Section 77-9-231 shall not apply:
(a) to railroads whose principal business is hauling logs;(b) to locomotive engines running for coal or water, doubling hills, returning from trains when broken into, or going to or returning from trains in the yard limits of terminal stations;(c) to engines engaged in regular switching service in yards or road engines switching at intermediate stations; or(d) to any locomotive engines in cases of washouts, wrecks, or when going to the assistance of engines so disabled as to block the main track of a railroad.Codes, Hemingway's 1917, § 7696; 1930, § 6122; 1942, § 7774; Laws, 1908, ch. 95.