The move comes after the Cabinet on Tuesday approved MRTA’s borrowing plan for construction of the 23.6-kilometre Tao Poon-Rat Burana section of the line.
The MRTA source said the Public Debt Management Office (PDMO) won a green light from Cabinet to provide a Bt82-billion loan for the construction.
The PDMO will provide the first loan payment worth Bt10.8 billion in June and the MRTA will gradually pay the contractors for six contracts in early July.
The source said the MRTA signed the contracts in March and had now sent notice to proceed on the foundation work in areas requisitioned from government agencies.
The project will expropriate 410 plots of land and 500 buildings. The MRTA is now rushing to carry out surveys of the land and buildings so that the areas can be handed over to the contractors gradually.
The MRTA is concerned that expropriation of land in an Army compound on Nakhon Chaisri Road, Dusit district is a sensitive issue that could affect national security.
The source said the MRTA would have to expropriate a plot in the Royal Thai Army Ordnance School and the Royal Thai Army Ordnance Department for the construction of a tunnel under the compound.
If the expropriation faces delay, the entire project could be delayed, the source added.
The Tao Poon-Rat Burana section of the Purple Line will run underground for 13.6km with 10 stations and feature a 10km elevated section with seven stations.
The project is scheduled to be completed in 2,005 days or about five and a half years, before opening for service in 2027.
The section will begin from Tao Poon elevated station, which will connect with the Chalong Ratchatham and Chalerm Ratchamongkol lines.
The first section will be an elevated railway across the Bang Sue Canal before going underground at the Royal Thai Army Ordnance Department.
The subway will then turn right to Thaharn Road and go under the Kiakkai Intersection to Samsen Road, passing the new Parliament, the Rachinee Bon School, Vajira Hospital and the National Library before turning left.
The subway will then run to Phra Sumeru Road and pass Wat Borworn, Phan Fah Intersection, Rajadamnoen Avenue, Mahachai Road, and reach Chakphet Road before passing under the Chao Phraya River at Phra Pok Klao Bridge.
It will then run to Prajadhipok Road and pass Ban Kaek Intersection, run under Wong Wien Yai roundabout to King Taksin Road and then under the Mahaiswan Intersection where it will become an elevated railway again.
The elevated section will run along Suksawad Road to Pracha Uthit Intersection, Bhumibhol Bridge 1 and Phra Pradaeng Intersection to the terminus at Samut Prakan.