Lowering the speed limit is one of the ways we can create safer roads for all users.

car driving round a bend in the road

Speed dictates both crash probability and severity – the higher a vehicle’s speed, the greater the risk of a crash and the bigger the consequences are upon impact.

The speed you’re travelling at can mean the difference between life or death for drivers, passengers, pedestrians and cyclists.

As humans, our bodies are not designed to tolerate the high-speed impact of crashes.

Collision speed and crash severity

The OECD’s International Transport Forum Speed and Crash Risk(external link) report outlines the relationship between speed and crash occurrence/severity.

It shows that if impact speed increases from 30 to 40 km/h the risk of fatal injury to a pedestrian or cyclist is about doubled.

Other internationally adopted research supports the recommendation that relatively small changes in speed can have a high impact on crash survival rates. 

The following chart provides guidance on survivable speeds, based on the impact of a passenger vehicle crashing into another road user at various speeds. A 10% threshold of the probability of a fatality is shown for illustrative purposes:

Graph of the relationships between collision speed and fatality probability

Graph from Research Report AP-R560-18 published in March 2018 by Austroads – the Association of Australian and New Zealand Road Transport and Traffic Authorities.

We have a wide range of roads with varying speed limits throughout Christchurch and Banks Peninsula.

30km/h speed limit sign

Select central city roads have a speed zone of 30km/h

We have a 30km/h speed zone within the Central City due to the high number of vulnerable road users – cyclists, pedestrians and scooterists –  that use this space. 

The impact on your journey time with a 20km/h speed difference is very small but the consequences can be major.

We're also carrying out various public consultations about lowering speed limits on select local roads. 

For example:

  • Teddington Straight is 1.8km long. At 100km/h it takes 65 seconds to travel the length of it while at 80km/h it takes 81 seconds – only 16 seconds more.
  • Montreal Street’s 30km/h section is 1.1km long. At 50km/h it takes 79 seconds while at 30km/h it takes 132 seconds – less than a minute (53) seconds longer to drive through there.

It takes less than a minute of your time to travel at a speed that could mean the difference between life and death if a crash was to occur.

While we may have the legislative power to reduce speed, you also play a part in ensuring the road is safe by driving within the speed limit, and to the conditions.

Cars driving along a roadWe understand you may be frustrated by having to drive at 30km/h instead of 50km/h in the central city. You might be running late or need to get somewhere fast.

But did you know the traffic lights along our network are programmed to the speed limit?

If you drive 50km/h instead of 30km/h you’ll just spend longer waiting at the red lights – plus you’ll have an increased chance of serious impact with another road user.

While the risk to you of having a serious crash may seem small, from a collective societal point of view, if all drivers reduced their speed by 10km/h on urban roads, the safety gains are large, according to the OECD’s International Transport Forum Speed and Crash Risk report(external link).

Check out some of the common myths around speed on our roads.(external link)