Southern Line (Thailand)

In 1894, the Danish engineer Aage Westenholz (1859-1935), uncle of the writer Karen Blixen, was given a concession to build a route from Bangkok to Phetchaburi. As with other, similar railway construction projects of this time in Thailand, the project failed due to the difficulty of raising sufficient capital for the project. As a result, the Thai state decided in 1898 to build the main links of the country by the state itself and bought back the concession. Other concession requests made by railroad entrepreneurs in the Thai part of the Malay Peninsula were all rejected.

After the Thai state had bought back the West timber concession, the Royal Railway Department (RRD) in the Ministry of Public Works planned a route, under Karl Bethge from the Krupp Company, to Phetchaburi. The construction work began in April 1900.

Because of the length of the route, the construction occurred simultaneously in three sections:

1. from Phetchaburi to the south
2. from the port Songkhla on the east coast
3. from Kantang port on the west coast of the Malay Peninsula.

In contrast to the rest of the Thai railway network, which was built in standard gauge, the Royal State Railways of Siam chose the meter gauge with the intention of facilitating a seamless connection to the metre gauge railways in both Burma and Malaya.

As there was no bridge over the Chao Phraya river, the Southern Railway was isolated from the rest of the network. The route did not start from the Bangkok Hua Lamphong Railway Station, but from its own terminus in Thonburi on the west side of the Chao Phraya river. The station was accessible by ferry from the east side of the Chao Phraya river. Thonburi station's building was designed in the style of brick expressionism by the German architect Karl Döhring, engineer with the Royal State Railways of Siam.

On April 1, 1903, traffic on the first completed section between Thonburi and Phetchaburi was operated with makeshift carriage material as delivery of a significant portion of the rail vehicles was delayed. When these had arrived, the official opening was held on June 19, 1903 by King Chulalongkorn (Rama V.)

More sections followed successively from 1911. The opening dates are as follows:

• 1911: Phetchaburi – Hua Hin in two sections,
• 1913: Kantang – Huai Yot
• 1 January 1914: Kantang – Thung Song Junction
• 1 January 1914: Songkhla–Phatthalung
• 1 January 1914: Hua Hin–Wang Phong
• 1 October 1914: The sections driven by Kantang and Songkhla are merged.
• 1 October 1916: The southern and the northern parts of the line were merged at Chumphon and continuous operation could occur.

On July 1, 1918, trains were able to operate from Thon Buri Railway station to Malaysia via Padang Besar. The initial service was two trains per week and the journey time was 60 hours. An official opening ceremony did not take place because of World War One. Long-distance trips were interrupted for overnight stays with the Royal State Railways of Siam providing hotels at major train stations. In 1922, night traffic and sleeping cars were introduced and the travel time from Bangkok to Penang reduced to just over 30 hours

The Railway was forced to relinquish the meter gauge line, already built under its direction from Bangkok Thonburi to Phetchaburi to the Southern State Railway. This was not only technically reasonable, because it provided a uniform administration for each of the two gauges operated by the state, but also a political balancing act of the Thailand, which until 1917 was neutral in the First World War. The northern RRD worked under the German director Karl Bethgen, the southern under the British Henry Gittens, whose countries of origin were now enemies of the war.

After Thailand's entry into the war on the British and French sides on July 22, 1917, the connection of the Malay and the Thai railway network received high priority. Initially, it was planned to establish the connection via the east coast of Malaysia following route. The construction progress of the track in Malaysia was slow. So the authorities decided to establish a connection with the Malay West Railway. This was put into operation in 1918. The route over the eastern border crossing Sungai Kolok could only go into operation on 1 November 1921.

Construction started in December 1922 of the Rama VI Bridge (Thai: สะพานพระราม 6) over the Chao Phraya River during the reign of Rama VI. Opened on 1 January 1927 it linked the Northern and Eastern rail lines with the Southern railway and allowed Southern Railway trains to operate into Bangkok Hua Lamphong Railway Station.

The original Thon Buri Railway Station was destroyed in the air raids in 1945. After World War II, General Philbul Songkhram had the Thon Buri Station Building rebuilt in the original style.

In 2003, the terminus of the line westward to the previous station Bangkok Noi, was relocated and the vacated railway area was utilised for the extension of Siriraj Hospital. The Bangkok Noi station reverted to the name Thon Buri Railway Station.

In 2015, the Siriraj Phimukhsthan Museum was opened in what was the original Thon Buri Railway Station.

