The MRT underground train system (officially called MRT - Mass Rapid transit) reaches from the Northern train station of Bangsue to Hua Lumphong main railway station in a loop, connecting with the Skytrain on 3 different stations, namely : Silom, Sukhumvit and Chatuchak Park.
There have a similar ticket system as the Skytrain (BTS) but both systems are for the time being not compatible. All stations of the underground train can be reached via ramps and elevators, if needed, or alternatively via escalators.