Blue Line (Bangkok)

The MRT Blue Line (Thai: รถไฟฟ้ามหานคร สายสีน้ำเงิน) or MRT Chaloem Ratchamongkon Line (Thai: รถไฟฟ้ามหานคร สายเฉลิมรัชมงคล) is Bangkok's third rapid transit line, following the Sukhumvit line and Silom line of the BTS Skytrain. It is the first line of the MRT system and is operated by Bangkok Expressway and Metro (BEM). The line has a total length of 48 km (29.83 mi), operating as a semi-circle or spiral route from Lak Song to Tha Phra which also serves as a self-interchange station.
The first stage of the MRT Blue Line, a 20 km (12.43 mi) semi-circle alignment from Hua Lamphong to Bang Sue opened on 3 July 2004, which was then followed by a 1.2 km (0.75 mi) extension to Tao Poon opened on 11 August 2017. The line was extended to the west from Hua Lamphong through new stations in Bangkok Chinatown and Ko Rattanakosin on 29 September 2019. Finally, the line was extended south from Tao Poon to Tha Phra through new stations in Thonburi on 30 March 2020, completing the semi-circle line. Another 7.8 km (4.8 mi), 4 station extension from Lak Song to Phutthamonthon Sai 4 is planned but remains unbuilt.
The MRT Blue line connects major business, residential and cultural areas of Bangkok. In late 2019, the average daily ridership was 400,000. During the third wave of COVID-19 in Bangkok, ridership fell to between 76,000 - 116,000 per weekday during the year 2021.
The MRT Blue Line begins from the upper platform of Tha Phra station. It runs on an elevated viaduct northward along Charan Sanit Wong Road to Bang O station before crossing the Chao Phraya River, entering Bang Pho station and Tao Poon station in Bang Sue District. The line then dives underground to reach Bang Sue. It follows the Kamphaeng Phet, Phahon Yothin and Lat Phrao Roads, then turns south following Ratchadaphisek Road to Queen Sirikit National Convention Centre station. It then turns west following Rama IV Road. It passes Hua Lamphong station in Pathum Wan District, through Chinatown, then under the Chao Phraya River before ascending onto an elevated viaduct to the lower platform of Tha Phra station. The line continues west along Phet Kasem Road to Lak Song station in Bang Khae, situated near Kanchanaphisek Road or Western Outer Ring road. It forms a quasi circle loop around Bangkok.
Officially named Chaloem Ratchamongkhon (Thai สายเฉลิมรัชมงคล) – "Celebration of Royal Auspice" – or informally but commonly called as the "MRT Blue Line", this was the first metro line under the newly formed government agency, the Mass Rapid Transit Authority of Thailand (MRTA). Most civil infrastructure was provided by this government agency and handed over to a private sector on a 25-year concessionaire agreement. The winning bidder was Bangkok Expressway and Metro (BEM). Under this agreement, BEM provides maintenance and engineering equipment, including electrical trains, signalling systems, SCADA, communication, platform screen doors and fully operate the system from Hua Lamphong to Bang Sue. BEM has subcontracted maintenance of the system for 10 years to Siemens and seven-year maintenance contracts to two local maintenance services.
In 1996, the Overseas Economic Cooperation Fund (OECF), later known as the Japan Bank for International Cooperation (JBIC), granted the loans for the project with an official development assistance (ODA) scheme. Construction of the line began on 19 November of that year, when Crown Prince His Royal Highness Crown Prince Maha Vajiralongkorn (later King Vajiralongkorn) came to lay the foundation stone for the construction of the MRT project, which is Thailand's first subway project, with the aim of relieving Bangkok's traffic problems. The first contract was awarded to a joint venture between CH. Karnchang Public Company Limited, Bilfinger-Berger, Kumagai Gumi, and Tokyu Construction Co. for the southern section, while one of the remaining contractors, the northern section, was awarded to ION Joint Venture, which comprises Italian Thai Development, Obayashi Corporation, and Nishimatsu Construction, and the depot was awarded to Siam Nippon Metro Consortium, composed of Hazama Corporation, Maeda Corporation, Mitsui & Co., Kajima, T.S.B. Trading, and Siam Syntech Construction Public Co., Ltd. Tunneling works began on 5 February 1999.
During construction, the consultancy was led by the "Berger-CSC 1 Consortium," comprising the following consulting firms: Louis Berger and many more, as well as a joint venture of Mott Macdonald and De Leuw Cather.
