WAC 296-865-30005. Truck operation

(1) You must make sure truck drivers operate equipment at a safe speed at all times for roadway conditions. (2) You must make sure truck drivers either: (a) Sound their horn before starting to back and intermittently during the entire backing operation; or (b) Have a working automatic reverse signal alarm that is audible: (i) Above the surrounding noise level; and (ii) No less than fifteen feet from the rear of the vehicle. (3) You must make sure, during the backing of trucks where vision is obstructed, a signal person is stationed at a point giving a clear view of the rear of the truck and the operator of the truck at all times.