Inaugurated on 5th December 1999, the BTS SkyTrain was the first electric mass transit railway system to commence operations in Thailand. Built and operated by the Bangkok Mass Transit System Public Company Limited (BTSC), the project was entirely funded by private enterprise. The BTS SkyTrain operates on two lines: The Sukhumvit Line, royally bestowed with the title 'Elevated Train in Commemoration of His Majesty the King's 6th Cycle Birthday, Route 1 (Sukhumvit Line), running 17 kilometers and on 12th August 2011, a 5.25 kilometer extension of the Sukhumvit Line commenced operations, expand in train services from On Nut to Bearing Station.
The Elevated Train in Commemoration of His Majesty the King's 6th Cycle Birthday, Route 2 (Silom Line) running 6.5 kilometers was officially inaugurated on 5th December 1999. Subsequently on 23rd August 2009, a 2.2 kilometer extension of the Silom Line commenced operations, expanding train services from Saphan Taksin to Wongwian Yai station on Thonburi side of the Chaophraya River. On 14th February 2013, a further 2.17 kilometer extension of the Silom Line commenced operations to Pho Nimit and Talat Phlu stations. Finally, On 5th December 2013, a further 3.8 kilometer extension of the Silom Line commenced operations to Wutthakat and Bang Wa stations. From April 3rd 2017 onwards, the company offered free trips for passengers on the Green Line Extension, between Bearing and Samrong Stations. The travel distance on this extension is about 1.8 kilometers. Recently, on 6th December 2018, a further extension of the Green Line was opened consisting of 9 new stations: Samrong, Pu Chao, Chang Erawan, Royal Thai Naval Academy, Pak Nam, Srinagarindra, Phraek Sa, Sai Luat and Keha. The travel distance on this new extension is 11 kilometers, On 9th August 2019, a further extension of the Green Line was opened new stations; Ha Yaek Lat Phrao . and On 4th December 2019 , there are 4 more stations to Kasetsart university station .The travel distance on this new extension make a combined total length on the Green Line of 54.12 kilometers, connecting 48 stations.
The BTS SkyTrain system is a standard mass transit system commonly used in cosmopolitan cities. The SkyTrain runs on an elevated track, using a third-rail system to supply electricity, with in-bound and out-bound trains running on separate tracks and platforms. The BTS SkyTrain changes the face of the urban commute and raises the standard of mass transit services with each train serving up to 1,000 passengers per journey compared to the 250 vehicles on the roads transporting the same number of commuters.
In addition to serving businesses, shopping districts and residential areas in the heart of Bangkok, an extension project is also in the plan in order to reach the broader community of potential passengers in suburban Bangkok.