The line was hampered by the rugged terrain and a change of
gauge at
Wallangarra for traffic to Queensland. The line was superseded as the principal route to
Brisbane by the completion of the
North Coast Line in 1930. Despite being bypassed, the line remained busy for many years afterwards, with the line instead becoming the major freight link to the wheat and wool regions of northern and north-west New South Wales. In 1988, the newly elected state government of
Nick Greiner commissioned a report into the
State Rail Authority by
Booz Allen Hamilton. As a result, the line between Tenterfield and Wallangarra was closed. The last train to operate north of Tenterfield was an
Australian Railway Historical Society charter on 15 January 1988 hauled by diesel locomotive
4487. The last train to operate north of Glen Innes was hauled by steam locomotive
3001 on 22 October 1989 after which the line was formally suspended from operations. Following the
Northern Tablelands Express being truncated in February 1990, the line north of Tamworth saw little use until the
Xplorer service was introduced to Armidale in October 1993. The line to Glen Innes was still open in July 1992 when diesel locomotive
4499 operated a crew training service. There have been attempts to revive freight or tourist traffic to as far as
Glen Innes, although these plans have not yet succeeded. A section of the line between
Waratah and
Maitland is
quadruple track, with one pair being used exclusively for coal trains within the
Hunter Valley coal trains and the other pair being used by passenger trains and general freight. The coal tracks from Port Waratah join the line on the eastern side of the other tracks at Scholey Street Junction and pass underneath the other tracks at Hanbury Dive just west of Maud Street, continuing to Maitland on the western side of the other tracks. In November 1989, a fourth track was added between
Eastwood and
West Ryde. In the mid-1990s a loop was constructed at
Cowan. The
Sandgate Flyover was constructed in 2006 to allow the two tracks to rise and pass over the coal tracks that branch off to
Kooragang Island in order to eliminate a capacity restriction caused by the long coal trains crossing the other tracks at grade. Because of the location of the overpass relative to the branch to Kooragang Island, a short section of the line has six parallel tracks. The bridge carrying Sandgate Road over the lines had to modified to allow for the additional lines.
Sandgate station is flanked by a pair of coal tracks on each side. As part of the
Rail Clearways Program, in August 2006 an additional platform was opened at
Berowra, and in March 2009 an additional platform and passing loop was opened at
Hornsby. In 2011, the
Northern Sydney Freight Corridor project commenced to improve access for freight trains. This has seen the completion of a loop at
Hexham in June 2012, two loops between
Gosford and
Narara in February 2015, plus an underpass and loop between
North Strathfield and
Rhodes in June 2015. A third track between
Epping and
Thornleigh was completed in June 2016. == Engineering heritage award ==