Additional 1-metre-wide railways will be laid parallel to existing lines on crowded routes, according to Prayuth Chan-ocha, chief of the National Council for Peace and Order (NCPO).
Thailand's rail system is one metre wide, supporting up to 90km/h.
A double-track railway usually involves running one track in each direction, compared to a single-track railway where trains in both directions share the same track.
The project, likely to be the first to be implemented in October, was aimed at making the best use of the existing lines and save state budgets while avoiding costing the country many trade and transport opportunities, Gen Prayuth said in a televised address at 8.30pm today.
The enhanced lines, already put in place by the Transport Ministry, will support more loads and reduce logistic costs.
The five routes are, in order of priority: Chachoengsao-Khlong Sib Kao-Kaeng Khoi (Saraburi), Lop Buri-Pak Nam Pho (Nakhon Sawan), Map Kabao (Saraburi)-Thanon Chira Junction (Nakhon Ratchasima), Nakhon Pathom-Nong Pla Duk junction (Ratchaburi)-Hua Hin and Prachuap Khiri Khan-Chumphon
ACM Prajin Juntong, one of his deputies, was assigned to prioritise infrastructure projects so construction can begin in October this year, starting with those with the most readiness.
In prioritising dual-gauge rail track upgrades, the main criterion is connectivity with other Southeast Asian countries and China.
New technology will be used with a standard gauge of 1.435 metres wide to support train speeds of 160-180 kilometres per hour.
Junctions and links, as well as tunnels, will also have to be improved to prevent bottlenecks.
As for water management to prevent devastating floods, a budget of 13 billion baht will be allocated from ministries' existing 2014 budgets.
It will be used to rehabilitate water sources and dredging to improve reserving and discharging efficiencies.
Simultaneously, a three-phase roadmap will be implemented.
The first phase involves preparations and planning, which should be completed this month.
In the second phase, detailed work plans for each projects will be prepared within 45 days.
The last phase involves a complete plan for water management which will be finished by October.
Gen Prayuth also defended the NCPO's decision to revamp the police force by giving a seat on the powerful National Police Policy Commission (NPPC) to the permanent secretary for defence and dumped two of the three seats reserved for politicians.
“The NCPO will not interfere in any appointment and leave the issue to the National Police Office,’’ he said.
The NCPO announced the restructuring of the NPPC and the Police Commission on Monday. The NPPC is responsible for a search for a new police chief and the lower-ranking Police Commission is responsible for promoting senior police officers.
The military regime dropped two seats formerly reserved for the interior and justice ministers from the NPPC in a move to curb political influence in the selection of a police chief. Candidates for a new police commander will be nominated by the present police chief instead of the prime minister, who still chairs the panel.
The army chief said the restructured commissions were only temporary for the dignity of the organisation, gave an opportunity for qualified officers and ended cronyism.
"The NCPO pays special attention to security agencies with no desire to damage the dignity and reputation and dismantle the police force,’’ he added.
The position of the police chief was left vacant after the junta moved Adul Saengsingkaew from the agency to take charge of special affairs at Government House. Pol Gen Adul still keeps another post as a deputy NCPO chairman.
Deputy police commander Pol Gen Watcharapol Prasarnratchakij is the acting police chief.
Pol Gen Adul will retire at the end of September.