The MRT Purple Line () or The M.R.T. Chalong Ratchadham Line () is Bangkok's fifth rapid transit line, following the Sukhumvit Line, Silom Line, Blue Line, and Airport Rail Link. The line is long, serving the north-western area of Bangkok running from Tao Poon to Khlong Bang Phai in Nonthaburi Province.
The Northern section of the line opened on 6 August 2016, with travel between Khlong Bang Phai and Tao Poon. It is the second line of MRT system and is operated by BEM under a concession contract. Daily ridership is 70,000.https://www.khaosod.co.th/economics/news_2933591. Khaosod ,30 September 2019
A , 17 station Southern extension of the line between Tao Poon and Kru Nai consisting of a underground section and a elevated section commenced construction in August 2022. As of April 2025, construction has progressed to 53.4% completion with an expected opening date of 2028. However, a road collapse in September 2025 caused the opening date to be delayed.
History Officially named the Chalong Ratchadham Line () – "To Celebrate the Great King's Reign with Righteousness" – but informally known as the "Purple Line", the rapid transit line provides a north–western corridor in Bangkok's Mass Rapid Transit Master Plan. The line also incorporated an extension of the Blue Line from nearby Bang Sue station to Tao Poon Station.
In the 1990s, the plan for the Purple Line was to run from Bang Phut to Bang Sue for , with an extension to Thewet for .
This line was created from the adjustment of the 1994 mass transit rail system master plan, which connected the original extension of the Blue Line from Tao Poon to Bang Yai, while the original Purple Line would have run from the National Library to Tao Poon and the original Orange Line from Samsen (National Library) to Rat Burana, becoming a new line designated as the Purple Line, included in the master plan of the Office of Transport and Traffic Policy and Planning (OTP) for the first time in 2004. Five years later, the line's construction began.
Northern section Construction was divided into six contracts, three of them for civil works. The contracts were signed from late 2009 to early 2010 and completion was originally scheduled for the end of 2014. The third contract included construction of four park and ride buildings at the Khlong Bang Phai, Sam Yaek Bang Yai, Bang Rak Noi Tha It, and Yaek Nonthaburi 1 stations. On 31 March 2017, the fifth contract was effectively terminated and became part of a new Blue Line concession agreement.
The 2011 Thailand floods delayed the construction of the line for nearly one year. In June 2013, five people were injured when six beams fell onto vehicles below Tao Poon station. In July 2014, the civil work was 94 percent complete; in October 2014, civil work was stated to be 99% complete.
The line opened on 6 August 2016, when King Bhumibol Adulyadej appointed Princess Maha Chakri Sirindhorn to represent him in presiding over the opening ceremony and officially pressing the button to open the electric train system. However, the MRT Blue Line extension to Tao poon was delayed, so when it opened the Purple Line could not interchange with the Blue Line as planned. This resulted in low line usage. Even with a reduced fare, the line only attracted about 22,000 passengers daily compared to a goal of 100,000. A shuttle bus service was in operation between Tao Poon MRT station and Bang Sue MRT station to connect with the Blue Line. When the Blue Line extension finally opened a year later, on 11 August 2017, ridership significantly increased. In 2019, daily ridership was 70,000.
Construction contracts ContractNotesContractor(s)Length(km) 1 Phra Nang Klao Bridge to Tao PoonCKTC Joint Venture 13 2 Khlong Bang Phai to Phra Nang Klao BridgeSino-Thai Engineering & Construction 10.75 3 Khlong Bang Phai Depot and Park & Ride buildingsPAR Joint Venture 4 Purple Line Rolling stocks and O&MBangkok Expressway and Metro'Purple Line deal agreed BEM signs 30-year contract with MRTA'. Bangkok Post, 5 September 2013 5 Bang Sue to Tao Poon section and O&M (MRT Blue Line) 6 Track and ElectricalItalian-Thai Development
Southern section As the northern section of the Purple line was built first, the second phase of the Purple Line south from Tao Poon via Rattanakosin – Bangkok's old town to Rat Burana would fully complete the line. The length of the southern extension is : underground, elevated with 17 stations, ten underground and seven elevated. The initial cost of the southern extension is 82 billion baht and with a planned opening by the end of 2027.
