Extension to Tao Poon

As part of the rapid transit master plan the original MRT Blue Line section was planned to be extended from Hua Lamphong to Lak Song, and from Bang Sue to Tha Phra, forming a circle open-loop route. The contract for the first part of extension to Tao Poon was signed on 26 August 2009^[7] as part of MRT Purple Line contract as it provided interchange to the MRT Purple Line. The 1.2 km (0.75 mi) Bang Sue to Tao Poon extension opened on 11 August 2017.^[8] This added the first elevated station, Tao Poon, to the Blue line.^[9][10]

Extensions to Lak Song and Tha Phra

The major extension of the MRT Blue Line was the 27 km (16.8 mi) extension west to Lak Song and from Tao Poon to Tha Phra with 19 stations consisting of four underground and 15 elevated stations. Contracts for civil work were divided into five contracts. Successful bids were announced in late 2010.^[11][12][13] On 17 February 2011, the five contracts were signed.^[14][15]

Construction commenced in mid-2011 for a scheduled 2016 opening but this was subsequently delayed to 2019–2020. In August, 2017, BEM awarded the automatic fare collection ticket for the extension to Thales which to install its TransCity system.^[16] The contract also includes ongoing training and future support. In September 2017, BEM announced that Siemens and ST Electronics Thailand were awarded the contract (Contract 5) to supply, install and maintain the E&S systems systems, install station platform screen doors and fit out the depot. Siemens also won the contract to supply 35 sets of rolling stock.^[17]

In 2017, the cabinet approved the amendment of the Blue line concession^[18] with BEM, and the new agreement was signed on 31 March 2017.^[19] Under the new agreement, BEM will operate the new extensions from Hua Lampong to Lak Song and Bang Sue to Tha Phra. The concession period was extended from 2029 to 2050.^{[citation needed]}

• Wat Mangkon station under construction. The station opened on 29 July 2019.
• Bang Wa station under construction. The station opened on 29 July 2019.

The extension was opened in stages. The Hua Lamphong - Lak Song extension was opened for trial service on 29 July with full commercial services commencing 29 September 2019.

The Tao Poon - Tha Phra extension opened for limited trial services from 29 November 2019 with full commercial services commencing on 30 March 2020.

First generation

19 three-car Siemens Modular Metro were ordered for the initial part of the line. The trains entered service on 3 July 2004.^[27] In 2017, BEM starts removing some seats from the train to increase interior space to cope with rising number of passengers. In 2019, the BEM stated that it is interested in refurbishing the first generation trains. Including the CCTV cameras, and new dynamic route map replacing the traditional ones.^[28]

• First Generation train of MRT Blue Line (Siemens Modular Metro) or EMU-IBL.
• First Generation train near Tao Poon MRT station.
• Inside a Blue Line train, Siemens Modular Metro.
• Interior of first generation trains. Noted only 1 row of handrails and hanging strap are present and with traditional route map above doors.

Second generation

In 2017, BEM ordered 35 three-car Siemens Modular Metros^[29] as part of the line extension program.^[30][31] Under the contract, Siemens were to supply 35 trains and provide maintenance for ten years with a price tag of 20 billion baht. The fleet was built at the Siemens plant in Vienna and tested in Germany. The first train arrived in 2019 with all trains delivered by early 2020.^[32]

• The second generation train (EMU-BLE) of MRT Blue Line
• Second Generation train at platform level of Bang Wa MRT station
• Interior of second generation trains. With 3 rows of handrails and hanging strap. Along with dynamic route map.
• Dynamic route map on new trains

Ridership

At opening in 2004, initial ridership was 180,000 per day — considerably lower than the projections of over 400,000. By 2016, the average daily ridership was 273,637.^[37] By September 2017, BEM stated that average daily ridership had increased to 360,000 after the opening of the extension to Tao Poon.^[38]

After the opening of the extension to Lak Song on 29 September 2019, average daily ridership increased to 400,000.^[1] The MRT Blue line was expected to grow to a daily ridership of 800,000 once the Lak Song and Tha Phra extensions opened. However, the impact of the COVID-19 pandemic by late 2020 had resulted in a dramatic reduction of ridership down to an average of 360,000 per weekday reverting to September 2017 levels.^[39] By August 2021, during a COVID-19 3rd wave in Bangkok ridership plummeted to only 76,000 per weekday.^[40] In 2023 an average of 376,000 passengers rode the blue line. ^[41]

Train Collision

On 17 January 2005, just after 09:15, an empty train returning to the depot collided with a peak-hour train filled with passengers at the Thailand Cultural Centre station. Around 100-262 people, depending on the news source, were injured.^[42][43][44] Most of whom sustained only minor injuries, and the entire Metro network was shut down for two weeks. On 31 January 2005, then prime minister Thaksin Shinawatra rode the metro to increase public confidence in the system.

After initial investigations, it was found that the empty train had run into problems shortly before the accident, grinding to a halt on a curve leading to the depot. The driver applied its brake and was waiting to be towed to the depot close to Thailand Cultural Centre station. A rescue train was attempting to connect to the stalled train when the driver was told to release the brake while coupling had not yet been successful. It was then that the empty train began to roll backwards at a speed of ten meters per second, before smashing into the other train, which was carrying passengers. Therefore, it was believed that the incident was caused by negligence due to insufficient training of operation staff.^[45] This accident also resulted in two damaged trains with heavily damaged areas limited to the two leading cars. The colliding speed was suspected to be about 60 km/h due to the appearance of damaged areas. However, one train, which was rebuilt from the repair of the minor-damaged cars, was already fitted for operation at the end of 2006 and the remaining one was still under heavy repair until mid of 2007; it was released into service in October 2007. The cost resulting from the accident might be a much higher figure than BEM quoted, and it was expected to be at least 400 million baht, which was totally insured by a local insurance company.^[42]

The line resumed full operations on 1 February 2005. Passenger numbers soon rose back to pre-crash levels, partly due to a temporary promotional fare scheme which allowed passengers to travel any distance on the MRT for only ten baht.