# Sukhumvit Line

The Elevated Train in Commemoration of HM the King's 6th Cycle Birthday 1st line, also known as Sukhumvit Line, is one of the rapid transit lines of the BTS Skytrain System in Bangkok, Thailand. The line runs from Siam Station, where it interchanges with the Silom Line, and continues both northwards along Phaya Thai and Phahon Yothin Roads to Khu Khot in Lam Luk Ka District, Pathum Thani, and eastwards along Rama I, Phloen Chit and Sukhumvit Roads, through Bang Na District to Kheha Station in Samut Prakan.
The line was first opened on 5 December 1999, along with the Silom Line. Both lines are operated by the Bangkok Mass Transit System Public Company Limited under a 30-year concession from the Bangkok Metropolitan Administration. When it opened, the line ran from Mo Chit to On Nut covering a total distance of 16.7 km (10.4 mi) with 17 stations. As of October 2024, Sukhumvit Line is one of the main arteries of the Bangkok Mass Rapid Transit System with 900,000 daily passengers per day (combined with the Silom Line). The line rapidly expanded from 2011 until 2021, tripling its distance through three extension projects and reaching a total length of 51.17 km (31.80 mi) with 47 stations.

## History
### Original plan

The Sukhumvit Line's initial proposal was for 12.8 km (8.0 mi) route running from N4 station to E9 station with the depot located at Lumphini Park near the Silom Line. However, this location for the depot faced backlash from the public opinion, which argued that it violated King Rama VI's intention in donating his land to establish Lumphini Park for the public. Additionally, there were protests demanding that the construction of both Skytrain lines be built underground instead of being fully elevated. Therefore, several alternative locations for the depot were considered, such as a vacant land plot in Soi Rangnam owned by the Crowned Property Bureau or the Phra Khanong pumping station in Sukhumvit 50. Ultimately, the Bangkok Metropolitan Administration decided to relocate the depot to the former site of the Northern Bus Terminal (commonly known as the Mo Chit Bus Terminal). With the decision made, the Sukhumvit Line route was extended from N4 station to N8 station. Several changes were made during the construction, as follows:
* N3, N4, E8, and E9 stations were changed from an island platform to side platforms.
* The fully operational year was pushed from the end of 1996 to the end of 1999.
* Station designs were drastically changed from the EIA reports.
* CEN station was moved from the east side of Chaloem Phao junction to the west side.
* E1 station was moved from the east side of the Chit Lom junction to the west side, in front of Mater Dei School, with the two entrances in front of the school being canceled due to protests from school staffs and students concerned about privacy, landscape, and air pollution issues.
* E2 station was originally located between Sukhumvit 2 and Soi Nana but was later moved to the west side of the Chaloem Maha Nakhon Expressway.
* E4 station was moved from the east side of the Asok junction to the west side.

### Extensions
#### Bearing Extension

Construction started in August 2006 on a four-billion baht, 5.25 km (3.26 mi) extension from On Nut to Bearing which included 5 new stations The extension was funded by the BMA. The original scheduled opening date was mid-2009. However, a delay in tendering the contract for the electrical and signaling works resulted in a two-year delay.
The extension did not open until over two years later, on 12 August 2011. The delay in opening prompted the BMA to offer free travel on this extension until the end of 2011 as compensation.

#### Samut Prakan Extension

Construction started in April 2012 on a 12.6 km (7.8 mi), nine station extension from Bearing station to Kheha station. The extension was funded by the MRTA as it is outside BMA city limits, Bangkok Province. Construction was contracted to take 1,350 days and the extension was originally scheduled to open by early 2017. In April 2013, the MRTA awarded Ch Karnchang the contract for track laying and electrical systems.
In June 2014, civil works were stated to be 28.3 percent complete. In August 2016, the BMA agreed to take over the operation of the extension from MRTA. Delays over the agreement of how much the BMA should pay MRTA caused a delay in the commencement of test runs on the extension. Track works were 98% completed by November 2016. The total cost of the extension was estimated at 21.4 billion baht. In January 2017, it was announced that the opening of the extension could be further delayed to 2018-2019 due to budgetary concerns and ongoing disputes between the MRTA and BMA.
The first 1.2 km (0.75 mi) section of the extension to Samrong station opened on 3 April 2017. The full extension to Kheha opened on 6 December 2018.

