The County Engineer may place and maintain official traffic-control devices to regulate, warn or guide traffic; designate marks, lines and crosswalks; regulate the timing of traffic signals; erect stop signs, yield signs and no-parking signs; establish bus stops, bus stands and taxicab stands; impose weight and size restrictions; and test new or proposed traffic-control devices under actual conditions of traffic, all pursuant to the provisions of RCW 46.90.265, Sections 1, 2, 3, 5, 6, 7, 8, 9, 11, 13, 15, 16, 17, 18, 19, 22 and 23.