By Lynda Myer
In order to construting the Bangkok Metro Purple Line (C3), a new 6.39m diameter Earth Pressure Balance Tunnel Boring Machine (EPBM) is due to be used which’s successful Factory Acceptance Test was celebrated by TERRATEC in December 2023. The event was attended by representatives from the Mass Rapid Transit Authority of Thailand and contractor ITD-NWR MRT Joint Venture. The scheduled date for second Factory Acceptance Test for another EPBM is April 2024.
Linking Phan Fa Station to Memorial Bridge Station across two metro stations, the tunnel with total length of 3.12km will be built using thease two TERRATEC EPBM TBMs.
While one of the challanges of this project in its path will be in navigating the TBMs through the historic area of the old Bangkok capital, which includes landmarks like the Grand Palace and old temple, the interchange station at Sam Yod, connecting the Purple Line with the existing Blue Line MRT, will be the other significant aspect. The passing route of Purple Line is ingeniously slated to be 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.
Considering that the geological conditions along the tunnel alignments will encompass soft clay, stiff clay, dense clayey & silty sand, the TBM’s soft ground cutterhead is equipped with a flat spoke type with copy cutters to accommodate these conditions.
Over advancement of the machine and during the construction process, traditionally reinforced, 275mm thick by 1400m wide, Universal reinforced concrete segments (5 + 1) are due to be installed. Muck removal, segment transport, and the supply of consumables will be facilitated by rail-bound equipment using battery locomotives.
Additionally, remote access to the complete tunneling system, as well as ensuring accurate control over the TBM operations, will be done using the Enzan laser guidance system of TERRATEC TBMs that is known as one of the leading systems in the market. 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.
As the fifth rapid transit line, the Bangkok Metro Purple Line is 23.63km long and servs the northwestern area of Bangkok from Tao Poon to Klong Bang Phai in Nonthaburi Province. The construction process of its southern extension, which comprises a 14.3km underground section and a 9.3km elevated section, was commenced 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.
