Thailand's Transportation Ministry is preparing a 20-year plan to upgrade the state railway system involving an investment of $29.9bn (THB1tr).
The plan is to improve the railway system to meet international standards, with work planned to be carried out over three phases until 2029.
The first three-year stage will involve replacing the old train engine cars and improving signalling systems across the network.
The second phase from 2011 to 2020 involves converting the existing single-track lines to dual-track lines.
The third phase from 2020 to 2029 involves work on four high-speed train routes.
The proposal will be submitted to the cabinet for approval shortly, the ministry said.