Following the final groundbreaking of a TERRATEC 6.39m diameter EPBM driven by contractor Italian-Thai Development PCL (ITD) on one of three underground civil works contracts for the first 23km-long (East Section) segment of the Mass Rapid Transit Authority of Thailand’s (MRTA) Orange Line Network, the 3.3km MRT Orange Line (East section) project at Hua Mak Station has been celebrated.
The EPBM started mining eastwards from the Khlong Ban Ma station box on April 26, 2020, after finishing the Westbound tunnel on Jan. 20, 2020, with the best month ever in Thailand with advancement of 663.4m. The TBM was hitting the highest rates of 33 rings every day (46.2m/day – another best every advance rate every day) by mid-June 2020, and had already undertaken its first intermediate breakthrough.
The Westbound tunnel breakthrough on Contract E3 took place a month ahead of time in March 2020. Contract E3’s eastbound tunnel breakthrough was completed 118 days ahead of time.
The TERRATEC S70 TBM was developed to cope with the city’s variable soft ground geology, which involves soft, medium, hard, and very stiff clays, lenses of thick sand, and the likelihood of high-pressure groundwater inflows, as well as the need to mine from various diaphragm wall shafts and possibly concrete piles.
To cope with these demanding conditions, the TBM’s soft field cutterhead has a spoke type and back-loading knife parts to aid shaft break-in and break-out. The unit also has an integrated bentonite face support injection system and a double-gated screw to ensure face stabilization and reduce settlement during excavation in flowin’ areas with sands and high groundwater pressure.
The system has been installing a precast concrete segmental lining consisting of five x 1400mm wide Universal type segments plus main, with an internal diameter of 5.7m, as it travels around the alignment.
TBM tunneling activities for ITD’s Orange Line (East) contract took two years in total.
The new Orange Line in Bangkok would finally be 35.9 kilometers long, with 26.2 kilometers underground and 22 stations and another 9 kilometers and seven stations on elevated structures. In March 2024, the line is expected to open. The Orange Line will provide a critical transit link from Bangkok’s city center to districts in the east when it is completed, eliminating traffic congestion and paving the way for increased mobility, industrial growth, and new residential and commercial opportunities along the alignment.