The Frankston line is a commuter railway line in the city of Melbourne, Victoria, Australia. Operated by Metro Trains Melbourne, it is the city's third-longest metropolitan railway line, at 42.7 kilometres (26.5 mi). The line runs from Flinders Street station in central Melbourne to Frankston station in the south-east, serving 28 stations via South Yarra, Caulfield, Moorabbin, and Mordialloc. The line continues to Stony Point on the non-electrified Stony Point line. The line operates for approximately 20 hours a day (from approximately 4:00 am to around 11:30 pm) with 24 hour service available on Friday and Saturday nights. During peak hour, headways of up to 5 to 10 minutes are operated with services every 10–20 minutes during off-peak hours. Trains on the Frankston line run with a two three-car formations of Comeng, Siemens Nexas, and X'Trapolis 100 trainsets.

Sections of the Frankston line opened as early as 1881, with the line fully extended to Frankston in 1882. A limited number of stations were first opened, with infill stations progressively opened between 1881 and 2017. The line was built to connect Melbourne with the rural towns of Caulfield, Moorabbin, and Frankston, amongst others. Significant growth has occurred since opening, with a plan to extend the Frankston line along part of the Stony Point line to Baxter.

Since the 2010s, due to the heavily utilised infrastructure of the Frankston line, significant improvements and upgrades have been made. Different packages of works have upgraded the corridor to replace sleepers, upgrading signalling technology, the introduction of new rolling stock, and the removal of all level crossings.

In 1881, the Frankston line began operations by the Victorian Railways on a single tracked line from Caulfield to Mordialloc. Mordialloc station was officially opened on 19 December 1881 by Sir Thomas Bent, who was the Minister of Railways, and later becoming the Premier of Victoria between 1904 and 1909. The first train to arrive at Mordialloc was a special service from Princes Bridge, which collected school children from the Brighton area. Further specials occurred during the day, with proper timetabled services commencing the following day. Six services were provided upon opening and, apart from two services, all were shuttle services operating between Caulfield and Mordialloc.

In August 1882, operations were extended from Mordialloc to Frankston. The section of track from Caulfield to Mordialloc was duplicated in 1888. In 1883 the line between Richmond station and South Yarra was quadrupled to accommodate an increase in train services due to the opening of Frankston and Sandringham lines.

In 1885, a number of level crossing removal works occurred between Flinders Street station and South Yarra due to an increase in freight and passenger operations. These crossings were removed through a combination of lowering and raising the corridor.

In 1910, the remaining track from Mordialloc to Frankston was duplicated. In 1915, the line between South Yarra and Caulfield was quadrupled, as part of level crossing removal works. This section of the line was lowered into a cutting to eliminate numerous level crossings. Power signalling was provided between Richmond and Hawksburn at the same time, then on to Caulfield in 1921.

Electrification of the line to Frankston occurred in three stages during 1922. In March 1922, the section from South Yarra to Glen Huntly station was electrified, with the section to Mordialloc being electrified in June 1922, and the final section to Frankston being completed by August 1922. The electrification of the line allowed for the introduction of Swing Door electric multiple unit trains for the first time.

The introduction of power signalling on the line begun in 1933 with the section from Caulfield to Glen Huntly, with the remainder of the line converted in stages from 1958 to 1986. The current bridge over the Patterson River was provided in 1974, replacing the previous trestle bridge. Triplication of the line from Caulfield to Moorabbin from two to three tracks was announced by Transport Minister Steve Crabb in 1984, at a cost of A$10 million. Construction of the additional track was designed to increase peak hour capacity and to provide express services on the corridor, with time savings of more than 10 minutes from Frankston. Work begun in July that year with a completion by the end of 1985. The introduction of services on the new track was delayed by two years till June 1987. Further plans announced in the 1970s included the extension of the third track to Mordialloc, however, these plans failed to materialise.

In 1981, Frankston line services commenced operations through the City Loop, after previously terminating at Flinders or Spencer Street stations. The commencement of operations involved the service stopping at three new stations—Parliament, Melbourne Central (formally Museum), and Flagstaff. The Loop follows La Trobe and Spring Streets along the northern and eastern edges of the Hoddle Grid. The Loop connects with Melbourne's two busiest stations, Flinders Street and Southern Cross, via the elevated Flinders Street Viaduct.

A 2007, restructure of train ticketing in Melbourne involved the removal of Zone 3, with Zone 3 stations being re-classified to Zone 2. This brought the cost of train fares down, improving system accessibility to the public. All stations between Patterson and Frankston were rezoned to Zone 2.

