Leaders of the six Greater Mekong Subregion (GMS) countries are expected to endorse a framework of investments worth about US$51.5 billion at a summit in Bangkok this month.
The investments to be discussed from Dec 19-20 will cover 123 projects in 10 sectors, worth a combined $51.3 billion to be carried out over five to 10 years.
They will also consider 92 technical assistance projects costing another $222 million, said Deputy Transport Minister Arkhom Termpittayapaisith, who is also secretary-general of the National Economic and Social Development Board.
On the sidelines of the meeting, Chinese Premier Li Keqiang and Thai Prime Minister Prayut Chan-o-cha will sign a memorandum of understanding for the development of the 867-kilometre double-track railway that links Nong Khai in the Northeast to Map Ta Phut Industrial Estate on the Eastern Seaboard.
Though the bulk of the projects are in transport, other sectors include energy, agriculture, the environment, human resource development, urban development, tourism, trade facilitation and information and communications technology, Mr Arkhom said.
The GMS comprises Cambodia, southern China, Laos, Myanmar, Vietnam and Thailand. With assistance from the Asian Development Bank, it was formed in 1992 to promote economic relations and reduce disparity among member countries.
"Thailand alone will carry out 78 projects, valued at $5.48 billion, equal to 10.6% of the country's budget," he said.
Transport will make up $4.87 billion worth of projects, followed by energy at $282 million, agriculture at $212 million and environmental projects at $158 million.
Other transport projects include construction of a 98-km Bang Yai-Kanchanaburi motorway costing 55.6 billion baht, expansion of a four-lane road from Mae Sot to Tak town and renovation of the Mae Sot checkpoint to support border trade.
Improvements to the East-West Corridor and construction of more bridges spanning the Mekong River are also planned.
Mr Arkhom said leaders would also consider creating a Greater Mekong Railway Association in an attempt to beef up the development of rail system, with the next step extending the Kunming-Vietnam-Cambodia-Thailand-Malaysia-Singapore route.
The summit will also consider setting up a power-generating centre in the region to exchange information or sell power among members, he said.
Japan is also interested in standard gauge railways from Tak-Mukdahan and Chiang Rai-Bangkok, Mr Arkhom added.