The county legislative authority shall erect and maintain upon the county roads such suitable and proper signs, signals, signboards, and guideposts and appropriate stop, caution, warning, restrictive, and directional signs and markings as it deems necessary or as may be required by law. This includes informational signs to address jumping from bridges as authorized in RCW
47.36.410. All such markings shall be in accordance with the uniform state standard of color, design, erection, and location adopted and designed by the Washington state department of transportation. In respect to existing and future railroad grade crossings over county roads the legislative authority shall install and maintain standard, nonmechanical railroad approach warning signs on both sides of the railroad upon the approaches of the county road. All such signs shall be located a sufficient distance from the crossing to give adequate warning to persons traveling on county roads.