"New Zealand's road toll is much, much too high. The Guide, developed as part of the Government's Safer Journeys road safety strategy, is about ensuring all road authorities are making sound, evidence-based decisions with an emphasis on safety."
Mr Williamson said no road in Northland would qualify for an upgrade to 110km/h because none would be able to meet the criteria. He said the top-end speed suited motorways.
"The danger is people see 110km/h as the speed limit and build a tolerance and travel at slightly higher than that. Realistically over a period of time as the road safety authorities come to grips with the speed management guide, we should see speeds reduced in Northland."
Mr Williamson said the biggest issue in Northland was people driving too fast to the conditions, particularly on bends. He said road safety authorities in the region were already getting calls from people living in residential areas for a reduction in speed limits.
The government said the guide combined a range of information to help councils, the New Zealand Transport Agency and other road controlling authorities decide where and when to make safety improvements or changes to speed limits.