TBM is launching from the tunnel shaft.

The Bangkok Metropolitan Rapid Transit Authority (MRTA) was established to implement the Mass Transit Master Plan consisting of a 80km rail network. The aim was to provide the people of Bangkok with a fast, affordable and environmentally-sound transport alternative to motor vehicles and buses, thereby helping to alleviate the chronic traffic congestion in metropolitan Bangkok.

The Initial System Project (ISP), or Blue Line, at 20km long is the first link in the network, commencing at the current central railway station of Hua Lampohong, running under major arterial roads and linking up to the hub bus/rail interchange at Mo Chit and the suburban SRT station at Bang Sue.

The ISP is a conventional heavy-rail Mass Transit System, totally underground except for the Depot and approaches to the Depot. The horizontal alignment follows the existing roadways, while the vertical alignment ranges from 14 to 30 metres below ground level. The line will consist of twin, single track tunnels, each with an internal diameter of approximately 5.7 metres, and with a concrete segment lining. There are 18 stations located approximately one kilometre apart and a "Park and Ride" building.

The ISP is to be constructed in two sections and the ION Joint Venture (Italian-Thai Development Public Co., Ltd., Obayashi Corporation, Nishimatsu Construction Co., Ltd.) commenced work on the north section in August, 1997. Nishimatsu will construct three stations, 8.8km of bored tunnel (in conjunction with Italian-Thai) and 1.1km of Cut and Cover tunnel.