Drivers in Yakima and five other cities in the state will be targeted by a team of national researchers who are measuring the amount of impaired driving on Washington roads starting Friday.

The roadside survey is voluntary and anonymous, but you can make $60 if you take the 20-minute survey and give a sample of your saliva.

Officials from the Washington Traffic Safety Commission say because Washington is one of only two states that have legalized recreational marijuana, the roadside survey will provide an important snapshot of driver drug and alcohol use before the marijuana stores open in the summer.

The researchers also plan to study the processes involved with implementing recreational marijuana regulations.

The researchers will be near intersections or in areas where traffic normally backs up, where they will invite motorists to participate in the survey. Participants will be asked questions about their drinking, drugging and driving behavior and, if they consent, they will give a saliva sample and a blood sample.

Drivers who volunteer for the entire survey are given a $60 stipend.