The Carlingford line runs from Clyde on the main western line to the north western suburb of Carlingford. It is unusual in that is single line, and only sees short four car electric trains, due to the reduced power capacity of the overhead and the length of the platforms.
The former, now abandoned, Sandown line branched off this line at Camellia.
There have been plans to extend this line east to Epping, linking it to the Epping Chatswood Line forming another loop line, and west directly to Parramatta these however have waned with the imminent conversion of the latter to rapid transit standards.
The line is now subject to consideration for conversion to a light rail line between Parramatta and Macquarie Park via Epping or Eastwood - a decision should be made shortly (March 2015).