The Japanese Empire built the infamous Thailand–Burma railway using prisoners of war to connect Bangkok and Yangon, but the entire line never entered commercial operation and is now partially submerged by the reservoir behind the Vajiralongkorn Dam.

[9] In 2000, ASEAN proposed completing the Kunming to Singapore railway, via Hanoi, Ho Chi Minh City (formerly Saigon), Phnom Penh, and Bangkok.

In 2004, ASEAN and China proposed the shorter western route, which instead of running east through Vietnam and Cambodia, would go west from Kunming to Myanmar and then to Bangkok.

[23][24] The central route consists of the following sections: This line was originally planned as a high-speed rail joint-venture between the Laotian government and the China Railway Corporation, the Chinese state rail operator, and set to begin construction on 25 April 2011 but was delayed due to a corruption scandal that removed the Chinese railway minister, Liu Zhijun from office.

[40] A year later in August 2012, the Thai government announced the plans to build four high-speed rail lines, including extensions to Nong Khai and Hat Yai by 2022.

[43] The opposition Democratic Party challenged the spending bill in court and a judge expressed doubt about the necessity of high-speed rail for Thailand.

[44] The ensuing political protests in Bangkok, which began in December 2013 and continued through May 2014, has paralyzed the Thai government and prevented further decision-making of the rail project.

On 30 July 2014, Thai army chief General Prayut Chan-o-cha, whose forces seized control of the government through a bloodless coup in May, announced plans to build two high-speed rail lines as part of a 741.4 billion baht transportation program.

[45] The Nong Khai to Map Ta Phut line, 737 kilometres (458 mi) in length, would run from the Laotian border at Thanaleng to the Gulf of Thailand.

[46] On 4 December 2014, the Thai National Legislative Assembly voted 187–0 with seven abstentions to approve loans for the Nong Khai-Map Ta Phut and Kaeng Khoi-Bangkok lines.

[26] In March 2020, the Thai government committed to a US$21 billion railway expansion plan that will include a high speed rail from China to Singapore through Bangkok via the Laotian border near Vientiane.

[52] But in March 2011, the Chinese Commerce Minister Chen Deming stated that the project was delayed due to the first elections in Myanmar in 20 years and differences in the railway gauge of the two countries.

[53] He explained the Chinese rail developers were waiting for the new cabinet in Myanmar to form and expressed hope that work on the line would begin before the end of 2011.

[57][58] According to PLANMalaysia, a northern high-speed rail corridor will be built along North-South Expressway and the stations will be at Tanjung Malim, Tapah, Ipoh, Taiping and terminated at Butterworth.

[60][61] Among revisions being explored to reduce costs, was to align the route to the existing meter gauge Keretapi Tanah Melayu (KTM) line and lay a standard gauge track in parallel, with a fork running to Jurong East so that bilateral agreement is not violated, to allow trains running at 200 km/h, cutting journey time between Kuala Lumpur and Singapore to 130 minutes.

[62] Stations were planned for Bandar Malaysia in Kuala Lumpur, Bangi-Putrajaya, Labu (Seremban), Muar, Batu Pahat, Iskandar Puteri and Jurong East.