TERRATEC EPBMs ready for Bangkok Metro Purple Line


Two new TERRATEC TBMs will take part in Bangkok Metro Purple Line (C3) for Mass Rapid Transit Authority of Thailand.

In December, TERRATEC celebrated the successful Factory Acceptance Test of a new 6.39m diameter Earth Pressure Balance Tunnel Boring Machine (EPBM) which will be deployed for the construction of the Bangkok Metro Purple Line (C3). The event was attended by representatives from the Mass Rapid Transit Authority of Thailand and contractor ITD-NWR MRT Joint Venture. The second Factory Acceptance Test for another EPBM will take place in April 2024.

The two TERRATEC EPBM TBMs will be utilized to construct a total tunnel length of 3.12km, connecting Phan Fa Station to Memorial Bridge Station across two metro stations.

The project encounters several challenges, particularly in navigating the TBMs through the historic area of the old Bangkok capital, which includes landmarks like the Grand Palace and old temple. Another significant aspect is the interchange station at Sam Yod, connecting the Purple Line with the existing Blue Line MRT. The Purple Line will ingeniously pass beneath the operational Blue Line tunnels. Additionally, the TBMs will undergo an impressive feat by driving under the Chao Phraya River for a stretch of 150m. The construction process necessitates meticulous planning and management to ensure minimal disruptions to the surrounding infrastructure and environment.

The geological conditions along the tunnel alignments will encompass soft clay, stiff clay, dense clayey & silty sand. To accommodate these conditions, the TBM’s soft ground cutterhead is equipped with a flat spoke type with copy cutters.

During the construction process, traditionally reinforced, 275mm thick by 1400m wide, Universal reinforced concrete segments (5 + 1) will be installed as the machine progresses. Muck removal, segment transport, and the supply of consumables will be facilitated by rail-bound equipment using battery locomotives.


TERRATEC TBMs feature the Enzan laser guidance system, known as one of the leading systems in the market. This advanced technology allows for remote access to the complete tunnelling system, ensuring accurate control over the TBM operations. With the Enzan system, precise navigation of the tunnels is guaranteed, improving the efficiency and effectiveness of tunnelling projects. Throughout the entire tunnelling operation, TERRATEC’s highly-experienced Field Service staff will provide assistance to ensure optimal performance and successful project completion.

The Bangkok Metro Purple Line, spanning a length of 23.63km and serving the northwestern area of Bangkok from Tao Poon to Klong Bang Phai in Nonthaburi Province, is the fifth rapid transit line. Its southern extension, which comprises a 14.3km underground section and a 9.3km elevated section, commenced construction in August 2022 and includes a total of 17 stations.

TERRATEC has a well-established regional base in Thailand, having sold its first machine in the country more than 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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