Washington Revised Code Title 46. Motor Vehicles § 46.04.220. Intersection area

(1) “Intersection area” means the area embraced within the prolongation or connection of the lateral curb lines, or, if none then the lateral boundary lines of the roadways of two or more highways which join one another at, or approximately at, right angles, or the area within which vehicles traveling upon different highways joining at any other angle may come in conflict.

(2) Where a highway includes two roadways thirty feet or more apart, then every crossing of each roadway of such divided highway by an intersecting highway shall be regarded as a separate intersection. In the event such intersecting highway also includes two roadways thirty feet or more apart, then every crossing of two roadways of such highways shall be regarded as a separate intersection.

(3) The junction of an alley with a street or highway shall not constitute an intersection.