T8 Airport and South line

The Airport & South Line (commonly called the East Hills Line, after the physical rail line it primarily runs on) is a suburban commuter rail service in Sydney, Australia. It connects the Sydney central business district with the southwestern suburbs via Sydney Airport. The line is part of the Sydney Trains network. The line began operating on 26 November 2017, when the T2 Airport, Inner West & South Line was split in two. Sydney Trains' predecessor CityRail operated the Airport & East Hills line over an identical route between 2000 and 2013.

The line is marked with the sign on network maps and at stations.

History
The main impetus for the construction of the East Hills line was from the real estate industry, which wanted to develop the area where the line was proposed. However construction of the line was delayed, and it became an unemployment relief project during the course of its construction due to the onset of the Great Depression. The Public Works Committee recommended the line to State Parliament in August, 1924, expecting a small operating profit and opening up good building land. The debate on the Bill to construct the line took only 15 minutes after it was introduced at 5.12am on 17 December 1924, and the Governors assent given on 23 December, but no funds were provided. Premier Jack Lang performed the "Turning of the First Sod" ceremony at Padstow on 3 September 1927.

The first section to open was between Tempe and East Hills in 1931. The line was electric and double track between Tempe and Kingsgrove, but unelectrified and single track (apart from a passing loop at Herne Bay, now renamed Riverwood). The electrification was extended to East Hills on 17 December 1939. Over time, the line was upgraded to meet demand, with duplication extended to Riverwood in 1948 and a passing loop opened at Revesby in 1956.

The next extension was from East Hills to meet the Main Southern line at Glenfield, with only one intermediate station at Holsworthy. This was opened in December 1987.

The Airport Link (also known as Airport Line or New Southern Railway) was the next change to the line, opening in 2000. The new link connected a new station at Wolli Creek (near Tempe) to Central station via the Airport. The link is fully underground and double track. It was constructed by tunnel boring machine. As part of this change, the line between Kingsgrove and Wolli Creek was quadruplicated, and the platform configuration at Central was changed.

The Airport line stations (except Wolli Creek) are operated by a private company, the Airport Link Company, as part of a public private partnership (PPP). Under the deal, the private company would cover the costs of building four of the stations. In return, they would operate those stations for 30 years and have the right to impose a surcharge on fares for their use. This didn't work very well due to low patronage and the company went into receivership. However the stations were bought by Westpac and starting in 2006, patronage began to grow and significant profits have been made in recent years.

Patronage continued to grow and more upgrades were constructed, including increasing to four platforms at Revesby in 2009 and extending the quadruplication to Revesby in 2013.

Description
The line is double track in the east. It runs in a double track machine bored tunnel between Central and Wolli Creek. The official name of this line is the New Southern Railway. The peak hour only services running via Sydenham use the Illawara Local ground level tracks, which are shared with the T3 Bankstown Line.

After Wolli Creek, both double track lines run alongside each other but do not merge, forming a four track corridor that is called the East Hills Line. The outer pair are the main (express) line, while the inner pair are the local line. High speed crossovers are located before Turrella to allow services from the Airport to join the express tracks. There are also similar crossovers at Beverly Hills (the former end of quadruplication). The quadruplication now ends after Revesby station.

The line continues as double track to Glenfield, crossing the Georges River twice and passing a disused siding into the military reserve. At Glenfield, there is a grade separated junction with the Main South line, which the T8 service continues on until Macarthur.

Terminating facilities are located at: The line is electrified at 1500V DC and controlled via double colour light signalling (mainly from Sydenham Control Centre). It has fairly high speed limits, with express services hitting their service limit of 115km/h at many locations (e.g. Holsworthy-Glenfield).
 * Central (crossover)
 * Turrella (crossover on local line)
 * Kingsgrove (turnback without platform on local line)
 * Revesby (crossovers on local line)
 * East Hills (turnback platform with crossovers)
 * Campbelltown (turnback platform with crossovers)
 * Macarthur (turnback platform with crossovers)

Historical
Trains on the line originally ran shuttle services. Electric trains shuttled between Kingsgrove and Tempe, while CPH railmotors ran the unelectrified section between Kingsgrove and East Hills. Peak hour through services to the City operated, with electric trains between St James and Kingsgrove, and steam trains between Central and East Hills. At other times, passengers would have to change at Kingsgrove and again at Tempe onto an Illawara service.

This changed in 1937, when all electric trains were extended to run through to St James. They were also extended the other way to East Hills when the electrification opened in 1939. With the opening of the full City Circle in 1956, trains no longer terminated at St James and instead looped back round to Central via Circular Quay.

The next change was the extension to Glenfield in 1987. Initially, trains only used the extension during peak hours, with a few East Hills services extending to Campbelltown. The extension was brought into regular use in 1988, with 2tph (trains per hour) to Campbelltown, running express, and 4tph to East Hills, stopping all stations. The Campbelltown trains were soon extended one stop further to Macarthur.

With the opening of the Airport Link in 2000, most services were diverted to run via the Airport instead of Tempe. Peak hour express trains continued to run via Tempe. With the opening of the fourth platform at Revesby in 2009, all stations services were cut back to Revesby. The quadruplication over the years has also allowed for express trains to run at higher frequencies and skip more stops.

The state's public transport authorities were reorganised around 2013. As part of these changes, the line was renamed. It had run before as the East Hills Line, then the Airport & East Hills Line when the Airport Link opened. It was finally renamed to the T2 Inner West, South & Airport Lines, which was a grouping of several lines that had existed before.

The 2017 timetable saw the 2013 branding changes partially wound back, with the Airport & East Hills separated from the T2 into its own line. It was given the number T8 and the colour green (albeit a slightly different shade to its former colour).

Current
All services originate from the City Circle. Inbound services use the inner circle while outbound services use the outer circle. (It is not possible for this rule to be broken due to the arrangement of the flying junctions at Central)

There are generally two stopping patterns on this line during the off-peak, with both running at 4tph (trains per hour). Stations between Wolli Creek and Revesby are primarily serviced by the inner Local tracks while stations past Revesby are serviced by the outer Express tracks between Wolli Creek and Revesby. An extra express pattern runs via Sydenham during the peak, with a total of 12tph: Late night services run at 4tph, stopping all stations to Macarthur.
 * Local: All stations to Revesby via Airport
 * Express: All stations to Wolli Creek via Airport, then Revesby, all stations to Macarthur
 * Local (as above)
 * Express: All stations to Wolli Creek via Airport, Riverwood, Padstow, Holsworthy, all stations to Macarthur
 * Express: Central, Redfern, Sydenham, Revesby, all to Campbelltown (except Macquarie Fields)

Trackwork services
When there is trackwork on other lines, trains are occasionally diverted to run express to Kingsgrove via Sydenham to terminate.

When there is trackwork on one track only in the City Circle, due to the limitations discussed above, the Airport line cannot switch to the other track. One solution is to terminate at Central Platform 23, using a crossover just inside the Airport Tunnel. However, this solution is now unfavourable as it creates a long single track section at the end, reducing capacity to less than the 8tph required. The other solution is now to divert services in one direction via Sydenham, which allows them to access the other City Circle track. However, this means that Airport passengers no longer have a direct service from the City, instead having to change at Wolli Creek.

In events where the T2 Leppington Line is closed between Granville/Fairfield and Cabramatta/Glenfield for trackwork, services to and from Leppington will also divert via the East Hills Line. If the East Hills Line is closed, services to Macarthur divert via Granville (much like some previously-operated services on the South Line). Additional express services to Campbelltown (diverting via Regents Park) may also run under some circumstances.