A complaint from a Prince George resident won't stop the B.C. Superintendent of Motor Vehicles from continuing to conduct roadside surveys to determine the prevalence of drinking and driving in the province.

In a letter to The Citizen, a local motorist called the survey harassment and a violation of rights because the canvasser not only asked a series of questions but also asked the driver to blow into a breathalyzer and to provide a swab of saliva.

The motorist said requests were made after being directed into a parking lot on 15th Avenue by a police officer late one night in mid-June.

But Steve Martin, the province's Superintendent of Motor Vehicles, said Monday that interviewers make it "very clear" that complying with the requests is strictly voluntary and no personal information is collected.

"And then, if the driver agrees then the interview with the driver begins," Martin said.

Since 1995, the survey has been conducted every second year in communities across B.C. for about two weeks each time and provides important information about the prevalence of impaired driving - both alcohol and drug-related, said Martin.

"It's fairly common," he said. "It's a very well-established, standardized methodology that's used throughout North America."

Relying exclusively on fatality and enforcement statistics is not good enough, he added, because they don't provide the level of detail the department is seeking, notably the degree of impairment among drivers surveyed, from zero to over .08.

If a driver is found to be over the legal limit, they're given a taxi ride home.

"There's no consequence to the driver so we actually get very high participation rates," Martin said.

Fatalities have declined 44 per cent since September 2010 when police began issuing immediate roadside suspensions for anyone with a blood-alcohol level .05 or over, Martin noted.

"But this [survey] will actually give us an indication in terms of to what extent are we actually changing the behaviour of drivers," Martin said.

Justice Minister Shirley Bond has asked Martin to ensure that the proper process was followed and that drivers are notified each time that the roadside survey is voluntary, a ministry spokesperson said Monday.