What a lower speed limit would mean

A major international report on road safety has recommended reducing speed limits on the open road to 70kmh.

The report looked at the impact of reduced average speeds on road crash and fatality rates in 10 countries and estimates that ‘‘ . . . a 10 per cent decrease in mean [average] speed leads to 20 per cent decrease in injury crashes and a 40 per cent decrease in fatal crashes’’.

It went on to recommend a speed limit of 70kmh on rural roads without a median barrier. The majority of New Zealand’s roading network falls into this category.

If a 70kmh speed limit were introduced here it would help to curb our rising road toll, but the trade-off would be much slower journey times.

How much slower? This isn’t an exact science, but if the speed limit on open roads was 70kmh, it seems unlikely that the average speed over a journey could be more than 65kmh.

There will always be sections where drivers must drive below 70kmh such as built-up areas and hilly or windy sections of road.

So, with that in mind, we estimated the impact of an average speed of 65kmh on rural open roads on several journeys between main centres in New Zealand.

It’s probable that a 70kmh limit would result in average speeds of less than 65kmh, so the estimated times above can be considered best case scenarios.