#### Khu Khot Extension

An 11.4 km, 11 station northern extension from Mo Chit station to Saphan Mai in Don Mueang District had been planned since the Sukhumvit Line opened. Originally, this extension was scheduled to be completed by 2008. However, due to a combination of changes in government, a prolonged environmental study, and problems with locating a suitable train depot the extension was continually delayed. A further 16.5 km (10.3 mi), nine station extension from Saphan Mai to Khu Khot was also planned once the extension to Saphan Mai had been completed.
After multiple delays, in mid-2013 a decision was made to tender extensions (1) and (2) at the same time, by the end of 2013. However, the dissolution of parliament in November 2013 delayed this yet again. A tender was finally released in January 2014 with an April deadline before being delayed until late May 2014 due to concerns from bidders. A military coup in late-May 2014 suspended the bidding process whilst the military administration reviewed all major projects. In late June, the military administration affirmed that the tender would proceed before the end of 2014. In August 2014, the MRTA announced that the new tender deadline was 30 September 2014. Five bidders qualified and the successful bids were announced in December 2014. The tender specified a construction period of 1,350 days.
On 3 April 2015, MRTA signed four contracts for this extension:
| Contract | Notes | Contractors | Length | Costs |
| 1 | Mo Chit to Saphan Mai | Italian-Thai Development | 12.01 km (7.46 mi) | ฿15,269 million |
| 2 | Saphan Mai to Khu Khot | UN-SH-CH joint-venture | 6.11 km (3.80 mi) | ฿6,657 million |
| 3 | Khu Khot Depot and Park & Ride buildings at Yaek Kor Por Aor and Khu Khot stations | STEC-AS joint-venture | | ฿4,019 million |
| 4 | Track laying and system design | STEC-AS joint-venture | | ฿2,841 million |
The MRTA, contactors and Thai Traffic Police met on 2 September 2015 and confirmed construction would begin on 8 September 2015. A flyover at Kasetsart was demolished, which commenced on 12 September 2015.
At 31 December 2017, the progress of civil works construction was at 53.31% according to the MRTA. As of April 2018, the MRTA stated that civil works progress had advanced to 63.27%. As of 30 September 2018, overall construction had progressed to 78.79%. By the end of March 2019, civil construction had nearly been completed having progressed to 99.42%.
Testing of the final 9.8 km, seven-station-section from Wat Phra Sri Mahathat (N17) to Khu Khot (N24) began on 5 October. The final section was officially opened on 16 December 2020 by the Prime Minister.

#### Tamru Extension (future)

There is a plan to extend Sukhumvit Line from Kheha to Tamru for 10.1 km (6.3 mi), including 5 additional stations: Sawangkhaniwat, Mueang Boran, Si Chan Pradit, Bang Pu, and Tamru. This extension has been suspended indefinitely until clarity is reached regarding passenger guarantees.
| Code | Station Name | Station Name | Planned Opening | Platform Type |
| Code | English | Thai | Planned Opening | Platform Type |
| ↓ Continue from Kheha ↓ |||||
| | Sawangkhaniwat | สวางคนิวาส | TBA | Side |
| | Mueang Boran | เมืองโบราณ | TBA | Side |
| | Si Chan Pradit | ศรีจันทร์ประดิษฐ์ | TBA | Side |
| | Bang Pu | บางปู | TBA | Side |
| | Tamru | ตำหรุ | TBA | Side |

