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TERRATEC EPBM completes Bangkok Rama III Cable Tunnel Project
30 April 2022
TERRATEC EPBM completes Bangkok Rama III Cable Tunnel Project

Contractor Italian-Thai Development PCL (ITD) completes multiple TBM projects for Bangkok’s Metropolitan Electricity Authority with the same TERRATEC EPBM.

TERRATEC is proud to announce the completion of the Rama III Tunnel Project in Bangkok, Thailand. The tunnel was completed using a TERRATEC 4.27m diameter Earth Pressure Balance Tunnel Boring Machine (EPBM).  It successfully holed through in early April 2022 on the Rama III cable tunnel in downtown Bangkok.

The EPBM owned by contractor Italian-Thai Development PCL (ITD) had previously completed the Chidlom cable tunnel (CCT).  After completing the CCT the contractor immediately deployed the machine to the Rama III Tunnel Project. 

The Rama III is a new high-voltage cable tunnel which is one of a series of tunnelling projects being undertaken by Bangkok’s Metropolitan Electricity Authority (MEA), which are being built to meet increased power demands in the Thai capital.  

This project is subject to several constraining factors including tight alignment constraints, and navigating the foundations of the overhead bridges along the alignment. This could only be achieved thanks to the X-type articulation system incorporated into the design, which can accommodate the very tight radius curves required by the project of approximately 85m. The TERRATEC 4.27m diameter’s soft ground cutterhead features an open spoke design to ensure good material flow and the addition of knife bits to assist break-in and break-out of the concrete shaft eyes.


Two types of segment were installed, universal tapered precast concrete segments, 1200mm long (installed as the machine normally progresses), and shorter steel segments, 600mm long (utilised during the course of the sharp radius curves).

Tunnelling operations were closely observed throughout the project via a settlement monitoring programme that demonstrated minimal impact on the existing above-ground structures.

Geological conditions along the 3.5 km Rama III tunnel alignment consist of stiff to very stiff clay with lenses of sand and a groundwater head of about 2 bars.

The project is located close to the Chao Phraya River with heavy traffic and the physical limitations of this built-up area – which includes numerous high-rise buildings and the foundation of the overhead bridge. Logistics during the launch and operation of the TBM have been extremely challenging especially during the transportation and delivery of oversize TBM parts for assembly on site. TERRATEC’s highly-experienced Field Service staff have therefore been working closely with ITD from day one in order to ensure every aspect is planned in advance.


TERRATEC has a well-established regional base in Thailand, having sold its first machine in the country ten years ago for the Metropolitan Rapid Transit (MRT) Blue Line Extension Project. With outstanding tailor-made robust TBM design, prompt onsite assistance, readily available stock of TBM spares and specialised TBM support throughout the tunnelling operation, TERRATEC has become the country’s leading TBM supplier.


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