The project suffered multiple delays not only because of the 1997 economic crisis, but also due to challenging civil engineering works of constructing massive underground structures deep in the water-logged soil upon which the city is built. The MRT Blue Line opened for a limited public trial period of several weeks starting on 13 April 2004. On 3 July 2004, the line was officially opened at 19:19 local time by HM King Bhumibol and Queen Sirikit who were accompanied by other members of the royal family. Within 30 minutes of its opening, sightseers filled the system to its maximum capacity, but after the initial rush ridership settled down to around 180,000 riders daily—considerably lower than projections of over 400,000, despite fares being slashed in half from 12 to 38 baht to 10-15 baht per trip. It was scheduled to be opened in 2003, in time for the same year's APEC summit, and later pushed back again to April and then August of the following year. However, no problems were encountered during the test run; the official opening was brought forward.
During the early years, it was named the subway as an alternate name.
As part of the rapid transit master plan the original MRT Blue Line section was planned to be extended from Hua Lamphong to Lak Song, and from Bang Sue to Tha Phra, forming a circle open-loop route. The contract for the first part of extension to Tao Poon was signed on 26 August 2009 as part of MRT Purple Line contract as it provided interchange to the MRT Purple Line. The 1.2 km (0.75 mi) Bang Sue to Tao Poon extension opened on 11 August 2017. This added the first elevated station, Tao Poon, to the Blue line.
The major extension of the MRT Blue Line was the 27 km (16.8 mi) extension west to Lak Song and from Tao Poon to Tha Phra with 19 stations consisting of four underground and 15 elevated stations. Contracts for civil work were divided into five contracts. Successful bids were announced in late 2010. On 17 February 2011, the five contracts were signed.
Construction commenced in mid-2011 for a scheduled 2016 opening but this was subsequently delayed to 2019–2020. In August, 2017, BEM awarded the automatic fare collection ticket for the extension to Thales which to install its TransCity system. The contract also includes ongoing training and future support. In September 2017, BEM announced that Siemens and ST Electronics Thailand were awarded the contract (Contract 5) to supply, install and maintain the E&S systems, install station platform screen doors and fit out the depot. Siemens also won the contract to supply 35 sets of rolling stock.
In 2017, the cabinet approved the amendment of the Blue line concession with BEM, and the new agreement was signed on 31 March 2017. Under the new agreement, BEM will operate the new extensions from Hua Lamphong to Lak Song and Bang Sue to Tha Phra. The concession period was extended from 2029 to 2050.
The extension was opened in stages. The Hua Lamphong - Lak Song extension was opened for trial service on 29 July with full commercial services commencing 29 September 2019.
The Tao Poon - Tha Phra extension opened for limited trial services from 29 November 2019 with full commercial services commencing on 30 March 2020.
Since 2011, there were requests from residents to extend the line farther from Lak Song west to the Phutthamonthon area. The MRTA indicated a willingness to undertake this extension. In July 2014, the MRTA submitted a request for 84 million baht to complete a route survey for a 7.8 km (4.8 mi), 4 station extension from Lak Song to Phutthamonthon Sai 4. In late March 2017, the Transport Ministry stated that this 7.8 km (4.8 mi) extension would be submitted to Cabinet for approval in April 2017 with construction expected to commence in the 4th quarter of 2017. However, the tender was subsequently delayed until late 2019 due to other projects. In late 2019, the project was put on hold due to government budget constraints. In August 2021, the MRTA confirmed that the extension was not a priority especially given delays with the tenders for the MRT Orange and MRT Purple line extensions.
The MRT Blue line is served by 54 three-car trains of which, 19 are first generation Siemens Modular Metro sets and 35 sets are second generation. The trains are powered by 750 V DC via third rail system, are air-conditioned and capable of traveling at up to 80 km/h (50 mph).
Nineteen three-car Siemens Modular Metro were ordered for the initial part of the line. The trains entered service on 3 July 2004. In 2017, BEM starts removing some seats from the train to increase interior space to cope with rising number of passengers. In 2019, the BEM stated that it is interested in refurbishing the first generation trains. Including the CCTV cameras, and new dynamic route map replacing the traditional ones.
