# SRT Light Red Line

The SRT Light Red Line, or Nakhon Withi Line (Thai: รถไฟชานเมือง สายนครวิถี) is a 15 km (9.3 mi) between Krung Thep Aphiwat Central Terminal and Taling Chan and is part of the SRT Red Lines suburban railway system serving the greater Bangkok Metropolitan Region.
An initial segment from Taling Chan to Bang Son previously opened for limited, free trial service between 5 December 2012 and 13 January 2014 with only 12 services a day until all services were fully suspended due to the lack of rolling stock. After a much-delayed completion of the electrification of the line and the construction of Krung Thep Aphiwat Central Terminal, the line finally opened for trial operations on 2 August 2021. Full commercial services commenced on 29 November 2021.
A much delayed 15 km (9.3 mi) western extension of the line from Taling Chan to Salaya was due to be tendered in June 2022. However, this was later delayed to December 2022 and then until February 2023. With the 14 May 2023 national elections and the ongoing delays in the formation of a new government, it is unlikely that the tenders will be issued until late 2023. In late June, a MOT source expressed that the extension is likely be taken to Cabinet for approval in October 2023 and if approved, a tender could be issued in the first quarter of 2024.
When fully completed, the line will run east–west from Salaya, Thailand in Phutthamonthon District of Nakhon Pathom Province to Hua Mak railway station in Bangkok.

## Route alignment

The 15 km (9.3 mi) section runs from Krung Thep Aphiwat Central Terminal (the new Intercity Terminal in Chatuchak District) to Bang Son where it interchanges with the MRT Purple Line. It then continues west and crosses the Chao Phraya River to the Thonburi side of Bangkok before continuing farther west to Taling Chan where it terminates. Krung Thep Aphiwat Central Terminal Intercity Terminal provides interchange with the SRT Dark Red Line and MRT Blue Line. The line will be extended 14.8 km (9.2 mi) west to Sala Ya in Phutthamonthon District of Nakhon Pathom Province. Finally, the line will be extended south from Krung Thep Aphiwat Central Terminal via Phaya Thai and then east to Hua Mak Railway Station in the east of Bangkok where it will interchange with the MRT Yellow Line.

## History

In 2004, in conjunction with OTP, the SRT began formulating plans for a new, modern suburban network in Bangkok along existing SRT alignments to replace the existing, limited services. On 7 November 2006, the Thai Cabinet passed a resolution to approve the framework of the new network with the SRT Light Red line being DMU operations while the SRT Dark Red Light would be EMU. The Cabinet approved the line on 22 May 2007 with a budget of 13.133 billion baht. At the time, it was expected that the full iine could be completed within 15–20 years. Contracts for construction of the initial section from Taling Chan to Bang Sue were awarded by the SRT on 29 September 2009. The contract was signed on 15 December 2008, with the contract awarded to the Unique-Chun Wo consortium.

### Construction

Construction started in early 2010 after some site access delays related to slum dwellers who had been residing various sections of SRT land for many years. Works progressed well but were thereafter delayed for a few months due to the late 2011 floods in Bangkok with floodwaters inundated on parts of the route. Construction was completed by the 3rd quarter of 2012. Testing began in September 2012 for a 3-month period.

### 2012-4 trial operation and suspension

The line opened for free limited trial service on 5 December 2012 between Taling Chan Station and Bang Son Station. The line was operated with 2 refurbished DMUs running a very limited service. There were only 6 services each way a day every 60 minutes from 6am to 8am and from 4pm to 7pm. As such, only a few hundred passengers a day rode the service. On 14 September 2013, weekend services were cancelled. Effective 13 January 2014, all services were suspended until electrification works could be completed and rolling stock procured which was expected to be by the end of 2018.

### Electrification and 2021 opening

The reopening of the SRT Light Red line was contingent upon the completion of the new Krung Thep Aphiwat Central Terminal, delivery of rolling stock and installation of the overhead catenary electrical system between Bang Sue–Taling Chan which was funded as part of the SRT Dark Red Line contract 3 as the SRT had subsequently decided to change the line from DMU to EMU operations. Full electrification was planned to be completed by 2020 when the SRT Dark Red line was completed. By the end of September 2019, Electrical and Signaling installation was at 45.60%.
By June 2020, installation of the catenary system was at 76.82%. The line was expected to reopen in January 2021 after test runs began in late October 2020. In mid-November 2020, the Minister of Transport announced that free trial operations would operate from March to May 2021 with full-service operations expected in November 2021. In late February 2021, the SRT confirmed that free trial operations would commence on 26 March 2021 with full commercial operations starting on 28 July 2021. In July, the SRT postponed the service and the free trial operations commenced on 2 August 2021 with full commercial operations due to start on 28 November 2021.

