The Transport Agency is crediting rumble strips with a 25% drop in fatal and serious injury crashes on roads where they have been installed.
More than 3000 kilometres of the road markings have been laid down since 2007.
The strips, which are fitted in the centre and on the sides of high-risk roads, cause rumbling vibrations and a humming noise if driven on.
The aim is to prevent tired or distracted drivers running off the road or causing head-on collisions.
Transport Agency spokesperson Andy Knackstedt says more rumble strips will be installed on high-risk roads in the coming financial year.
Huge boon for safety, says AA
The Automobile Association says the drop in crashes on roads where rumble strips are installed represents a huge boon for road safety.
The AA's motoring affairs general manager, Mike Noon, says the rumble strips as close to being a silver bullet for road safety as it gets.
He says the noise has the effect of slightly slowing speeds, they greatly improve lane keeping and also alert sleepy drivers if they drift across the highway.
Mr Noon is welcoming the fact that the rumble strips will be installed on roads where the accident rate is high.