California Code
ARTICLE 1 - General Provisions
Section 5216.3.

5216.3. “Main-traveled way” is the traveled way of a highway on which through traffic is carried. In the case of a divided highway, the traveled way of each of the separate roadways for traffic in opposite directions is a main-traveled way. Main-traveled way does not include facilities such as frontage roads, ramps, auxiliary lanes, parking areas, or shoulders.

(Added by renumbering Section 5216.2 by Stats. 2000, Ch. 787, Sec. 2. Effective January 1, 2001.)