The MRT Yellow Line () or MRT Nakkhara Phiphat Line () is an elevated monorail line in Bangkok and Samut Prakan Province, Thailand. It is the third line of the MRT rapid transit system. The line has 23 stations and cost 55 billion baht. The line was originally proposed in 2005 by the Office of Transport and Traffic Policy and Planning to be a heavy rail underground line along Lat Phrao road which was then elevated from Lam Sali Intersection to Samrong. However, it was decided in 2012 to build an elevated monorail line for the whole length in order to reduce construction costs.
The Yellow Line provides mass transit along the heavily congested Lat Phrao Road and Srinagarindra Road corridors. The line links 6 other lines; the MRT Blue Line, interchange with the MRT Orange Line (which is under construction), the planned MRT Grey Line and MRT Brown Line, the Airport Rail Link (Bangkok) and finally the BTS Sukhumvit Line. As such, it is an important cross city link in the middle north-eastern and eastern areas of Bangkok.
Preliminary site works began in late 2017 with major construction work starting from March 2018. In October 2020, the BSR stated that they plan to open the first section of the Yellow Line by October 2021 with initial operations running from Samrong to Si Iam. The line was then planned to fully open in July 2022. However, due to COVID-19 outbreaks in Bangkok delaying construction with sites closed, the BSR stated that the first section of the line would not open until July 2022. On 29 November 2021, daily testing began on a section of the line between the depot at Si Iam and Srinagarindra 38 station. Testing was expanded after a 3-month period.
In mid-April 2022, the director of EBM/BSR, Mr Surapong Laoha-Unya, stated that further labour and installation delays would mean that the line would now not open until September 2022. Construction had progressed to 99.02% as of the end of April 2023.
After repeated delays, the line partially opened to the public for free trial rides on 3 June 2023 from Hua Mak to Samrong, having done a private trial ride between Kalantan and Samrong for the press the day before. Trial rides for Phawana to Hua Mak section began on 12 June, while the final section between Phawana and Lat Phrao station opened on 19 June.
Rabbit Card are accepted on the MRT Yellow Line, which is also accepted on the BTS Skytrain and MRT Pink Line. This is because the operator is a subsidiary of BTS Group Holdings, which operates the BTS Skytrain. EMV contactless cards are also accepted.
Following two incidents of operational failure in January and March 2024, Vajiralongkorn, the king of Thailand, bestowed an auspicious name upon Bangkok's Yellow Line monorail on 30 May 2024. The line has been officially renamed "Nakkhara Phiphat" (Pali: Nagara Vivaḍḍhana), meaning "prosperity of the city," by royal command.
Route alignment The line starts at the intersection of Ratchadaphisek and Lat Phrao roads where it interchanges with the MRT Blue Line at Lat Phrao station. The line then heads east along Lat Phrao road to Bang Kapi intersection and south to Lam Sali station to interchange with the MRT Orange Line and the future MRT Brown Line. The line continues further south along Srinagarindra Road to Hua Mak where it interchanges with the Airport Rail Link at Hua Mak station.
From Hua Mak, the route continues south along Srinagarindra Road past the Debaratna (Bang Na-Trat) Road all the way to Thepharak Road in Samut Prakan Province, then heading west along Thepharak Road where it terminates at Samrong and interchanges with Samrong of the BTS Sukhumvit Line.
The line stretches from Lat Phrao (YL1) to Samrong (YL23) and the depot is located at Debaratana Road adjacent to Si Iam station (YL17).
History The Yellow line was first proposed in the mid-1990s as a monorail line by Japanese consultants with little or no progress for 10 years. In 2004, the Office of Transport and Traffic Policy and Planning (OTP) reworked the proposal as a heavy rail line with underground and elevated sections as part of the 10 line metro plan which was taken to the February 2005 election. In 2009, it was suggested to change the line to an elevated monorail line as a cost saving measure. In December 2011, the MRTA was instructed by the MOT to divide the Yellow Line into two phases for tender and construction purposes and to reduce land appropriation costs. In June 2012, the MRTA contracted consultants to undertake detailed designs of the line. In February 2013, OTP stated that the tender for the Yellow Line should be ready by late 2013 for tender in early 2014. By August 2013, this timeline had changed to a mid 2014 tender date.