The current Southern Line of Thailand consists of the Su-ngai Kolok Main Line running from Bangkok Hua Lamphong to Su-ngai Kolok District, Narathiwat Province. There are seven branch lines off the main line:

1. Thon Buri Line : short branch line in Bangkok running from Thon Buri Railway Station
2. Suphanburi Line : from Bangkok to Suphanburi . It is also the part of Greater Bangkok Commuter rail .
3. Burma Railway (or Nam Tok Line ): from Ban Pong, Ratchaburi to Sai Yok District , Kanchanaburi Province
4. Khiri Rat Nikhom Line : from Surat Thani to Khiri Rat Nikhom District
5. Kantang Line : from Thung Song District , Nakhon Si Thammarat Province to Kantang District , Trang Province
6. Nakhon Si Thammarat Line : 35.01km branch line from Khao Chum Thong Junction to Nakhon Si Thammarat (km 816.02). This was opened on 1 October 1914
7. Padang Besar Line : from Hat Yai Junction Station to Butterworth, Penang, Malaysia via Padang Besar Railway Station which is where the Keretapi Tanah Melayu (KTM) (Malayan Railways Limited) and State Railway of Thailand services meet

There are two lines that are defunct:

The Southern Line has been the target of terrorist attacks of the South Thailand Insurgency especially between the Hat Yai-Sungai Kolok section. All stations and halts between Hat Yai Junction and Sungai Kolok have been fenced off and gates are opened and closed only during operating hours.

• 
  Hua Hin Railway Station, a beautiful station on the Su-ngai Kolok Main Line
• 
  Charansanitwong Railway Halt on the short Thon Buri Line
• 
  Kra Sae Cave Railway Viaduct on the Burma Railway
• 
  Ban Thung Pho Junction, a station of the Su-ngai Kolok Main Line and Khiri Rat Nikhom Line
• 
  Kantang Railway Station, terminal station of the Kantang Line
• 
  Nakhon Si Thammarat Station, terminal station of the Nakhon Si Thammarat Line

• Bang Sue Junction - Main junction and freight terminal with main Diesel Locomotive Depot and Refueling facility
• Bang Bamru Station- Suburban Station, all trains must stop here. First station after crossing the Rama 6 Bridge from Bang Sue.
• Taling Chan Junction- Junction for Southern Main Line(Bang Sue-Taling Chan Link) and Thonburi Branch.
• Thonburi Station - Former terminus of Southern Line, however some southern trains remain to start the journey here.
• Salaya Station- Suburban Station, for Phutthamonthon District and Mahidol University (Salaya Campus)
• Nakhon Pathom Station - Main southern suburban station. Main Nakhon Pathom station.
• Nong Pladuk Junction - Junction for Namtok Branch Line and Suphan Buri Branch Line.
• Ban Pong Station - Interchange to Kanchanaburi for those who did not travel along Nam Tok branch line
• Ratchaburi Station - Terminal for southern suburban service, also Ratchaburi main station.
• Phetchaburi Station - Phetchaburi main station.
• Hua Hin Station - Provincial Station for Hua Hin in Prachuap Khiri Khan with beautiful architecture, crew changing station.
• Wang Phong Station- One of the stations in Pran Buri. Also for the nearby Thanarat Military Camp. More trains stop here for Pran Buri than Pran Buri Station itself.
• Pran Buri Station- Smaller station for Pran Buri, with a famous Saturday Night Market opposite the station.
• Prachuap Khiri Khan Station - Prachuap Khiri Khan main station.
• Bang Saphan Yai Station - Regional Town Station, however all trains going further south must stop here.
• Chumphon Station - Main Chumphon station, locomotive depot with refueling facility
• Lang Suan Station- Provincial Station in Chumphon. Furthest extent of southern services from Thonburi.
• Ban Thung Pho Junction - Southern Container Yard, for Khiri Rat Nikhom Branch.
• Khiri Rat Nikhom Station - Terminus for the Khiri Rat Nikhom Branch and the railway plan to Phang-Nga and Tanun (Phuket).
• Surat Thani Station - Crew changing station and Surat Thani main station.
• Thung Song Junction - Locomotive Depot, refueling facility and junction for Kantang Branch.
• Trang Station - Trang main station.
• Kantang Station - Terminus of Kantang Branch.
• Khao Chum Thong Junction - Junction for Nakhon Si Thammarat Branch.
• Nakhon Si Thammarat Station - Terminus of Nakhon Si Thammarat Branch. Nakhon Si Thammarat main station.
• Phatthalung Station - Phatthalung main station, crew changing station
• Hat Yai Junction - Main junction for Malaysia and Singapore and Main Line of Southern Line, Locomotive Depot and refueling facility. Main Songkhla Station.
• Padang Besar Station - International KTM station in Malaysia. Trains continue to Butterworth (Penang) and further.
• Pattani Station - formerly Khok Pho station, Pattani main station.
• Yala Station - Main Yala station, crew changing station
• Tanyong Mat Station - for Ra Ngae district and Narathiwat.
• Su-ngai Kolok Station - Terminus of Southern Line. Used to be an international station until the termination of cross border services.