The line's low frequency and low level of patronage led to various inquiries and studies into its future. A major problem was the level crossing over
Parramatta Road, which held up traffic when trains travelled across it. Proposals included tunnel links to Clyde or Granville stations, or replacing the line altogether with a more frequent
light rail or
busway service. The
New South Wales Government originally planned for the Carlingford line to be part of Stage 2 of the
Parramatta Rail Link. That plan would have incorporated the majority of the line, with the section between Carlingford and
Camellia duplicated.
Telopea,
Dundas, and
Rydalmere stations would also have been duplicated and upgraded to allow eight car trains. Camellia station would have been demolished, and Rosehill station closed and replaced by a new underground station with a preliminary name of 'Rosehill/Camellia'. Carlingford station would also have been replaced by an underground station. Various proposals were put forward, including a three-way underground junction near Carlingford, linking the station to the proposed
North West Rail Link, as well as the line to
Chatswood. In 2003, the
Minister for Transport,
Michael Costa announced that only Stage 1 of the line, from Chatswood to
Epping, would be built, but the Carlingford line section was indefinitely postponed. Under the
Rail Clearways Project, announced in 2004, the line was to have had a crossing loop at Rydalmere, thus allowing an increase in train frequency to half-hourly throughout the day. However, that part of the Clearways Project was cancelled in November 2008. In August 2010, the
federal government promised $2.6 billion towards the project, which, along with funding from the New South Wales Government, would have allowed the line to be extended from Epping to
Parramatta via the Carlingford line. Work was to commence in 2011, with a projected 2017 finish. Following a change of government at the
2011 state election, the project was shelved. A large amount of land lies behind Carlingford station, for future extensions of the line.
Parramatta Light Rail In 2013,
Parramatta City Council published a feasibility study into a Western Sydney Light Rail network. The study proposed the construction of a light rail line from Parramatta to the
Macquarie Centre, running parallel to the Carlingford line between Camelia and Dundas. The report noted that while the future of the railway line was a matter for the state government, conversion of the line to light rail would reduce the cost of the light rail's construction significantly. {{mapbox raw data|text=Map of the line showing the section to be converted to light rail in grey and the section to close in red.|data= [ { "type": "ExternalData", "service": "page", "title": "T6 Carlingford Line.map" }, { "type": "ExternalData", "service": "page", "title": "Carlingford line conversion to light rail - shaded.map" }, { "type": "ExternalData", "service": "page", "title": "Carlingford line closed - shaded.map" } ] }} In December 2015, the NSW government announced the Camellia to Carlingford section of the line would be converted to light rail, forming a branch of the
Parramatta Light Rail network. That would replace the connection to the Sydney Trains network at Clyde with a link to
Parramatta and
Westmead. As a consequence, the Carlingford line north of Parramatta Road was closed on 5 January 2020 to allow conversion works to take place. Much of the remaining section closed permanently. That included Rosehill station, which is not on the light rail route. The short section between Clyde and the Parramatta Road level crossing will remain open to allow access to Sydney Trains' track inspection depot. The Sandown line was formally closed in July 2019. A
replacement bus service, the route 535, was introduced from Parramatta to Carlingford, and is operated by
Hillsbus. The level crossing across Parramatta Road was removed in late January 2020. ==Services==