However, similar to the MRT Pink Line, delays in finalising the technical requirements of the tender in relation to the selection of monorail rolling stock which determines the type of track to be constructed resulted in further delays. The subsequent political turmoil of late 2013 and early 2014 caused even more delays. Thereafter, a coup in May 2014 resulted in a new military administration and the tender being deferred while a review of all mass transit projects was undertaken for a period of 18 months. The MRTA was instructed by the junta government to change to a PPP tender process which was subsequently not released until mid-2016. In early December 2016, The BSR consortium consisting of BTS Group Holdings (75% majority stake) with Sino-Thai Engineering and Construction (STEC), and Ratchaburi Electricity Generation Holding (RATCH), won the bid to construct and operate the Yellow Line. The BSR also won the bid to build and operate the MRT Pink Line.
On June 16, 2017, the contract was signed for the project between the Mass Rapid Transit Authority of Thailand and BSR consortium. The BSR established the Eastern Bangkok Monorail Company Limited (EBM) to operate the line. A proposed 2 station extension of the route north from the Lat Phrao terminus to link to the BTS Sukhumvit Line at Ratchayothin station has also been proposed by the BSR Joint Venture. However, this extension is opposed by the MRT Blue Line operator BEM due to concerns regarding loss of revenue.Author meeting with MRTA planning division on 7 August 2019 at MTRA Headquarters
Construction of the Yellow Line began in March 2018.
The public trial run started on 3 June 2023, between Hua Mak and Samrong. The Phawana-Si Kritha section opened on 12 June, while Lat Phrao station opened on 19 June.Bangkok opens two new monorails Tramways & Urban Transit issue 1028 August 2023 page 292
As of June 2024, passengers are required to change train due to technical difficulties, sections of station runs in different frequency. Latphrao to Huamak runs every 5 minutes, Huamak to Sri Iam runs every 25 minutes and from Sri Iam to the terminus Samrong every 10 minutes. Yellow maintenance carts can be seen along the line from Huamak to Samrong.
Northern extension A proposed 2-station extension of the route north from the current Ratchada terminus to link to the BTS Sukhumvit Line Extension at Ratchayothin station has also been proposed by the BSR Joint Venture. However, this extension is opposed by the MRT Blue Line operator BEM, estimating about 988 million baht loss on the extension's first year of service and 2.7 billion baht throughout the 30-year concession period.
The extension was approved in February 2021, with construction set to be completed in 2024. However, EBM has repeatedly denied MRTA's request to provide compensation for BEM, which may result in a cancellation of the extension if no decision has been made. Regardless, due to lower-than-expected passenger numbers, MRTA decided to put the extension plan on hold, as the Yellow Line needs at least 100,000 passengers per day to ensure the investment feasibility of the project. CodeStation NameTransfersEnglishThai↓ Continue from Lat Phrao ↓Chankasemจันทรเกษม Phahon Yothin 24 / Ratchayothinพหลโยธิน 24 / รัชโยธิน Connecting station to either Phahon Yothin 24 or Ratchayothin BTS station for
Southern extension A future extension from Samrong station across the Chao Phraya River to link with the MRT Purple Line at Rat Burana was canvassed by the OTP in the early 2010s. However, the current location and design of Samrong station excludes any further extension of the line west of Sukhumvit Road.
