MRT (Bangkok)

The Metropolitan Rapid Transit or MRT is a medium-capacity rapid transit system serving the Bangkok Metropolitan Region in Thailand. The MRT system comprises two fully operational rapid transit lines (Blue and Purple) and two fully operational monorail lines (Yellow and Pink), with another rapid transit line (Orange) under construction. The MRT Blue Line, officially the Chaloem Ratchamongkhon Line, between Hua Lamphong and Bang Sue was the first to open in July 2004 as Bangkok's second metro system. The MRT Blue line is officially known in Thai as rotfaifa mahanakhon (รถไฟฟ้ามหานคร) or "metropolitan SkyTrain", but it is more commonly called rotfai taidin (รถไฟใต้ดิน), literally, "underground train" as it was distinguished from the BTS Skytrain by being completely underground when its first section between Hua Lamphong to Bang Sue opened.

The second MRT line MRT Purple Line, officially the Chalong Ratchadham Line, opened on 6 August 2016 and connected Tao Poon with Khlong Bang Phai in Nonthaburi in the northwest of Greater Bangkok. It was the first mass transit line to extend outside Bangkok.

Both the Blue Line and Purple Line are operated by the Bangkok Expressway and Metro Public Company Limited (BEM) under a concession granted by the Mass Rapid Transit Authority of Thailand (MRTA), which is the owner of the MRT lines. Along with the BTS Skytrain and the Airport Rail Link, the MRT is part of Bangkok's rail transportation infrastructure. The BEM-operated MRT lines have 526,000 passengers each day as of August 2024 (Blue Line 453,000 and Purple Line 73,000) with 54 operational stations and a combined route length of 71 kilometers (44 mi). Construction began in mid-2011 to extend the MRT Blue Line, after completion in April 2020, the Blue Line has become a quasi loop line (providing interchange with itself at Tha Phra) around the centre of Bangkok.