## Rolling stock

The 3rd contract for the SRT Dark Red Line was for the electrical and mechanical (E&M) systems and procuring EMU rolling stock for both the SRT Light Red and SRT Dark Red lines with an overhead catenary electrical system at 25 kV 50 Hz AC. In April 2014, only 2 bidders remained but one of the bidding consortiums was disqualified on due to the fact that one of the consortium members (Marubeni Corporation) had convictions for bribery in an Indonesian bidding process.
This left the MHSC Consortium (consisting of Mitsubishi Heavy Industries, Hitachi, and Sumitomo Corporation) as the sole bidder qualified for the contract. However, their bid of 28,899 billion Baht was above the SRT median price of 26 billion baht which was set in 2010. The MHSC Consortium argued that their bid reflected 2013 prices after the national minimum wage increase from 1 January 2012. Finally in July 2014, after a 2-year delay in the bidding process JICA approved the loan for Contract 3. However, the coup of May 2014 delayed finalization leading to further review and negotiations. By mid-2016, negotiations had concluded and Hitachi promised that all rolling stock for the Dark Red line would be delivered by 2020. The contract specified 25 EMUs consisting of ten 4 car sets and fifteen 6 car sets for 130 cars in total.
In late September 2019, the first 2 sets of rolling stock were shipped from Japan and both arrived in Thailand at Laem Chabang port on 12 October 2019 for shipment to Bangkok. By March 2020, 5 sets had been delivered. As of July 2020, 13 sets - 7 of the 6 car sets and 6 of the 4 car sets - of the ordered 25 sets of rolling stock had been delivered with a further 2 sets due to be delivered by August 2020. By the end of September 2020, 21 sets had been delivered - 13 of the 6 car sets and 8 of the 4 car sets - with the final 4 sets to be delivered in October.

## Operation

As of 2024, services operate from 5am to 12am with headways of 20 minutes. Distance-based fares range from 12 to 20 baht (previously 42 baht). The SRT also offers a 30 day integrated Transit Pass which can be used for 50 trips and for travel on all BMTA buses.
SRT long distance trains on the Southern Line terminating at Krung Thep Aphiwat share the same tracks.

### Ridership

On the first full day of free trial operations on 3 August 2021 total passengers numbered 302, on 4 August this increased to 331 passengers. By the end of September, this had increased to around 500-550 passengers a day. For the first 10 months of operations to September 2022 both Red lines carried over 3.2 million passengers and services ran on time 99.45% of the time according to the SRT. However, a small percentage of this were passengers on the Light Red line. By the end of September 2022 the line averaged only 23,000 passenegers a month. In November 2022, the SRT introduced regular DMU services from Thonburi via Taling Chan to Nakhon Pathom to connect with the Light Red line. Afterwards, daily passengers numbers rose significantly from an average of 300 a day to between 1400-1500 passengers a day in January 2023.

## Future extensions

In July 2016, the cabinet approved the construction of the Bang Sue–Phaya Thai–Makkasan–Hua Mak segment. However, the 15 km (9.3 mi), 4 station western extension Taling Chan to Salaya was due to be tendered first by September 2018 and then slated for the 2nd half of 2019. However, the tender was further delayed until 2021 as the Transport Minister has requested the new Department of Railways to investigate conducting PPP tenders for this extension. The decision to change the extensions to PPP projects and tender out the operation of the line with a 50 year concession was opposed by the SRT and SRT union. On 10 February 2021, the Department of Railways announced that in April 2021 the SRT would issue the tenders for the west extensions to Salaya and from Taling Chan to Siriraj. However, the PPP tender process was subject to further review.
In October 2021, the SRT announced that the PPP tenders would not be released until June 2022 with the aim to sign contracts for the extensions (with 50 year leases) in July 2023. However, this was delayed yet again to an initial October 2022 tender release and later a December 2022 date. In late October 2022, the SRT again delayed the tender time frame to February 2023 with an aim to sign contracts by May 2023 but the time frame was contingent on new Cabinet approval of an updated budget for the extension. At the same time, the SRT decided to defer the bidding for the 50 year operation concession and new EMUs to December 2024. Once the concession is contracted the SRTET will cease to operate the line.
With the 14 May 2023 national elections and the expected time frame in the formation of a new government, it is unlikely that the tenders will be issued until late 2023. In late June, a MOT source expressed that the extension is likely be submitted to Cabinet in October 2023 for approval of a new budget of 10.67 billion baht to build the Salaya extension. If approved, a tender could be issued in the first quarter of 2024.
Construction segments based on M-Map:
| Phase | Segment | Length | Progress |
| I | Bang Sue–Taling Chan | 15.26 km (9.48 mi) | Full operation: 29 November 2021 |
| II | Taling Chan–Salaya | 14.8 km (9.20 mi) | Tender in late 2023 |
| III | Taling Chan–Siraj | 5.7 km (3.54 mi) | Tender delayed due to redesign |
| IV | Bang Sue–Hua Mak | 20.14 km (12.51 mi) | Tender in late 2023 |
| V | Salaya–Nakhon Pathom | 30 km (18.64 mi) | Planned long-term extension |