At the 2010 state election, both the Labor Party and the Liberal Party promised to provide a new Premium station between Highett and Cheltenham, to serve the Westfield Southland shopping centre. The station was projected to cost $13 million, and would have two platforms, an information booth, and shelters with a projected usage of 1,400 passengers daily. The project was scheduled to be completed by 2014, however, no progress was made till after the 2014 state election. The new station opened on 26 November 2017 as Southland station. In 2013, the line, along with the Werribee and Williamstown lines, were upgraded as part of the Bayside Rail Project. The upgrade included station refurbishments, track, signal, and electrical upgrades to allow X'Trapolis trains to operate on these lines.

In 2021, the metropolitan timetable underwent a major rewrite, resulting in all Frankston line trains operating direct between Richmond and Flinders Street before continuing onto the Werribee and Williamstown lines. Under these changes, Frankston services no longer operate via the City Loop, with an additional 45 new services each week. The additional services upgraded frequencies to a train every 5 minutes in peak hour, every 10 minutes throughout the day, and every 20 minutes until midnight.

The Level Crossing Removal Project has announced the removal of all 23 remaining level crossings on the Frankston line, to be completed in stages from 2016 to 2029. Different removal packages have been announced in 2014, 2018, and 2022 to coincide with different state elections and to be delivered in stages up until 2029. All of the various removals have involved the rail under or rail over methods, with some crossing closures also undertaken by the Project. At the conclusion of the project, all level crossings between the city and Frankston station will be full grade operated through a variety of methods.

When the new cross-city rail corridor being built by the Metro Tunnel opens in 2025 there will be a reorganisation of the Melbourne rail network. The Victorian Department of Transport and Planning plans to return the Frankston line to the City Loop, with dedicated use of the Caulfield group tunnel track. This will mean Frankston line trains will no longer through-run with Werribee and Williamstown line trains, and will again stop at City Loop stations Flagstaff, Melbourne Central and Parliament. Werribee and Williamstown services would instead continue onto the Sandringham line.

Stage 4 of the Network Development Plan – Metropolitan Rail proposed that the Craigieburn and Frankston lines be joined via a reconfigured City Loop sometime in the 2030s.

In 2013, as part of Public Transport Victoria's Network Development Plan for metropolitan rail, an extension of the Frankston line to Baxter was earmarked to begin in the "long-term", which would equate to at least 2033. The proposal would link Frankston to Baxter through an electrified dual-line following the Stony Point line. In 2018, the Liberal Party announced a project to extend electrified services to Baxter during the 2018 state election. The project would have included the removal of all crossings between Frankston and Baxter, duplication and electrification works, the reconstruction and redevelopment of the stations at Leawarra and Langwarrin respectively to facilitate electrification.

The Federal Liberals announced $450 million of joint funding for the project promised between the state and federal governments. The incumbent Andrews Labor government argued that the project was not needed, instead prioritising funding to other projects across the state. A business case commissioned by the government was completed in 2019 with no further progress being made.

Again in the lead up to the 2022 state election, the Liberal opposition supported the electrification to Baxter. The incumbent Andrews government made no commitments to the Baxter rail extension, instead continuing construction on level crossing removal works along the Frankston line. The 2022 state election resulted in another Labor victory, with the Andrews government pushing ahead with these works, with the extension to Baxter remaining stagnant ever since.

Services on the Frankston line operates from approximately 4:00 am to around 11:30 daily. In general, during peak hours, train frequency is 10 minutes during the peak period while services during non-peak hours drops to 10–20 minutes throughout the entire route. Rather than running through the City Loop, services continue onto the Werribee (express or via the Altona Loop) or Williamstown lines (with varying frequencies). On Friday nights and weekends, services run 24 hours a day, with 60 minute frequencies available outside of normal operating hours.

Freight operations occur (usually) twice-daily, with Qube Holdings operating services to the Long Island steel mills and the Port of Hastings. Trains to Melbourne run approximately at 4 am and during the mid-afternoon, while trains from Melbourne run approximately at midnight and noon.

Train services on the Frankston line are also subjected to maintenance and renewal works, usually on selected Fridays and Saturdays. Shuttle bus services are provided throughout the duration of works for affected commuters.

Legend — Station Status

• ◼ Premium Station – Station staffed from first to last train
• ◻ Host Station – Usually staffed during morning peak, however this can vary for different stations on the network.

