which did not resume until 1948. Compared to the heyday of the Gäubahn at the end of the 1930s, the service schedule was severely reduced, and did not reach the same level as before the war until the end of the 1950s. The service to and from Berlin, for which the line had been expanded in the time between the wars, was not resumed by the Deutsche Bundesbahn, and the traffic corridor Berlin–Erfurt–Würzburg–Stuttgart–Zürich had lost its significance due to the separation of East Germany and West Germany. Starting in the 1950s, the Bundesbahn extended some of the express trains between Zurich and Stuttgart to Hamburg. Also, express service was reinstated between Stuttgart and Italy, largely due to the influx of guest workers from Italy into Baden-Württemberg at the end of the decade. These trains primarily saw the use of the Prussian P 10 and the Prussian P 8. Between 1958 and the middle of the 1970s, diesel locomotives of the class DB Class V 100 and DB Class V 200 replaced the steam locomotives on the Gäubahn, with the DB Class V 200.1 being used for freight service. The Bundesbahn then electrified the section between Stuttgart and Böblingen in 1963, with the goal of reducing travel time in local service trains in the Stuttgart area. The section Böblingen–Horb was converted to electric operation in 1974, and electrification of the rest of the Gäubahn to Singen was completed in 1977, which meant that primarily electric locomotives were used on the railway after 1977. Also in 1977, the Bundesbahn decided to close numerous stations and halts to enable express-like travel, with higher speeds, even in local service trains. After the section between Böblingen und Stuttgart was electrified in 1963, initially it was locomotives of the DRG class E 17, DB Class 141, DRG Class E 44, and DRB Class ET 55, which saw service. These were then replaced with DRG Class ET 25, DB Class ET 27, and DRG Class ET 65 by 1969. After 1974, and the electrification of the section Böblingen–Horb, the Bundesbahn used the DB Class E 10 for regional service on the northern Gäubahn-section, and used the same locomotive for express service after 1977. For freight service, the Bundesbahn initially relied on the DB Class E 50 and DRG Class E 93, switching to the DB Class 151 in the 1980s, then the DB Class E 40 starting