The Carlingford Branch Line was opened in two sections: Clyde to Camellia was opened on 17 November 1888, and Camellia to Carlingford (then known as Pennant Hills) was opened on 20 April 1896. Telopea Station was added in 1925. Originally the line was privately owned by two companies: the line from Clyde to Rosehill was owned by a Mr John Bennett and the line from Rosehill to Carlingford was owned by the Rosehill Railway Company. The lines were taken over by their bank in 1896, with the Government purchasing the line in 1898 and reopening services on 1 August 1900.
The line from Clyde to Rosehill was electrified on 12 December 1936. The electrification was extended to Carlingford on 9 August 1959. After electrifiction, services were operated by 3 car single deck trains marshalled into Y-Sets, until their final withdrawal in 1993.
In early 2007 the pedestrian at Telopea and Dundas stations were rebuilt. The new automatic crossings provide audible and visual warnings of an approaching train and a short time later close the metal gates.
Over the week of 20 October to 26 October 2007, the section of from Telopea to Carlingford was completely replaced, utilising concrete instead of timber ones. The section from Telopea to Rosehill was similarly upgraded over the fortnight of 22 June to 3 July 2009. The railway remains on timber sleepers from Rosehill to Clyde.
*** Congrats to Pettersen Family and Snoopy1976 for the joint FTF ***