Purple Line (Bangkok)
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.
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.
Route alignment
The Purple line starts from Khlong Bang Phai station in Bang Bua Thong District. The line travels south along Kanchanaphisek Road before turning eastward near Central WestGate, onto Rattanathibet Road. It continues along Rattanathibet Road, passing through a large residential area in Bang Yai District and crosses the Chao Phraya River on a bridge parallel to the Phra Nang Klao Bridge and runs towards Nonthaburi Civic Center station. The line then turns southward onto Tiwanon Road, passing the Ministry of Public Health and turns southeast onto Krung Thep-Nonthaburi Road, entering Yaek Tiwanon station. The line then enters Bangkok city limits at Bang Sue district and passes Bang Son station before terminating at the upper platforms of Tao Poon station, with a total length of, serving 16 stations.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 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 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
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. On 25 July 2017, Cabinet approval was given, but the tender was then delayed until 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. 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. 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
Stations
Under construction
Infrastructure
Depot
The Khlong Bang Phai Depot serves as the main maintenance facility for the entire MRT Purple Line. It is on Kanchanaphisek Road, near Khlong Bang Phai Station. Additionally, the Kru Nai stabling yard is currently under construction as part of the Purple Line Southern Section project. It is near the southern section of Kanchanaphisek Road in Phra Pradaeng District, Samut Prakan Province.Park & Ride
There are currently four Park & Ride facilities along the MRT Purple Line, at Khlong Bang Phai, Sam Yaek Bang Yai, Bang Rak Noi Tha It, and Yaek Nonthaburi 1 stations. Two additional facilities are under construction at Bang Pakok and Rat Burana stations as part of the Purple Line Southern Section project.Station
The MRT Purple Line comprises 33 stations, with 16 currently in operation since 2016—all of which are elevated. The remaining 17 stations are under construction and expected to be completed by 2029, consisting of 10 underground and 7 elevated stations.Station structures on the MRT Purple Line North Section range from 300 to 400 meters in length and approximately 18 meters in width. In the Southern Section, underground stations typically measure 250 meters in length and 20 meters in width, while elevated stations are 153 meters long and 25 meters wide. All stations are designed to accommodate a maximum of six cars per train. Elevated stations are equipped with half-height platform screen doors, while underground stations will be fitted with full-height platform screen doors. In addition, the entrances to the stations are designed to be about one meter above ground level, taking into account the highest recorded flood levels in Bangkok to prepare for potential future flooding events.
Rolling stock
In November 2013, BEM contracted with Marubeni Corp, Toshiba Corp, and East Japan Railway Company to install E&S systems, supply 21 three-car trains rolling stock, and provide maintenance for 10 years as part of a contract worth 12.6 billion baht. East Japan Railway train manufacturing subsidiary J-TREC built them in Yokohama with the first sets delivered in early 2016. The trains are owned by the MRTA which paid for the rolling stock at BEMs request. The southern extension will acquire 17 additional trains, along with the current ones, to create a total of 38 trains.In total, line is service by 21 three-car trains. Trains are powered by 750 V DC via third rail system, are air-conditioned and capable of traveling at up to.