21651(a) Whenever a highway has been divided into two or more roadways by means of intermittent barriers or by means of a dividing section of not less than two feet in width, either unpaved or delineated by curbs, double-parallel lines, or other markings on the roadway, it is unlawful to do either of the following: (1) To drive any vehicle over, upon, or across the dividing section.
(2) To make any left, semicircular, or U-turn with the vehicle on the divided highway, except through an opening in the barrier designated and intended by public authorities for the use of vehicles or through a plainly marked opening in the dividing section.
... You can clearly see that the area (particularly in the top left illustration) is clearly 0.9 meters which equals 2.95 feet... That is obviously "not less than two feet wide".