In 2000, Alstom won a contract to supply 21x3 car Metropolis train sets, and this design would have been similar to C751A used for Singapore's North East MRT line if it had been built. The trains were provided by a consortium called Nippon-Euro Subway Consortium, which also includes Mitsubishi Electric. Mitsubishi Corporation, another consortium member, had also planned to undertake it. However, the negotiations with the French firm have failed. The bidding for rolling stock was conducted again, and bidders include Bombardier Transportation (later acquired by Alstom in 2021) and Siemens, both from Canada and Germany. On 3 January 2002, Siemens won the contract for a cost of $385 million.
* Car 1016 and 1028 were swapped after the train collision in 2005.
In 2017, BEM ordered 35 three-car as part of the line extension program. Under the contract, Siemens were to supply 35 trains and provide maintenance for ten years with a price tag of 20 billion baht. The fleet was built at the Siemens plant in Vienna and tested in Germany. The first train arrived in 2019 with all trains delivered by early 2020.
On 18 July 2024, Mr. Phongsarit Tantisuvanitchkul, executive chairman of BEM revealed that the company will order an additional 21 train sets, each comprising three cars, for the MRT Blue line to meliorate congestion during peak hour. The turnkey contract was announced on 18 December 2024. A consortium consisting of Siemens and Bozankaya won a contract from Ch. Karnchang. The contract includes the supply of 21 Siemens three-car trains, with the design same as the EMU-BLE fleet that is currently used on the project. These trains will be manufactured at the Bozankaya Factory in Ankara, Turkey. Siemens and ST Electronics will supply the bogies, traction, braking, and auxiliary systems, and will be responsible for project management, development, construction, and commissioning. Siemens will also provide service and maintenance for 15 years, from 2024 to 2039.
The MRT Blue Line operates from 05:30 to 24:00 on weekdays and from 06:00 to 24:00 on weekends and public holidays. During the weekday morning rush hour, there are two service patterns:
At opening in 2004, initial ridership was 180,000 per day—considerably lower than the projections of over 400,000. By 2016, the average daily ridership was 273,637. By September 2017, BEM stated that average daily ridership had increased to 360,000 after the opening of the extension to Tao Poon.
After the opening of the extension to Lak Song on 29 September 2019, average daily ridership increased to 400,000. The MRT Blue line was expected to grow to a daily ridership of 800,000 once the Lak Song and Tha Phra extensions opened. However, the impact of the COVID-19 pandemic by late 2020 had resulted in a dramatic reduction of ridership down to an average of 360,000 per weekday reverting to September 2017 levels. By August 2021, during a COVID-19 3rd wave in Bangkok ridership plummeted to only 76,000 per weekday. In 2023 an average of 376,000 passengers rode the blue line.
From 25 January to 31 January 2025, Prime Minister Paetongtarn Shinawatra has implemented a policy of free public transportation in Bangkok for one week. This measure aims to address the worsening air pollution caused by surging dust levels across all districts of the capital.
On 17 January 2005, just after 09:15, an empty train returning to the depot collided with a peak-hour train filled with passengers at the Thailand Cultural Centre station. Around 100-262 people, depending on the news source, were injured. Most of whom sustained only minor injuries, and the entire Metro network was shut down for two weeks. On 31 January 2005, then prime minister Thaksin Shinawatra rode the metro to increase public confidence in the system.
After initial investigations, it was found that the empty train had run into problems shortly before the accident, grinding to a halt on a curve leading to the depot. The driver applied its brake and was waiting to be towed to the depot close to Thailand Cultural Centre station. A rescue train was attempting to connect to the stalled train when the driver was told to release the brake while coupling had not yet been successful. It was then that the empty train began to roll backwards at a speed of ten meters per second, before smashing into the other train, which was carrying passengers. Therefore, it was believed that the incident was caused by negligence due to insufficient training of operation staff. This accident also resulted in two damaged trains with heavily damaged areas limited to the two leading cars. The colliding speed was suspected to be about 60 km/h due to the appearance of damaged areas. However, one train, which was rebuilt from the repair of the minor-damaged cars, was already fitted for operation at the end of 2006 and the remaining one was still under heavy repair until mid of 2007; it was released into service in October 2007. The cost resulting from the accident might be a much higher figure than BEM quoted, and it was expected to be at least 400 million baht, which was totally insured by a local insurance company.
The line resumed full operations on 1 February 2005. Passenger numbers soon rose back to pre-crash levels, partly due to a temporary promotional fare scheme which allowed passengers to travel any distance on the MRT for only ten baht.