The Thai Cabinet was expected to approve the tender in mid 2017 with a tender then to be issued in the second half of 2017.http://www.bangkokpost.com/archive/b358bn-rail-projects-expected-to-go-ahead/1256406. Bangkok Post, 26 May 2017 On 25 July 2017, Cabinet approval was given,The Nation The Nation, 25 July 2017 but the tender was then delayed until 2018.https://www.bangkokpost.com/archive/purple-line-south-link-bid-faces-delay/1357647. Bangkok Post, 10 November 2017https://www.bangkokpost.com/news/transport/1541274/tor-for-slate-of-transport-projects-set-for-fast-track. Bangkok Post, 17 September 2018 By December 2018, a tender had still not been issued and was further delayed. In August 2019, subject to final land acquisition, a March 2020 tender was planned.Member Yappofloyd meeting with MRTA Planning Division on 7 August 2019 at MRTA Headquarters In mid 2020, the Ministry of Transport still aimed for a tendering process within 2020 despite COVID-19 related delays. The MRTA then expected to issue a tender in February 2021.เช็กคืบหน้ารถไฟฟ้าทุกสี ต้นปี 64 เปิดประมูล สีม่วง “เตาปูน-ราษฎร์บูรณะ. Prachachat, 1 December 2020 and if construction had begun in 2021, the extension was projected to enter service sometime in 2027. However, the tender was delayed yet again and subsequently cancelled in August 2021 until it was finally issued in November 2021.
Construction contracts were signed on 11 March 2022 with a construction period of 2005 days for a planned 2027 opening date.
Construction progress Contactors were issued with a Notice to Proceed on 25 April 2022 giving them access to sites along the route with actual construction planned to begin from August 2022. Construction began in early August for two contract sections, 3 & 4. Some 410 lots and 500 buildings will need to be appropriated to build the extension and as of May 2022 many of them were still to be surveyed.
Construction progress was at 3.45% complete at the end of September 2022. By the end of November 2022, construction progress was at 4.30%. At the end of February 2023, construction had progressed to 7.73%.
By the end of May 2023, construction had progressed to 11.50%.
As of December 2024, construction has progressed to 46.3% completion.
As of June 2025, construction has progressed to 57.6% completion with an expected opening date of 2028.
In August 2025, it was reported that only the section between Parliament House station and National Library station will open in 2027. The opening date for the whole extension is delayed to 2030.
Sinkhole incident
On 24 September 2025, at approximately 07:13 local time, a sinkhole measuring about 20 metres in depth opened on a section of Samsen Road in Bangkok. The incident occurred near the construction site of Vajira Hospital Station, part of the southern section of the MRT Purple Line.
Following the collapse, the MRTA suspended construction activities at the affected site to investigate the cause of the incident.
Construction contracts ContractNotesContractor(s)Length(km)Progress(June 2025)Cost 1 Tao Poon to National LibraryCKST Joint Venture 4.8 75.54% ฿19,430 million 2 National Library to Phan Fah 3.44 65.41% ฿15,878 million 3 Phan Fah to Memorial BridgeITD-NWR Joint Venture 3.1 55.18% ฿15,109 million 4 Memorial Bridge to Dao KhanongUnique Construction and Engineering 4.1 59.09% ฿14,982 million 5 Dao Khanong to Kru Nai & DepotItalian-Thai Development 9 36.98% ฿19,904 million 6 Track and Electrical 42.24% ฿3,589 million7Rolling stock TBATBATotal Progress57.36% ฿82,083 million
Stations