List of stations
CodeStation NameImageOpenedPlatform TypePark & RideTransfersNotesEnglishThai Lat Phraoลาดพร้าวSide√Connecting station to Exit to:• Ratchada-Lat Phrao Intersection• The Bazaar Hotel Bangkok• Gourmet Market MRT Lat Phrao PhawanaภาวนาSide - Chok Chai 4โชคชัย 4Side -Exit to:• Chok Chai 4 Market• Council of Engineers• Royal Thai Survey Department Section 1 Lat Phrao 71ลาดพร้าว 71Side -Proposed connecting station to Lat Phrao 83ลาดพร้าว 83Side -Exit to BigC Supercenter Ladprao 1 Mahat ThaiมหาดไทยSide -Exit to:• Ladprao General Hospital• Foodland Lat Phrao• Green Hospital Ladprao General Lat Phrao 101ลาดพร้าว 101Side - Bang KapiบางกะปิSide -Connecting station to The Mall Bangkapi pier for Khlong Saen Saep boat serviceExit to:• Makro Ladprao• Tawanna Market• The Mall Lifestore Bangkapi• Happyland Center• Lotus's Bangkapi• Bang Kapi Market Yaek Lam SaliแยกลำสาลีSide -Connecting station to• (under construction)• (future) Si KrithaศรีกรีฑาSide -Exit to:• Syn Mun Kong Insurance Headquarter• B.Grimm Technologies Headquarter• Piyaphirom Park Hua MakหัวหมากSide -Connecting station to • (future)• • SRT Eastern LineExit to MaxValu Supermarket KalantanกลันตันSide -Exit to Thanya Park Si NutศรีนุชSide - Srinagarindra 38 ศรีนครินทร์ 38Side - Suan Luang Rama IXสวนหลวง ร.9Side -Exit to:• Seacon Square• Train Night Market Srinagarindra• Paradise Park• Suan Luang Rama IX (Magnolia Gate) Si UdomศรีอุดมSide -Exit to Synphaet Srinagarindra Hospital Si Iamศรีเอี่ยมSide√Proposed connecting station to (future)Exit to:• Wat Sri IamL• Si Iam MRT Depot• AIA East Gateway• Ample Tower Si La SalleศรีลาซาลSide - Si Bearingศรีแบริ่งSide - Si Danศรีด่านSide -Exit to JAS Urban Srinakarin Si ThephaศรีเทพาSide - ThipphawanทิพวัลSide - SamrongสำโรงSide -Interchange station with via transfer gates.Exit to:• Imperial World Samrong• Big C Supercenter Samrong 1• Iamcharoen Market• Samrong Fresh Market• Samrong Medical Hospital
Rolling stock
BSR selected Bombardier Innovia Monorail 300 rolling stock for the Yellow line. The BSR announced that they would purchase 28 4-car sets to operate the Yellow line. The trains were manufactured by CRRC Puzhen Bombardier Transportation Systems (joint venture of Bombardier Transportation and CRRC Nanjing Puzhen) in Wuhu, Anhui, China. The first set was assembled and shipped on 4 September 2020 with delivery to Thailand at the end of September 2020.https://ah.sina.com.cn/news/2020-09-04/detail-iivhvpwy4950163.shtml ah.sina.com.au, 4 September 2020 The first set arrived in Thailand on 1 October 2020 at Laem Chabang port with a handover ceremony attended by the then Prime Minister Prayut Chan-o-cha, BTSC Chairman, MRTA and Canadian Ambassador. Two more sets arrived in mid December 2020 for a total of 5 sets by the end of 2020. By July 2021, 8 sets had been delivered and were being tested. As of the end of October 2021, 12 sets had been delivered. By the end of November 2021, the BSR stated that 20 sets had been delivered with the remaining sets expected to be fully delivered by the end of March 2022. However, as of mid April 2022 only 26 sets had been received and were progressing undergoing testing. The remaining sets were expected to be delivered by July 2022.
Technical Characteristics Low profile vehicles/low floor height above beam Distinct sloped nose/end-cap Inter-car walkthrough Rubber-tires and permanent magnet motor Aluminium body, steel underframe, composite end cap