been built in the late 17th century, and operations started on 12 September 1874. As early as 25 November 1875, the line was extended to Zweibrücken and connected to the link to the Palatine Ludwig Railway. Conceptually, it was a direct continuation of the Germersheim–Landau railway and the official chainage (distance markings) run in sequence over both routes. At the same time, a branch line was opened from Biebermühle station, which is located at the confluence of the Rodalb with the Schwarzenbach, to Pirmasens. In addition, the original Zweibrücken station was not in an appropriate location for a through station and it had to be so moved to its present location. Although the line was initially built as a single track, its track base, engineering structures and crossings were designed to be duplicated. Development for the main east-west link (1875–1945) After the Bruhrain Railway (Bruhrainbahn) between Bruchsal and Rheinsheim had been extended to Germersheim in May 1877, the now continuous connection became one of the major freight routes in Germany, carrying mainly coal and iron from the Saar region to the industrial centres of the upper Rhine and southern Germany. In contrast, passenger traffic played a minor role in the first few years. But this changed in the late 1880s, because now in addition to local trains, national and even international long-distance trains used the line. From 1890, the Queichtalbahn included long-distance trains on the Munich–Stuttgart–Bruchsal–Germersheim–Landau–Biebermühle (now Pirmasens Nord)–Zweibrücken–Rohrbach–St. Ingbert–Saarbrücken route. This high traffic density made it necessary to increase the capacity of the line, so that was the line from Landau to Bierbach was continuously duplicated from 1887. The existing Hasseler Tunnel, which was opened in 1867 between Hassel and St. Ingbert, had over the years developed more and more structural defects, so that it could be operated at low speed for safety reasons. It was also quite small, with a width of 3.08 metres and a clear height of 4.44 metres. Above all, the military criticised the condition of the tunnel, since it was a bottleneck and thus was not sufficient to ensure, if necessary, the rapid transport of troops and ordnance to France. For this reason, an approximately 2.5 kilometre-long deviation was built between Hassel and St. Ingbert and taken into operation in September 1895, which also made to relocation of Hassel station necessary. The direct connection from Hassel to St. Ingbert was closed and dismantled, and