#### Lam Luk Ka Extension (future)

There is a plan to extend Sukhumvit Line from Khu Khot Station eastwards for 7.8 km (4.8 mi), including four additional stations: Khlong Sam, Khlong Si, Khlong Ha, and Eastern Ring Road-Lam Luk Ka. This extension has been suspended indefinitely until clarity is reached regarding passenger guarantees.
| Code | Station Name | Station Name | Planned Opening | Platform Type |
| Code | English | Thai | Planned Opening | Platform Type |
| ↓ Continue from Khu Khot ↓ |||||
| | Khlong Sam | คลองสาม | TBA | Side |
| | Khlong Si | คลองสี่ | TBA | Side |
| | Khlong Ha | คลองห้า | TBA | Side |
| | Eastern Ring Road-Lam Luk Ka | วงแหวนตะวันออกลำลูกกา | TBA | Side |

## Opening timeline

| Date | Project | Notes |
| 5 December 1999 | Bangkok Transit System | Full commercial service was commenced from Mo Chit to On Nut stations along with the Silom Line. |
| 12 August 2011 | Bearing Extension | Service extended to Bearing station. |
| 14 May 2010 | | Sukhumvit Line was closed from 17.00 onwards due to 2010 Thai military crackdown. |
| 29 May 2010 | | Resumed normal service. |
| 22 May 2014 | | Sukhumvit Line operated with limited hours from 6:00 to 21:00 due to the curfew, which was a result of the 2014 Thai coup d'état. |
| 28 May 2014 | | Service hours were extended to 06.00-23.00 |
| 14 June 2014 | | Resumed normal service. |
| 3 April 2017 | Samut Prakan Extension | Service extended to Samrong station. |
| 6 December 2018 | Samut Prakan Extension | Shuttle service has been deployed from Samrong to Kheha stations. |
| 11 May 2019 | Samut Prakan Extension | Full commercial service was commenced from Mo Chit to Kheha stations. |
| 9 August 2019 | Khu Khot Extension | Service extended to Ha Yaek Lat Phrao station. |
| 4 December 2019 | Khu Khot Extension | Service extended to Kasetsart University station. |
| 5 June 2020 | Khu Khot Extension | Service extended to Wat Phra Si Mahathat station. |
| 17 October 2020 | | Sukhumvit Line was temporarily closed from 15.00 due to the 2020–2021 Thai protests. |
| 18 October 2020 | | Mo Chit, Ha Yaek Lat Phrao, Phahon Yothin 24, Asok, Udom Suk, and Bang Na stations were temporarily closed due to the protests from 14.30 |
| 16 December 2020 | Khu Khot Extension | Service extended to Khu Khot station. |

