Mass Rapid Transit Master Plan in Bangkok Metropolitan Region

The first version of the plan, endorsed by the cabinet on 27 September 1994 and to be implemented from 1995 to 2011, consisted of an extension of 135 kilometres (84 mi) to the three systems already in progress (the MRT Blue Line, the Sukhumvit and Silom lines of the BTS Skytrain and the Bangkok Elevated Road and Train System (BERTS)), which would have had a combined length of 103 kilometres (64 mi).[1]

Following the 1997 Asian Financial Crisis and the cancellation of the BERTS, a system totalling 375 kilometres (233 mi) to begin in 2001 was proposed, to be developed in three stages: 141.9 kilometres (88.2 mi) during 2001–11, 158.2 kilometres (98.3 mi) during 2012–21 and 75.3 kilometres (46.8 mi) from 2022 onwards.[1]

Due to the slow progress of development following URMAP, a new plan was drafted consisting of 475.05 kilometres (295.18 mi) of rail in addition to the then-completed MRT Blue Line, the Sukhumvit and Silom BTS lines, the MRT purple line, and the Airport Rail Link to undergo rapid development during 2010–29. The plan was approved by the cabinet in 2016, and consisted of the following extensions:

•     Light Green Line: North–south extension of the BTS to Khu Khot and Kheha Samut Prakan
•     Dark Green Line: West extension of the BTS to Yot Se
•     Blue Line: Extension of the MRT Blue Line to complete a quasi circle line with a branch to Lak Song
•     Purple Line: South extension to Rat Burana is under study
•     Orange Line: Running east–west Min Buri to Bang Khun Non
•     SRT Dark Red Line: Running north–southwest from Rangsit to Bang Sue to Maha Chai
•     SRT Light Red Line: running east–west from Hua Mak to Sala Ya
•     Airport Rail Link: North extension to Don Mueang

The 2010 M-Map did not reflect more recent changes to the priority of constructing new rapid transit lines in Bangkok. While the Orange, Pink and Yellow lines received approval, the Grey Line and Light Blue lines are still under study. In March 2017 the Minister of Transport announced the development of M-Map 2[5] to be written by the Office of Transport and Traffic Policy and Planning in conjunction with the Japan International Cooperation Agency. The initial map listed the following lines in the current plan:[6]

The Grey and Light Blue line remain under study. The MRT Brown Line which will link Nonthaburi Civic Center with the Lam Sali Intersection has been approved.

Additionally, a Gold Line from Krung Thonburi – Memorial Bridge, partially funded by property developer Siam Piwat is under construction outside of the M-Map framework.