Special "turnout" areas marked on a two-lane road

Special "turnout" areas are sometimes marked on two-lane roads. Drive into these areas to allow cars behind you to pass. If you are driving slowly on a two-lane highway or road where passing is unsafe, and five or more vehicles are following you, you must drive into a turnout area to let the vehicles pass. [Turnout Areas and Lanes; Lane Controls; California Driver Handbook]