journey.
Research Report 582 Time and fuel effects of different travel speeds - page 41, section 2.3 – Auckland short route study
We can’t outrun physics
We humans are fragile and vulnerable creatures. Our bodies can only withstand low impact forces – the equivalent of running on foot into a wall and falling. We are not designed to withstand the high impact forces involved in vehicle crashes.
Speed dictates what happens when the vehicles we drive crash into other cars and into other vulnerable road users. The probability of a person walking or cycling being seriously injured or killed increases rapidly with relatively small increases in speed.
Alternatively, a reduction in vehicle speed from 50km/h to 30km/h translates to a 90% chance of surviving the crash (if a vulnerable road user outside the car gets hit directly at 30km/h).
*Survivability rates vary significantly based on a number of factors and scenarios. AT takes a preventative approach with respect to the survivability of our most vulnerable road users. Data taken from Research Report AP-R560-18 published in March 2018 by Austroads - the Association of Australian and New Zealand Road Transport and Traffic Authorities.
A small increase in vehicle speed also has an immediate corresponding effect on the braking or stopping distance.
If we need to stop suddenly, we have to take into account this stopping distance i.e. the time it takes for us to react to the sudden change in the driving environment, the distance our vehicle will travel from the point when brakes are fully applied, to when our vehicle comes to a complete stop.
The current speed limits on most of our roads are not suitable for the existing conditions. Many of our rural roads are twisting and hilly with narrow unforgiving lanes that pose challenges to even the most experienced drivers. The consequences of small driver errors on such roads can be fatal.
Caption: Stopping distances based on an average driver in a car with good tyres and dry conditions.