From 1929 the company began to acquire bus assets throughout Donegal. Further expansion followed rapidly. It entered profitability in the early 1930s as a result of these ventures. Acquisition of freight operations followed, and this led to a reduction of rail services and eventual closure of lines. The Carndonagh branch was closed in about 1935 and the Burtonport line closing entirely in 1940, with a section temporarily re-opening in 1941 to Gweedore, closing finally in 1947. The Buncrana section of the line lost its passenger service in 1948, with its freight service, and the remaining Letterkenny services all closing on 8 August 1953.