The government aims to test just over 3.3 million drivers a year in its plan to increase roadside tests for drink and drug-impaired drivers.

Transport Minister Simeon Brown is launching a $1.3 billion Road Policing Investment Programme which will run for the next three years.

He said 65 percent of breath tests will be done at high or extreme alcohol risk times.

The scheme will also have a target of carrying out 50,000 drug tests per year.

Brown said another priority will be speeding on open roads and at high-risk locations.

"This plan has a clear focus on outcomes and has clear targets to ensure police are focused on the most high-risk times, behaviours, and locations.