1. Bangkok’s Sukhumvit Line, also known as the Green Line, was extended by the Mass Rapid Transit Authority of Thailand (MRTA). Image courtesy of Ilya Plekhanov via Wikipedia.
The existing Green Line between Mo Chit and Bearing was extended in both directions. Image courtesy of Globe-trotter via Wikipedia.
The Green Line, in its southern expansion, was extended by 12.6km from the Bearing station to Samutprakarn. Image courtesy of Leisure / Kakiko via Wikipedia.

Mass Rapid Transit Authority of Thailand (MRTA) is expanding Bangkok’s Green Line in two directions. The existing Green Line, also known as the Sukhumvit Line, is an elevated rail line from Mo Chit in the Chatuchak District to Bearing in Bang Na District of Bangkok.

In the southern expansion, the Green Line was extended from Bearing to Samutprakarn. The northern expansion included the extension of the line from Mo Chit to Khu Khot, via Saphan Mai.

The southern extension of the Green Line was opened for service in December 2018, followed by the northern extension in December 2020.

Route details of the existing Green Line

The existing Green Line is one of the two lines of the Bangkok Skytrain transit system operated by Bangkok Mass Transit System Public Company (BTSC). The two Bangkok Skytrain lines, namely Sukhumvit Line and Silom Line, interchange at the Siam Station. The 22.25km Sukhumvit line, also known as the Green Line, extends from Siam Station in a northward direction to Mo Chit and an eastward direction to Bearing.

The Green Line originally consisted of 17 stations from Mo Chit to On Nut when it was first opened in 1999. The rapid transit line was extended by 5.25km from On Nut (E9) to Bearing in August 2011. Five new stations were built as part of the extension. The extension, funded by the Bangkok Metropolitan Administration (BMA), was contracted to BTSC for operation.

MRT Green Line extension project background

The Thai Cabinet approved the development of mass rapid transit systems in Bangkok in November 2006, which also included the extension of the existing Green Line. The feasibility study for the Bearing-Samutprakarn section of the Green Line extension was completed by December 2007.

In November 2008, MRTA was authorised by the cabinet to operate the Bearing-Samutprakarn, as well as the Mo Chit-Saphan Mai section of the Green Line extension. Approval for extending the Green Line further from Saphan Mai to Khu Khot was received in February 2010.

Details of Bearing-Samutprakarn section of Green Line extension

The 12.6km elevated line from Bearing to Samutprakarn involved the construction of nine new stations along the route. The stations are designed to stand along the median of Sukhumvit road with a few of them integrated with other mass transit lines.

A 48-acre depot capable of housing 40 three-car trains were built at the ending point of the route near Bang Pu. The Operation Control Centre (OCC) and administration buildings for the project were also located in the depot area.

The Bearing-Samutprakarn extension line can serve up to 57,000 passengers a day. Preliminary construction works of the project were started in 2012 and the extension was completed at a cost of THB24.54bn ($763.5m).

Mo Chit-Khu Khot Green Line extension

A total of 16 stations were built for the Mo Chit-Khu Khot section of the MRT Green Line extension. The depot housing 36 trains and the OCC is built near Khu Khot station.

The Mo Chit-Khu Khot Green Line MRT project required a cost of THB52.97bn ($1.6bn).

Rolling stock for the Bangkok MRT Green line extension

Both sections of the Green Line extension are operated with 750V DC rolling stock with three to six cars.

The recently launched four-car metro trains operate on the existing BTS (Skytrain) system and the Green Line extensions and further improve the capacity of the tracks to more than one million passengers a day.

These trains have a maximum speed of 80km/h and can accommodate 112 seats and 1,460 standing capacity at crush loading.

The first metro car out of 22 new four-car trains for Green Line extension was delivered to Thailand in August 2018. The last train entered service in October 2019.

Contractors involved with Bangkok MRT Green Line Extension

Ch. Karnchang Public Company of Thailand was awarded a $74.6m contract in April 2013 for track laying and electrical systems for the Bearing-Samutprakarn section of the Green Line extension.

Alstom was awarded a €14m ($18.4m) contract by Ch. Karnchang in September 2013 towards the design-build of track work and the third rail power collector for the new extension.

In addition to the trains, Siemens also provides the rail electrification system for this extension of the Green Line.