The Mass Rapid Transit Authority (MRTA) in Thailand prepares a tender to invite interested companies for the Purple Line extension PPP project, an electric rail line to connect Tao Poon and Rat Burana in Bangkok.

The international bidding process allows purchasing bid envelopes until December 24, 2021. The decision to start the bidding process comes after the MRTA's assessment of the public opinion on the project, as well as recommendations from the Comptroller General's Department. The project has an estimated value of THB78 billion (US$2.37 billion).

The project will extend the Purple Line by 23 kilometers. The work will be divided into six phases: the first one extends the line by 4.8 km with 3 new stations, the second phase includes 2.3 km of the new rail line with 3 stations, the phase 3 will see additional 3 new stations, while the fourth and fifth phases will extend the line to Dao Khanong and Khru Nai. The last sixth phase includes mainly the railway signaling system. Once operational in 2027, the Purple Line will connect Nonthaburi and Samut Prakan, via Thon Buri and Phra Nakhon districts.