CodeStation nameImageOpenedPlatform typePositionPark&RideTransfer NotesEnglishThaiKhlong Bang Phai - Tao Poon: 20.92 km (operational)Khlong Bang Phaiคลองบางไผ่IslandElevatedYesExit to:• Khlong Bang Phai Depot• DHL Supply Chain & DistributionTalad Bang Yaiตลาดบางใหญ่IslandElevated NoExit to:• Big C Extra Bangyai• The Square Bang Yai• Kasemrad International Hospital Ratthanathibet• Home Pro Rattanathibet• Big C Supercenter Rattanathibet 1• Decathlon Bangyai• Index Living Mall Bang Yai• Central Westgate• IKEA Bangyai• Bang Yai MarketSam Yaek Bang Yaiสามแยกบางใหญ่IslandElevatedYesBang PhluบางพลูIslandElevated NoExit to Megahome RattanathibetBang Rak Yaiบางรักใหญ่IslandElevated NoExit to Wat Bang Rak YaiBang Rak Noi Tha Itบางรักน้อย-ท่าอิฐIslandElevatedYesProposed connecting station to (future)Sai Maไทรม้าIslandElevated NoPhra Nang Klao Bridgeสะพานพระนั่งเกล้าIslandElevated NoConnecting station, without paid-area integration to Phra Nang Klao pier for• • Exit to:• Wat Noi Nok• Wat Chaeng Sirisamphan• Tonsak Market• Rajamangala University of Technology Suvarnabhumi - Nonthaburi Campus - North AreaYaek Nonthaburi 1แยกนนทบุรี 1IslandElevatedYesExit to:• Central NorthVille (was known as Central Rattanathibet)• Owl MarketBang KrasorบางกระสอIslandElevated NoExit to:• Big C Supercenter Rattanathibet 2• Grand Richmond Stylish Convention Hotel Formerly Si Phon SawanNonthaburi Civic Centerศูนย์ราชการนนทบุรีIslandElevated NoConnecting station, without paid-area integration, to• , via a 350-metre elevated pedestrian walkway.• (future)Exit to:• National Broadcasting and Telecommunications Commission• Nonthaburi Civic Center• Esplanade Cineplex Ngamwongwan – Khae Rai• Siam Business Administration Nonthaburi Technological College• Makut Rommayasaran ParkMinistry of Public HealthกระทรวงสาธารณสุขIslandElevated NoExit to:• Ministry of Public Health• Srithanya Hospital• Regional Revenue Office 4Yaek Tiwanonแยกติวานนท์IslandElevated NoWong Sawangวงศ์สว่างIslandElevated NoExit to Big C Market Place Wong SawangBang Sonบางซ่อนIslandElevated NoConnecting station, without paid-area integration, to• • SRT Southern LineExit to Bang Son MarketTao PoonเตาปูนIslandElevated NoInterchange station to Exit to:• Tao Poon Market• Lotus's Prachachuen
Under construction
CodeStation nameOpenedPlatform typePositionPark&RideTransfer NotesProgress (June 2026)EnglishThaiTao Poon - Kru Nai: 22.78 km (under construction)Parliament Houseรัฐสภา(expected)IslandUnderground NoExit to:• Thai Parliament• Defence Industrial Department• 4th Armoured Regiment, 1st Division King's Royal Guard• Air Defence Division• Wat Mai Thongsen• Wat Kaew Fah Chulamanee83.10%Sri Yanศรีย่าน(expected)StackedUnderground NoExit to:• Supreme Complex• Makro Samsen• Royal Irrigation Department• Medium Irrigation Water Resources Development Division• Wimol Sriyan Commercial College Formerly Royal Irrigation Department.87.75%Vajira Hospitalวชิรพยาบาล(expected)StackedUnderground NoExit to:• Vajira Hospital• Sukhothai Palace• Market Place Dusit• Suan Dusit University• Saint Gabriel's College83.12%National Libraryหอสมุดแห่งชาติ(expected)SideUnderground NoExit to:• Suan Sunandha Rajabhat University• National Library of Thailand• Rajamangala University of Technology Phra Nakhon • Thewet, Wat Thewarat Kunchorn83.61%Bang Khun Phromบางขุนพรหม(expected)StackedUnderground NoExit to:• Bank of Thailand• Bank of Thailand Museum• Bang Khun Phrom Palace• Wat Sam Phraya84.56%Democracy Monumentอนุสาวรีย์ประชาธิปไตย(expected)StackedUnderground NoInterchange station to (under construction)Exit to:• Mahakan Fort• Rattanakosin Exhibition Hall• Queen Sirikit Gallery• Royal Pavilion Mahajetsadabadin• Wat Saket