### Phase II Taling Chan–Salaya Extension

The SRT Light Red Line is planned to be extended by 14.8 km (9.2 mi) west to Salaya. 4 stations are planned be built along the existing SRT corridor;
* 1) Ban Chimphli station
* 2) Kanchanaphisek (Phutthamonthon Sai 2)
* 3) Sala Thammasop
* 4) Salaya
The western extension from Taling Chan to Salaya was originally planned to be tendered by September 2018 after receiving Thai Cabinet approval in July 2016. This was then delayed to the 2nd half of 2019. However, the tender has further been delayed until 2021 as the Transport Minister has requested the new Department of Railways to investigate conducting PPP tenders for this extension.

### Infill stations

Two additional infill stations, Rama 6 bridge and Bang Kruay (EGAT) on either side of the Chao Praya river, were part of the original plans but deferred until ridership grew will be tendered as part of the 15 km Salaya western extension tender.

### Phase III Taling Chan–Siriraj spur line

The SRT operates existing intercity services from Thonburi station to Kanchanaburi. This line is planned to be converted to a spur line of the existing Light Red line, from Taling Chan to Thonburi/Siriraj. In August 2012, the SRT proposed that 3 stations be built for this 5.7 km route:
* 1) Taling Chan Floating Market station at Bang Ramat
* 2) Charansanitwongse station (interchange with the MRT Blue Line)
* 3) Thonburi/Siriraj station (interchange with the MRT Orange Line). Originally the MRT Orange Line was planned to be built along this alignment to Taling Chan. This spur line will be constructed once the extension to Salaya has started construction.

### Phase IV Bang Sue–Hua Mak

The eastern extension will be 18.8 km (11.7 mi) long with stations at Ratchawithi, Phaya Thai, Makkasan, and Hua Mak. It will have a narrow right of way given the current ARL viaduct and ARL stations.

## Stations
### Western stations

| Code | Station Name | Thai | Transfer | Province |
| SRT Light Red Line |||||||
| RW01 | Bang Sue (Krung Thep Aphiwat) | กรุงเทพอภิวัฒน์ | SRT  ARL (preliminary works) MRT : Bang Sue | Bangkok |
| RW02 | Bang Son | บางซ่อน | MRT : Bang Son | Bangkok |
| RW03 | Phra Ram 6 | พระราม 6 | | Bangkok |
| RW04 | Bang Kruai-EGAT | บางกรวย-กฟผ. | | Nonthaburi |
| RW05 | Bang Bamru | บางบำหรุ | | Bangkok |
| RW06 | Taling Chan | ตลิ่งชัน | BTS : Talingchan (proposed) | Bangkok |
| RW07 | Ban Chimphli | บ้านฉิมพลี | | Bangkok |
| RW08 | Kanchanaphisek | กาญจนาภิเษก | | Bangkok |
| RW09 | Sala Thammasop | ศาลาธรรมสพน์ | | Bangkok |
| RW10 | Salaya | ศาลายา | | Nakhon Pathom |
| Talingchan–Siriraj Branch Line |||||||
| RW06 | Taling Chan | ตลิ่งชัน | BTS : Talingchan (proposed) | Bangkok |
| RWS01 | Talat Nam Taling Chan | ตลาดน้ำตลิ่งชัน | | Bangkok |
| RWS02 | Charan Sanitwong | จรัญสนิทวงศ์ | MRT : Bang Khun Non MRT : Bang Khun Non (tender awarded) | Bangkok |
| RWS03 | Siriraj | ศิริราช | MRT : Siriraj (tender awarded) | Bangkok |

### Eastern stations

| Code | Station Name | Thai | Transfer | Province |
| SRT Light Red Line |||||||
| RE01 | Bang Sue (Krung Thep Aphiwat) | กรุงเทพอภิวัฒน์ | SRT  ARL (preliminary works) MRT : Bang Sue | Bangkok |
| RE02 | Pradiphat | ประดิพัทธ์ | SRT (approved) | Bangkok |
| RE03 | Sam Sen | สามเสน | SRT (approved) | Bangkok |
| RE04 | Ratchawithi | ราชวิถี | SRT (approved) | Bangkok |
| RE05 | Phaya Thai | พญาไท | BTS : Phaya Thai ARL : Phaya Thai | Bangkok |
| RE06 | Makkasan | มักกะสัน | ARL : Makkasan (City Air Terminal) MRT : Phetchaburi | Bangkok |
| RE07 | Sun Wichai | ศูนย์วิจัย | MRL (proposed) | Bangkok |
| RE08 | Ramkhamhaeng | รามคำแหง | ARL : Ramkhamhaeng | Bangkok |
| RE09 | Hua Mak | หัวหมาก | ARL : Hua Mak MRT : Hua Mak | Bangkok |