High Quality Content by WIKIPEDIA articles! The Metropolitan Rapid Transit or MRT is a rapid transit system serving the Bangkok Metropolitan Region in Thailand. The first section of the Blue Line between Hua Lamphong and Bang Sue opened in 2004 as Bangkok`s second public transit system. The MRT is operated by the Bangkok Metro Public Company Limited (BMPCL) under a concession granted by the Mass Rapid Transit Authority of Thailand (MRTA). Along with the Bangkok Mass Transit System (BTS, also called the Skytrain), and the Airport Rail Link (ARL), the MRT is part of Bangkok`s rail transportation infrastructure.