Washington Revised Code Title 46. Motor Vehicles § 46.37.260. Alternate road lighting equipment

Any motor vehicle may be operated under the conditions specified in RCW 46.37.020 when equipped with two lighted lamps upon the front thereof capable of revealing persons and objects one hundred feet ahead in lieu of lamps required in RCW 46.37.220 or 46.37.240: PROVIDED, HOWEVER, That at no time shall it be operated at a speed in excess of twenty miles per hour.