The number of crashes and injuries in the central city has reduced since the speed limit was dropped to 30km/h more than a year ago.
Data compiled by ViaStrada senior traffic engineer and transport planner Glen Koorey shows there have been 17 per cent fewer crashes, and a 22 per cent reduction in injuries.
In March 2016, the city council dropped the speed limit from 50km/h to 30km/h on streets between, but not including, Kilmore, Madras and St Asaph Sts.
The move, which was part of An Accessible City, received mixed reactions. Some said it would slow progress, while others said it would make the area safer.
Dr Koorey, a former Canterbury University transport engineering senior lecturer, has compiled crash and injury data for the area from the last four years.
He gathered the figures from the New Zealand Transport Agency’s crash analysis data to see if there had been a change.
It showed between September 2014 and February 2016, there were 73 crashes in the area, and 36 injuries.
That dropped to 60 crashes since the new limit was put in place and 28 injuries.
In other central city streets that still have a 50km/h speed limit, the number of crashes had increased.
Dr Koorey said the increase could reflect unnecessary traffic shifting, although he had not compared traffic volumes yet so did not want to speculate.
He said because more businesses and shops opening were bringing more people and traffic into the central city, he did not initially expect a drop in crashes.
But Dr Koorey said he was pleasantly surprised.
“It’s early days and I’d like to see how the trends goes for a bit longer (two to three years), but it’s an encouraging sign given that a key reason for introducing lower speeds is for road safety.”
City councillor Sara Templeton said the 30km/h limit not only made the roads safer, but it meant motorists noticed more shops and businesses opening up.
“It was quite controversial at the time, there was a lot of negative comments on social media about that change,” she said.
“What this shows is that the decision was based on best international practice and the local data backs that up.”
The city council has been lowering speed limits in other parts of the city, including along the new cycleway routes.