Legislation designed to crack down on high-risk drivers has been passed by Parliament which will raise the minimum driving age to 16.

Transport Minister Steven Joyce said the legislation was a major step forward in the government's efforts to improve road safety and bring down the road toll.

The driving age change will come into force on August 1 this year. Transitional arrangements will be in place for drivers aged under 16 when the driving age increases. Other provisions will come into force over the next 12 months.

The bill will also allow police to take alcohol readings for research purposes from drivers involved in fatal or serious injury crashes who have a blood alcohol concentration between 50 and 80 milligrams of alcohol per 100 millilitres of blood.

Courts will be given the option to require repeat or serious drink drive offenders to use alcohol interlocks, technology which physically prevents them from driving their cars.

The Land Transport (Road Safety and other Matters) Amendment Bill should be fully implemented by mid-2012 and also includes:

- Providing for the NZ Transport Agency to strengthen the restricted licence test.

- Lowering the youth drink drive limit for drivers under 20 years of age from BAC 0.03 (30 milligrams of alcohol per 100 millilitres of blood or 150 micrograms of alcohol per litre of breath) to BAC zero.

- Repeat drink drive offenders will be subject to a BAC zero limit for 3 years after they receive their licence back.

- Doubling the maximum sentence for dangerous driving causing death from five years to ten years.

A report issued in January showed between 2005 and 2009 642 people were killed in crashes where high-risk drivers were at fault.

Drivers under 30 were the highest contributors to the high-risk group, causing more than 52 per cent of fatal crashes.

Almost half of the high-risk drivers aged 15 to 19 had driven outside the rules of their licence.

Another 14 per cent were also driving over the legal blood-alcohol limit.