Early completion for Bangkok Metro drive 08 Apr 2021

A Terratec 6.39m EPBM has completed the 3.3km eastbound drive for the Bangkok Metro Orange Line four months early. Operated by Italian contractor Italian-Thai Development (ITD), the TBM broke through at Hua Mak Station, one of three underground civil works contracts for the 23km long east section of new metro line for the Mass Rapid Transit Authority of Thailand (MRTA).

Breakthrough at Hua Mak Station

Early breakthrough celebrations

Contract E3, which was awarded to ITD in May 2017, totals more than 6km of TBM driven tunnel and three underground stations, extending from Khlong Ban Ma to Hua Mak. After completing the westbound tunnel on Jan 20, 2020 with progress of 663.4m in one month and a month ahead of schedule, the EPBM started excavating eastwards from the Khlong Ban Ma station box on April 26, 2020, and quickly got up to speed following its initial drive. By mid-June 2020, the TBM was achieving the best rates of 33 rings (46.2m) per day and had already undertaken its first intermediate breakthrough.

The Terratec EPBM was designed to tackle the variable soft ground geology of the city which ranges from soft and medium to stiff and very stiff clays, with lenses of dense sand and the potential for high pressure groundwater inflows, as well as the need to excavate through numerous diaphragm wall shafts and potentially, concrete piles.

In order to handle these challenging conditions, the TBM soft ground cutterhead features a spoke style and the addition of back loading knife bits to assist the break-in and break-out of the shafts. In addition, the machine is fitted with an active bentonite face support injection system and double gated screw, to ensure face stability and mitigate settlement during excavation in areas of flowing sands and high groundwater pressure.

Terratec EPBM completes Bangkok Metro line drive

As the machine progresses along the alignment, it has been installing a precast concrete segmental lining consisting of five x 1.4m wide universal style segments plus key, with a 5.7m i.d. The segments are being produced by ITD at the same factory used for segment manufacture during its MRT Blue Line underground works contract five years ago, which also employed a Terratec TBM.

When complete, the Bangkok new Orange Line will total 35.9km with 26.2km aligned underground with 22 underground stations a further 9km and seven stations on elevated structures. The line is scheduled to open in March 2024. The Orange Line will provide a vital transportation link from Bangkok city centre to districts in the east, reducing traffic congestion and paving the way for improved accessibility, economic growth and new residential and commercial opportunities along the alignment.