The MRT Purple Line is a subway line of the Bangkok Mass Transit System that is presently under construction. It will run from the northeastern part of Bangkok in Nonthaburi Province to the southern area of Thonburi in Rat Burana district. It will pass through downtown Bangkok, including Rattanakosin, Dusit and Phra Nakhon, which until now are not served by any rapid transit lines.
The MRT Purple Line is being constructed under two phases. Phase One involves the section from the Tao Pun MRT Station to the Rat Burana MRT Station. It is 23 km in length and is forecasted to be operational in 2014. Phase Two involves the section from Tao Pun MRT Station to Khlong Bang Phai MRT Station. It is 19.8 km long and is forecasted to be operational by 2019.