The project, commissioned by the Department of Public Works and Town & Country Planning, was finalised earlier this year.
Terratec, which supplied the TBM for the project, said the tunnelling achievement was particularly significant as tunnelling projects of this scale were less common outside Bangkok.
The works centred on the construction of a 2.6m-diameter, 256m-long drainage tunnel, designed to integrate with Chiang Mai’s existing stormwater network. In addition to the tunnel drive, the scope included launching and reception shafts, steel pipe connections, HDPE pipeline installation, hydraulic structures, and surface drainage channels.
The tunnel was excavated using a Terratec TBM, with reinforced concrete Universal Tunnel Segments forming the lining. Each ring was engineered for both straight and curved alignments to provide durability and precision throughout the drive.
The project, which strengthens the city’s flood resilience, was delivered by Summit Grade Ltd, Part. (Sam Prasit), with subcontractor SCG 1995 Co Ltd. Both companies worked under the supervision of Panya Consultant Co Ltd, and Terratec provided technical expertise and equipment support.
