Terratec has completed tunnelling works for the Chiang Mai Flood Mitigation Project (Phase 2) in northern Thailand. Commissioned by the Department of Public Works and Town & Country Planning, the project was finalised in early 2025, marking the delivery of a key underground infrastructure system for the region.

This achievement is particularly significant as tunnelling projects of this scale are less common outside Bangkok, said Terratec. The works centred on the construction of a 2.60-m-diameter, 256-m-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 tunnel boring machine (TBM), with reinforced concrete universal tunnel segments forming the lining. Each ring was engineered for both straight and curved alignments, ensuring durability and precision throughout the drive. Rigorous settlement monitoring confirmed ground stability during operations.

The project was delivered by Summit Grade Ltd, Part. (Sam Prasit) in joint effort with SCG 1995 Co Ltd, acting as subcontractor. Both companies worked under the supervision of Panya Consultant Co Ltd, with Terratec providing technical expertise and equipment support.