The Pakenham line is a commuter railway line in the city of Melbourne, Victoria, Australia. Operated by Metro Trains Melbourne, it is the city's longest metropolitan railway line at . The line runs from Flinders Street station in central Melbourne to Pakenham station in the south-east, serving 27 stations via the City Loop, South Yarra, Caulfield, Oakleigh, and Dandenong. The line operates for approximately 20 hours a day (from approximately 4:00 am to around midnight) 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 20 minutes during off-peak hours. Trains on the Pakenham line run with a seven-car formation operated by High Capacity Metro Trains. Sections of the Pakenham line opened as early as 1859, with the line fully extended to Pakenham in October 1877. A limited number of stations were first opened, with infill stations progressively opened between 1879 and 2012. The line was built to connect Melbourne with the rural towns of Caulfield, Oakleigh, and Dandenong, amongst others. Significant growth has occurred since opening, with a plan to extend the Pakenham line one stop east to a new station in Pakenham East as part of the Level Crossing Removal Project. This extension is planned to open in 2024. Since the 2010s, due to the heavily utilised infrastructure of the Pakenham line, significant improvements and upgrades have been made. A $15 billion upgrade of the corridor included the replacement of sleepers, the introduction of new signalling technology, the introduction of new rolling stock, the removal of all level crossings, and works associated with the Metro Tunnel project. These projects have improved the quality and safety of the line and will be completed by the opening of the Metro Tunnel in 2025. History 19th century In 1877, the Pakenham line began operations from Oakleigh to Bunyip, as part of the main line to Gippsland. The section from Oakleigh to Flinders Street station was connected at South Yarra in April 1879. In 1877, the Pakenham line began operations from Oakleigh to Bunyip, as part of the single-tracked main line to Gippsland, with an extension of the duplicated section of the line opening in 1881 to Caulfield, Oakleigh in 1883, and Dandenong in 1891. In 1883 the line between Richmond station and South Yarra was quadrupled to accommodate an increase in train services due to