Mass Rapid Transit Master Plan in Bangkok Metropolitan Region

The Mass Rapid Transit Master Plan in Bangkok Metropolitan Region, or M-Map, is the latest version in a series of Thai government plans for the development of an urban rail transit network serving the Greater Bangkok area. It was drafted under the care of the Office of Transport and Traffic Policy and Planning (OTP) of the Ministry of Transport.

Lavalin Skytrain project
Lavalin Skytrain Project is the earliest mass rapid transit plan of Bangkok to solve the traffic congestion in Bangkok during 1970s. The project feasibility study was conducted by Thai Government with the association from West Germany Government in 1971 which led to establishment of Expressway Authority of Thailand under Clause 39 of the Announcement of the Revolutionary Council Decree 290 dated 27 November 1972 (B.E.2515) to responsible for planning and construction of expressway and mass rapid transit projects.

In 1979, the master plan compiled by Japanese advisers would have consisted of the First Stage Urban Mass Transit Lines such as the first line known as the Rama IV line, a 25-km route between Phrakhanong and Mo Chit, while the second line, the Sathron line, a 20-km route would connect Wongwian Yai and Lad Phrao, and the third line, the Memorial Line, a 16-km route that connects Dao Khanong and Makkasan, and the expected numbers of passengers were expected to be 200,000 passengers a day in 1990. The rolling stock would have utilized six heavy rail cars running at 15 minutes per train for non-rush hour and four minutes during rush hour, compared with current trains running at 6–8 minutes per train during non-rush hour and 3-5 minutes per train during rush hour, using three heavy rail cars. The project was meant to have a cost of $1100 million.

The finalised version of the project consisted of three light rail transit lines which are Sathorn Line, Rama IV Line, and Saphan Phut Line, with the depot located in Huai Khwang district (current location of Phra Ram 9 depot of MRT Blue Line). The project was expected to begin in 1981 and be completed in 1986. However, due to the 1979 oil crisis, Lavalin Skytrain project was shelved as the estimated costs were doubled.

The project was revised under the government of General Prem Tinsulanonda in 1984 and entered the bidding process with three participating companies being Asia-Euro Consortium (comprising AEG, Siemens, MAN, and Ateliers de Constructions Electriques de Charleroi), SNC-Lavalin, and Franco-Japanese Consortium. The project was awarded to SNC-Lavalin, and the contracts for a 30-year operating concession and construction were signed in May 1990 at Queen Sirikit National Convention Centre.

However, after two years of construction, In June 1992, The project was terminated by the government of Anand Panyarachun. The government stated that SNC-Lavalin failed to sign a shareholders agreement by a specified and the Thai government refused requests for overseas loan and investment guarantees. Outside of Thailand, numerous international media sources suggested politics played in its demise. Today, There are two remainings from the construction of Lavalin Skytrain project: the abandoned viaduct in the middle of Phra Pok Klao Bridge (now converted into Chao Phraya Skypark), and a reserved space in the middle of Sathorn Bridge (currently used by Silom Line).

Mass Rapid Transit Systems Master Plan (MTMP)
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 km 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 km.

Urban Rail Transportation Master Plan in Bangkok and Surrounding Areas (URMAP)
Following the 1997 Asian Financial Crisis and the cancellation of the BERTS, a system totalling 375 km to begin in 2001 was proposed, to be developed in three stages: 141.9 km during 2001–11, 158.2 km during 2012–21 and 75.3 km from 2022 onwards.

Bangkok Mass Transit Master Plan (BMT)
Due to the slow progress of development following URMAP, a new plan was drafted consisting of 475.05 km 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 construction
 *  Orange Line: Running east–west Min Buri to Bang Khun Non
 *  SRT Dark Red Line: Running north–southwest from Rangsit to Krung Thep Aphiwat to Maha Chai
 *  SRT Light Red Line: running east–west from Hua Mak to Sala Ya
 * Airport Rail Link: North extension to Don Mueang

Original M-Map (2010)
The first M-Map plan was endorsed by the Commission for the Management of Land Traffic in 2010. It designated eight primary routes, consisting of two commuter rail lines, an airport rail link, and five rapid transit lines, as well as five feeder lines. The routes, totaling 555.74 km, were to be constructed within a development period of twenty years (2010–29). They were:

Development would be divided into three stages, in addition to those lines already open or under construction.

M-Map 2 (2017)
The 2010 M-Map did not reflect more recent changes to the priority of constructing new rapid transit lines in Bangkok. While the Orange, Yellow and Pink lines received approval in the years that followed, the Grey and Light Blue lines remained unapproved at the time of the next M-Map. In March 2017, the Minister of Transport announced the development of the Second Mass Rapid Transit Master Plan in Bangkok Metropolitan Region (M-Map 2). The Office of Transport and Traffic Policy and Planning (OTP) was the main agency responsible for this master plan's development, with technical assistance from the Japan International Cooperation Agency (JICA).

The initial project materials listed the following lines as part of the plan:

In 2019, JICA released a Proposed M-MAP2 Blueprint study, outlining "key policy directions and measures based on which the M-MAP2 will be developed by the Thai Government". The Department of Rail Transport, OTP's successor agency for rail transport planning, is in the process of completing M-Map 2.

Lines outside of M-Map 2
, the Grey and Light Blue line projects remain unapproved; however, the MRT Brown Line project, which will link Nonthaburi Civic Center with the Lam Sali intersection between Ramkhamhaeng and Srinagarindra roads, has gained cabinet approval. Additionally, a Gold Line along Charoen Nakhon road that starts at Krung Thonburi, partially funded by property developer Siam Piwat, has been operational outside of the M-Map framework since 2020 and is planned to be further extended towards the Memorial Bridge, linking it with the Purple Line extension that runs through the bridge's surrounding area.