Construction of the Coolgardie–Widgiemooltha section was completed in 1934, and opened to traffic progressively between June and September of that year. The constructed length was extended to Pioneer between late-1934 and May 1935, with works then progressing to the Pioneer–Norseman portion. The works at Norseman were by August nearly complete, and by November construction was underway south of Norseman, on the Scaddan–Gibson section. Further construction was undertaken in early 1936 south of Norseman and Gibson, and near Esperance later in the year. The Red Lake to Treslove portion was under construction in 1937, with further work near Esperance, Widglemooltha, and Treslove in 1938.