A 4kmh threshold before police issued tickets over summer slowed speeds, cut road deaths, and is about to return for Easter.

Police ran a two month campaign in which they handed out tickets to anyone travelling more than 104kph.

A preliminary analysis shows the proportion of drivers going more than 100kmh was up to 51% lower than during the previous four summers.

In the two months there was a 26% reduction in road deaths – helping give 2013 the lowest road toll in 60 years.

Police say the 4kmh threshold will be back for 11 days over Easter from next Thursday.