W. Va. Code § 17C-15-41: Vehicles transporting explosives.

Any person operating any vehicle transporting any explosive as a cargo or part of a cargo upon a highway shall at all times comply with the provisions of this section.

(a) Said vehicle shall be marked or placarded on each side and the rear with the word "Explosives" in letters not less than eight inches high, or there shall be displayed on the rear of such vehicle a red flag not less than twenty-four inches square marked with the word "Danger" in white letters six inches high.

(b) Every said vehicle shall be equipped with not less than two fire extinguishers, filled and ready for immediate use, and placed at a convenient point on the vehicle so used.

(c) The state road commissioner is hereby authorized and directed to promulgate such additional regulations governing the transportation of explosives and other dangerous articles by vehicles upon the highways as he shall deem advisable for the protection of the public.