## Stations

| Code | Station Name | Station Name | Image | Opened | Platform Type | Park & Ride | Transfers | Notes |
| Code | English | Thai | Image | Opened | Platform Type | Park & Ride | Transfers | Notes |
| | Khu Khot | คูคต | | 16 December 2020; 4 years ago (2020-12-16) | Side | √ | | |
| | Yaek Kor Por Aor | แยก คปอ. | | 16 December 2020; 4 years ago (2020-12-16) | Side | √ | | |
| | Royal Thai Air Force Museum | พิพิธภัณฑ์กองทัพอากาศ | | 16 December 2020; 4 years ago (2020-12-16) | Side | - | | |
| | Bhumibol Adulyadej Hospital | โรงพยาบาลภูมิพลอดุลยเดช | | 16 December 2020; 4 years ago (2020-12-16) | Side | - | | |
| | Saphan Mai | สะพานใหม่ | | 16 December 2020; 4 years ago (2020-12-16) | Side | - | | |
| | Sai Yud | สายหยุด | | 16 December 2020; 4 years ago (2020-12-16) | Side | - | | |
| | Phahon Yothin 59 | พหลโยธิน 59 | | 16 December 2020; 4 years ago (2020-12-16) | Side | - | | |
| | Wat Phra Sri Mahathat | วัดพระศรีมหาธาตุ | | 5 June 2020; 4 years ago (2020-06-05) | Island | - | Interchange station with MRT | |
| | 11th Infantry Regiment | กรมทหารราบที่ 11 | | 5 June 2020; 4 years ago (2020-06-05) | Side | - | | |
| | Bang Bua | บางบัว | | 5 June 2020; 4 years ago (2020-06-05) | Side | - | | |
| | Royal Forest Department | กรมป่าไม้ | | 5 June 2020; 4 years ago (2020-06-05) | Side | - | | |
| | Kasetsart University | มหาวิทยาลัยเกษตรศาสตร์ | | 4 December 2019; 5 years ago (2019-12-04) | Side | - | Connecting station to MRT (future) | |
| | Sena Nikhom | เสนานิคม | | 4 December 2019; 5 years ago (2019-12-04) | Side | - | | |
| | Ratchayothin | รัชโยธิน | | 4 December 2019; 5 years ago (2019-12-04) | Side | - | Proposed connecting station to MRT . (Yellow Line (Bangkok) § Northern extension) | |
| | Phahon Yothin 24 | พหลโยธิน 24 | | 4 December 2019; 5 years ago (2019-12-04) | Side | - | Proposed connecting station to MRT . (Yellow Line (Bangkok) § Northern extension) | |
| | Ha Yaek Lat Phrao | ห้าแยกลาดพร้าว | | 9 August 2019; 5 years ago (2019-08-09) | Island | - | Connecting station to Phahon Yothin for MRT , via a 330-metre elevated pedestrian walkway. | |
| | Mo Chit | หมอชิต | | 5 December 1999; 25 years ago (1999-12-05) | Side | √ | Connecting station to Chatuchak Park for MRT | |
| | Saphan Khwai | สะพานควาย | | 5 December 1999; 25 years ago (1999-12-05) | Side | - | | |
| | Sena Ruam | เสนาร่วม | | TBA | Side | - | | Provisional station |
| | Ari | อารีย์ | | 5 December 1999; 25 years ago (1999-12-05) | Side | - | | |
| | Sanam Pao | สนามเป้า | | 5 December 1999; 25 years ago (1999-12-05) | Side | - | | |
| | Victory Monument | อนุสาวรีย์ชัยสมรภูมิ | | 5 December 1999; 25 years ago (1999-12-05) | Side | - | | |
| | Phaya Thai | พญาไท | | 5 December 1999; 25 years ago (1999-12-05) | Side | - | Connecting station to; • ARL • SRT (future) | |
| | Ratchathewi | ราชเทวี | | 5 December 1999; 25 years ago (1999-12-05) | Side | - | Connecting station to MRT (under construction) | |
| | Siam | สยาม | | 5 December 1999; 25 years ago (1999-12-05) | Stacked Island | - | Cross-platform interchange with BTS |
| | Chit Lom | ชิดลม | | 5 December 1999; 25 years ago (1999-12-05) | Side | - | | |
| | Phloen Chit | เพลินจิต | | 5 December 1999; 25 years ago (1999-12-05) | Side | - | | |
| | Nana | นานา | | 5 December 1999; 25 years ago (1999-12-05) | Side | - | | |
| | Asok | อโศก | | 5 December 1999; 25 years ago (1999-12-05) | Side | - | Connecting station to Sukhumvit for MRT | |
| | Phrom Phong | พร้อมพงษ์ | | 5 December 1999; 25 years ago (1999-12-05) | Side | - | | |
| | Thong Lo | ทองหล่อ | | 5 December 1999; 25 years ago (1999-12-05) | Side | - | | |
| | Ekkamai | เอกมัย | | 5 December 1999; 25 years ago (1999-12-05) | Side | - | Connecting station to MRL (north section; future) | |
| | Phra Khanong | พระโขนง | | 5 December 1999; 25 years ago (1999-12-05) | Side | - | Connecting station to MRL (south section; future) | |
| | On Nut | อ่อนนุช | | 5 December 1999; 25 years ago (1999-12-05) | Side | - | | |
| | Bang Chak | บางจาก | | 12 August 2011; 13 years ago (2011-08-12) | Side | - | | |
| | Punnawithi | ปุณณวิถี | | 12 August 2011; 13 years ago (2011-08-12) | Side | - | | |
| | Udom Suk | อุดมสุข | | 12 August 2011; 13 years ago (2011-08-12) | Side | - | | |
| | Bang Na | บางนา | | 12 August 2011; 13 years ago (2011-08-12) | Side | - | Connecting station to Bang Na-Suvarnabhumi LRT (future) | |
| | Bearing | แบริ่ง | | 12 August 2011; 13 years ago (2011-08-12) | Side | - | | |
| | Samrong | สำโรง | | 3 April 2017; 7 years ago (2017-04-03) | Island | - | Interchange station to MRT via transfer gates | |
| | Pu Chao | ปู่เจ้า | | 6 December 2018; 6 years ago (2018-12-06) | Side | - | | |
| | Chang Erawan | ช้างเอราวัณ | | 6 December 2018; 6 years ago (2018-12-06) | Side | - | | |
| | Royal Thai Naval Academy | โรงเรียนนายเรือ | | 6 December 2018; 6 years ago (2018-12-06) | Side | - | | |
| | Pak Nam | ปากน้ำ | | 6 December 2018; 6 years ago (2018-12-06) | Side | - | | |
| | Srinagarindra | ศรีนครินทร์ | | 6 December 2018; 6 years ago (2018-12-06) | Side | - | | |
| | Phraek Sa | แพรกษา | | 6 December 2018; 6 years ago (2018-12-06) | Side | - | | |
| | Sai Luat | สายลวด | | 6 December 2018; 6 years ago (2018-12-06) | Side | - | | |
| | Kheha | เคหะฯ | | 6 December 2018; 6 years ago (2018-12-06) | Side | √ | | |

