PNR South Main Line

The PNR South Main Line (Filipino: Pangunahing Linyang Patimog ng PNR, also known as Southrail and formerly the Main Line South) is one of the two trunk lines that form the Philippine National Railways' network in the island of Luzon, Philippines. It was opened in stages between 1916 and 1938 by the Manila Railroad. Services peaked in the 1940s until the late 1960s, when the system started to decline. Since 1988, it was the only functioning inter-city rail after its counterpart to the north, the North Main Line, was closed. The intercity section of the line in Laguna, Quezon and the Bicol Region was then closed and reopened repeatedly between 2004 and 2014 due to a combination of declining ridership and was closed since then. Currently, only a little more than half of line is operational as the line currently serves two commuter services, namely the Inter-Provincial Commuter from San Pedro, Laguna to Lucena, Quezon and the Bicol Commuter regional rail service between Sipocot and Naga, Camarines Sur and Legazpi, Albay, following the closure of the main line, the PNR Metro Commuter Line between Tutuban station and Laguna.

Since its closure, there has been a planned overhaul of the line. The railway will consist of two standard-gauge lines which will overlap in southern Metro Manila and Laguna. One is the North–South Commuter Railway's South section between Tutuban and Solis stations in north-central Metro Manila to Calamba station in Calamba, Laguna. This route will be electrified with direct current power through overhead lines. The other is the PNR South Long Haul from Sucat station in Muntinlupa to Matnog station in Matnog, Sorsogon. This route will continue to be operated by diesel stock but will run at a maximum speed of 160 km/h (99 mph), over twice higher than the existing narrow-gauge line.

Planning of the Luzon network started in 1875. To the south of Manila would be a line leading to Legazpi, Albay and a branch line leading to Bauan, Batangas.

Some parts of what will become the South Main Line were first constructed in 1903 as part of the Antipolo Line to Rizal under the virtue of Insular Government Act No. 703. The formal construction of a main line to the south of Tutuban station began in 1909 by the virtue of Act No. 1905. By 1909, there was already a line between Tutuban and Naic, Cavite. This was known as the Naic line. Another line was also opened from Calamba, Laguna to Bauan via Batangas City. More lines were constructed into the 1910s including the lines from Nueva Cáceres, Ambos Camarines to Legazpi or Tabaco, Albay as the Legazpi Division, the Pagsanjan branch line and the extension of the Antipolo line to Montalban. Between 1916 and 1919, a new line to Tayabas province was opened and was named the Main Line South and had branch lines covering all provinces in the Southern Tagalog region.

The first intercity service on the new Main Line South was the first Bicol Express, which originally only stopped at Aloneros station in Guinayangan, Quezon between 1916 and 1919. The Main Line South was connected to the Legazpi Division by a fleet of train ferries between Quezon and Camarines Sur. This ferry service became increasingly redundant as the last rail connecting Manila to Bicol was laid on November 17, 1937.

The second Bicol Express, which at that point had been running the full length of the new Main Line South to Legazpi, was inaugurated on January 31, 1938 and became a regular service by May 8 of the same year. On the same day, the golden spike was struck by then-president Manuel L. Quezon at Del Gallego, Camarines Sur. Meanwhile, services on the Naic line and the Tabaco branch were cut and the tracks were dismantled later that year.

Services on the new line peaked for a brief period between 1938 and 1941, and were regarded as one of the most profitable eras for the Manila Railroad. However, most of the rail infrastructure was destroyed by World War II when the United States fought against the Empire of Japan in 1941 and 1944-45. Rehabilitation of the network cost the Manila Railroad ₱20 million (convertible to US$115 million in 2020) and by the late 1950s, most of the network had been restored. More branch lines were cut including the Pagsanjan and Antipolo branches. On August 12, 1956, the Manila Railroad was one of the first in Asia to fully retire its steam locomotive fleet and adopt dieselization.

The Manila Railroad was reorganized into the Philippine National Railways in 1964 by the virtue of Republic Act 4156. The early days of PNR during the 1960s and the early 1970s were also considered by the agency as its best. During this period, there were already proposed extensions of the South Main Line to Sorsogon province enacted by Republic Act 6366. However, increasing maintenance costs, natural disasters and competition from highways prevented the PNR from expanding, and eventually caused the eventual decline of the entire system.