Mt Maunganui speed and safety review


30kmh signViaStrada was commissioned by Tauranga CC to assess the effectiveness of the 30 km/h zone in Mount Maunganui, in terms of vehicle speeds and crashes, taking into account the changes in traffic volumes that have also occurred since its introduction in August 2011. A control zone immediately south of the study area, where the 50 km/h speed limit remained unchanged, was used as a basis for comparing general changes in the area. Five years of speed, volume, and crash data before and after implementation were used to analyse the effects.

Mt Maunganui analysis zone
Study and control zones for Mt Maunganui 30 km/h area


The analysis found that:

  • Traffic volumes increased in the 30km/h zone by +6%, compared with a decrease in the adjacent control zone (-12%).
  • Traffic speeds showed no notable change in the two years immediately before/after the change; however, there was an ongoing downward trend in mean and observed speeds over a 5-year time frame of about -7%, and mean speeds were already below 30 kmh.
  • The expected number of crashes in the 30 km/h zone (based on the change in traffic volumes) fell by 21% in the 5 years before/after, compared with a 1% drop in the control zone. However, this finding is not (yet) statistically significant.

Plot of crash results

It appears that implementing the 30 km/h speed zone has had a positive effect on traffic safety, despite traffic volumes increasing slightly, and contrary to the trends displayed in the neighbouring control area.

Project Objective
Assess the safety (and other) effects of introducing a 30km/h zone to the Mt Maunganui commercial area
Tauranga City Council
Mt Maunganui, Tauranga
Safety analysis report
Project Status
Key contact