SDCL § 31-8-5: Design--Separate roadways, markers.

The highway authorities of the state, counties, and municipalities may design any controlled-access facility and regulate, restrict, or prohibit access as to best serve the traffic for which the facility is intended. In this connection the highway authorities may divide and separate any controlled-access facility into separate roadways by the construction of raised curbings, central dividing sections, or other physical separations, or by designating separate roadways by signs, markers, stripes, and the proper lane for traffic by appropriate signs, markers, stripes, and other devices.