Staying In Your Lane
RCW 46.61.140 — as nearly as practicable entirely within a single lane, and the center lane of three
Two duties. On a roadway divided into two or more clearly marked lanes, a vehicle is driven as nearly as practicable entirely within a single lane, and is not moved from it until the driver has first ascertained that the movement can be made with safety.
The standard the section writes is as nearly as practicable entirely within a single lane, with any move out of the lane waiting until it can be made safely. How courts apply those words to a brief touch of a line is not on this page.
The center lane of three. On a roadway divided into three lanes with two way traffic, a vehicle is not driven in the center lane except when overtaking and passing with the center lane clear for a safe distance, when preparing for a left turn, or where the center lane is allocated to the vehicle's direction by official traffic control devices.
Devices, and the roundabout. Official devices may designate lanes for slow moving or specified traffic, or by direction, or prohibit lane changes on sections of roadway. A commercial motor vehicle may, with due regard for other traffic, deviate from its lane as needed to approach and drive through a circular intersection.
Whether a particular drift over a line was a violation, or a reason for a stop, depends on the facts and on how the courts read the words as nearly as practicable, and is a question for a licensed Washington attorney.
Sources for this section (1)
- RCW 46.61.140 — Driving on roadways laned for traffic
Legal information, not legal advice. Verified as of September 2026. Applying it to a particular situation is the work of a licensed Washington attorney.