## Operation

The Sukhumvit Line operates from 06:00 to 24:00 every day. During rush hour, there are two main service patterns:
* Full Line operation from Khu Khot to Kheha
* Short-run train from Mo Chit to Samrong
Apart from these two service patterns, some trains might terminate at Kasetsart University and Ha Yaek Lat Phrao or operate as through-running trains to/from Bang Wa station on the Silom Line.

### Headways

Sukhumvit Line headway :
| Time | Section | Headway (Minutes:Seconds) |
| Monday - Friday |||
| 06:00 - 07:00 | Full Line | 05:00 |
| 07:00 - 09:00 | Mo Chit - Samrong | 02:40 |
| 07:00 - 09:00 | Full Line | 05:20 |
| 09:00 - 09:30 | Full Line | 03:35 |
| 09:30 - 16:00 | Full Line | 06:30 |
| 16:00 - 16:30 | Full Line | 04:25 |
| 16:30 - 20:00 | Mo Chit - Samrong | 02:40 |
| 16:30 - 20:00 | Full Line | 05:20 |
| 20:00 - 21:00 | Full Line | 04:25 |
| 21:00 - 22:00 | Full Line | 06:00 |
| 22:00 - 24:00 | Full Line | 08:00 |
| Saturday to Sunday and Public Holiday |||
| 06:00 - 08:00 | Full Line | 07:00 |
| 08:00 - 11:00 | Full Line | 05:55 |
| 11:00 - 21:00 | Mo Chit - Samrong | 04:30 |
| 11:00 - 21:00 | Full Line | 06:00 |
| 21:00 - 22:00 | Full Line | 07:00 |
| 22:00 - 24:00 | Full Line | 08:00 |

## Gallery

* Sukhumvit Line viaduct at Lak Si roundabout.
* EMU-A2 with Elephant Building behind at Ratchayothin station.
* Mo Chit Depot in 2013.
* EMU-B3 at Victory Monument.
* EMU-B1/B2 (left) and EMU-B3 at Victory Monument station.
* View of Pathum Wan district.
* Sukhumvit Line viaduct from Pathum Wan Skywalk.
* The upper-level platform at Siam station in 2007, before the installation of platform screen doors
* View from Chit Lom station.
* 3-cars EMU-A1 from 2007
* Phloen Chit Road with Sukhumvit Line viaduct above.
* Sukhumvit Line at Asok Junction.
* EmSphere from Phrom Phong station.
* EMU-A1 at Bang Na station with BITEC behind.
* EMU-A2 departing Samrong station.
* Sukhumvit Line viaduct runs through Samut Prakan province.