Centred in the Brisbane central business district, the network extends as far as Gympie in the north, Varsity Lakes in the south, Rosewood in the west, and Cleveland in the east to Moreton Bay.

[2] Each line is ascribed a colour and name on all Queensland Rail signage and marketing collateral including timetables, posters and maps.

This was converted to dual 1435/1067 mm gauge and extended in parallel with the duplicated passenger line to Dutton Park in about 1995 under the Keating government's One Nation program.

A start on electrification of the suburban network was approved in 1950 but a change of state government in 1957 saw the scheme abandoned in 1959.

[16] To increase the capacity on a number of lines, the rail network in Brisbane has required some tracks to be duplicated.

In June 2004, Queensland Government announced rail duplication of the Gold Coast line between Ormeau and Coomera stations.

Previously two tracks, the added capacity allows Gold Coast line services to operate with less chance of delays.

Other improvements include lifts and footbridges, to meet the Disability Standards for Accessible Public Transport, and new, modern station buildings.

The line between Ormeau and Coomera stations, 6.7 km (4.2 mi) in length, was duplicated in October 2006, allowing for additional capacity.

[22] Similarly, the 16.6 km (10.3 mi) length between Helensvale and Robina stations was duplicated in July 2008, removing the need for a four-minute layover at Helensvale for Robina services to wait for the Brisbane service due to the single track either side of the station.

Previously four tracks to Corinda then two to Ipswich, the quadruplication allowed for greater capacity, especially with the Springfield railway line branching from Darra station.

[24] From Beerburrum station, 17 km (11 mi) of track to Landsborough is proposed to be similarly duplicated and re-aligned.

[26] Under a BOOT scheme – build, own, operate and transfer – the Queensland Government licensed Airtrain Citylink to build the rail line, to own and operate it, and hand the entire infrastructure over to the Queensland Government after 35 years when the company will then cease to exist.

Further extension of the line including proposed stations at Tallebudgera, Elanora and Tugun is expected to be constructed after the completion of the Cross River Rail project.

[32][33] The Redcliffe Peninsula railway line (previously known as the Moreton Bay Rail link) is a suburban railway line extending 27.5 km (17.1 mi) north-northwest from Brisbane central business district (approximately 40.1 km (24.9 mi) from Central station.

A number of upgrades and extensions are planned or under construction for the rail network in South East Queensland.

Dismissing a City Loop-style scenario similar to Melbourne, citing the relatively small size of the CBD and "technical and operational constraints", Lucas imagined an underground line from Park Road station to Woolloongabba, then across the Brisbane River to connect with the Exhibition railway line, with major new stations at Woolloongabba, Gardens Point/QUT, and in the CBD.

Lucas allocated A$5 million to the study and appointed AECOM and Parsons Brinckerhoff as consultants to "look at options for boosting rail capacity in the city centre, including potential for an underground tunnel".

[37] In 2017, work began on a second rail river crossing for Brisbane as the Merivale Bridge nears capacity.

Suburban and interurban passenger services are operated under the Citytrain brand of Queensland Rail, and are co-ordinated by Translink.

Dual gauge access on the line was promised by the Federal Fraser government in 1983, but it was not until 1997 that the work was carried out, eliminating the break-of-gauge and enabling trains to run direct from the port across the New South Wales border.

One of the largest internal traffic flows is the movement of coal along the Western Line to the Swanbank Power Station and the Port of Brisbane.

[14] Other rail freight terminals have been located at South Brisbane, Park Road, Yeerongpilly, Clapham, and Salisbury.

[47] The South East Queensland rail network structures its fares according to Translink's eight pricing zones.

Suburban trains are occasionally scheduled on interurban lines if other toilet equipped rolling stock is not available.