The MRTA is concerned that land expropriation at an army compound on Nakhon Chaisri Road, Dusit district is a sensitive issue that could affect national security.
The source said that the MRTA should expropriate land from the Royal Thai Army Ammunition School and the Royal Thai Army Ammunition Department for the construction of a tunnel under the compound.
If the expropriation is delayed, the whole project could be delayed, the source added.
The Tao Poon-Rat Burana section of the Purple Line will be 13.6 km underground with 10 stations and will feature a 10 km elevated section with seven stations.
The project is expected to be completed in 2,005 days or about five and a half years, before commissioning in 2027.
The section will start from Tao Poon elevated station, which will connect to the Chalong Ratchatham and Chalerm Ratchamongkol lines.
The first section will be an elevated railway crossing the Bang Sue Canal before going underground to the Royal Thai Army Ordnance Department.
The metro will then turn right onto Thaharn Road and pass under the Kiakkai intersection to Samsen Road, passing the New Parliament Building, Rachinee Bon School, Vajira Hospital and the National Library before turning left.
The metro will then head towards Phra Sumeru Road and pass through Wat Borworn, Phan Fah Intersection, Rajadamnoen Avenue, Mahachai Road and reach Chakphet Road before crossing under the Chao Phraya River at Phra Pok Klao Bridge.
It will then head to Prajadhipok Road and pass Ban Kaek intersection, pass under Wong Wien Yai roundabout to King Taksin Road, then under Mahaiswan intersection where it will again become an elevated railway.
The elevated section will run along Suksawad Road to Pracha Uthit Junction, Bhumibhol 1 Bridge and Phra Pradaeng Junction to the terminus at Samut Prakan.