deutsche reichsbahn reduced services on the black forest line. in 1939, it operated only nine trains directly between stuttgart and calw on weekdays. most trains from stuttgart ended in leonberg or renningen. nevertheless, the reichsbahn electrified the black forest railway on 18 december 1939 to weil der stadt. this gave the town, which still had a population of only 2,200, a connection to stuttgart's suburban services. the locomotives used to haul through trains from stuttgart to calw and vice versa were changed in weil der stadt.