Legend — Stopping Patterns
Services do not operate via the City Loop

• ● – All trains stop
• ◐ – Some services do not stop
• ▲ – Only inbound trains stop
• ▼ – Only outbound trains stop
• | – Trains pass and do not stop

Frankston Services
Station	Zone	Local	Ltd Express	Carrum	Mordialloc	Cheltenham
◼ Southern Cross	1	◐	◐	◐	◐	◐
◼ Flinders Street		●	●	●	▼	●
◼ Richmond		●	●	●	▼	●
◼ South Yarra		●	●	●	▼	●
◻ Hawksburn		●	|	●	▼	●
◻ Toorak		●	|	●	▼	●
◻ Armadale		●	|	●	▼	●
◻ Malvern		●	▲	●	▼	●
◼ Caulfield		●	●	●	▼	●
◻ Glen Huntly		●	|	●	▼	●
◻ Ormond	1/2	●	|	●	▼	●
◻ McKinnon		●	|	●	▼	●
◼ Bentleigh		●	|	●	▼	●
◻ Patterson	2	●	|	●	▼	●
◼ Moorabbin		●	|	●	▼	●
◻ Highett		●	|	●	▼	●
◻ Southland		●	|	●	▼	●
◼ Cheltenham		●	●	●	▼	●
◼ Mentone		●	●	●	▼
◻ Parkdale		●	●	●	▼
◼ Mordialloc		●	●	●	▼
◻ Aspendale		●	●	●
◻ Edithvale		●	●	●
◻ Chelsea		●	●	●
◻ Bonbeach		●	●	●
◼ Carrum		●	●	●
◻ Seaford		●	●
◻ Kananook		●	●
◼ Frankston		●	●

The Frankston line has had a total of 7 operators since its opening in 1881. The majority of operations throughout its history have been government run: from its first service in 1881 until the 1999 privatisation of Melbourne's rail network, four different government operators have run the line. These operators, Victorian Railways, the Metropolitan Transit Authority, the Public Transport Corporation, and Bayside Trains have a combined operational length of 118 years.

Bayside Trains was privatised in August 1999 and later rebranded M>Train. In 2002, M>Train was placed into receivership and the state government regained ownership of the line, with KPMG appointed as receivers to operate M>Train on behalf of the state government. Two years later, rival train operator Connex Melbourne took over the M>Train operations including the Frankston line. Metro Trains Melbourne, the current private operator, then took over the operations in 2009. The private operators have had a combined operational period of 25 years.

Past and present operators of the Frankston line:

Operator	Assumed operations	Ceased operations	Length of operations
Victorian Railways	1881	1983	102 years
Metropolitan Transit Authority	1983	1989	6 years
Public Transport Corporation	1989	1998	9 years
Bayside Trains (government operator)	1998	1999	1 years
M>Train	1999	2004	5 years
Connex Melbourne	2004	2009	5 years
Metro Trains Melbourne	2009	incumbent	15 years (ongoing)

v t e Frankston line
Legend
km Multiple lines via North Melbourne City Loop 1.2 Southern Cross ●●●●●●● 2.5 Flagstaff ●●●● 3.1 Melbourne Central 4.3 Parliament ●● 0.0 Flinders Street ●● 0.1 Princes Bridge (closed) Hurstbridge & Mernda lines to Jolimont City Loop 1.8 Botanic Gardens (dismantled) 2.3 Punt Road (Hoddle Highway) 2.6 Richmond ●●●●●●■ 2.7 Swan Street Alamein, Belgrave, Glen Waverley & Lilydale lines to Burnley 3.4 Cremorne (dismantled) 3.6 Cremorne Bridge CityLink Yarra River 4.2 South Yarra ●■ 4.3 Toorak Road (Burwood Highway) Sandringham line to Sandringham Melbourne Metro Tunnel to Footscray (under construction) 5.4 Hawksburn 5.6 Williams Road 6.7 Toorak 7.3 High Street 7.4 Armadale 8.7 Glenferrie Road 8.9 Malvern ■■■ 9.2 Dandenong Road (Princes Highway) 10.6 Caulfield ●●●●■ Bairnsdale/Traralgon, Cranbourne & Pakenham lines to Dandenong 11.8 Neerim Road (Removing by 2023) 12.2 Glen Huntly ■ 13.0 Rosstown Railway (dismantled) Connection never built 13.8 North Road 13.8 Ormond 14.6 McKinnon 15.2 Bentleigh 15.4 Centre Road 16.2 Patterson 17.1 South Road 17.2 Moorabbin 17.3 Nepean Highway 18.8 Highett 20.2 Southland 21.1 Cheltenham 23.0 Balcombe Road 23.1 Mentone 23.9 Warrigal Road (Removing by 2025) 24.7 Parkdale 25.8 Nepean Highway 26.5 Mordialloc 26.9 Mordialloc Creek 29.1 Aspendale 30.4 Edithvale 30.5 Edithvale Road (State Highway) 32.1 Chelsea 33.4 Bonbeach 34.4 Patterson River 34.9 McLeod Road 34.9 Carrum 36.6 Crystal Sand Siding (dismantled) 36.7 Monolyte Siding (dismantled) 37.3 McCulloch's Siding (dismantled) 37.9 Kelvin's Siding (dismantled) 38.0 Albion Sand Siding dismantled) 38.1 Seaford 40.2 Kananook 41.2 Overton Road (Dandenong Valley Highway) 42.7 Frankston ● Stony Point line to Stony Point km