First VFD breakthrough

The breakthrough marks the completion of the first section of twin tunnels between Cochrane and Pasar Rakyat Station for the 9.5km Sungai Buloh-Kajang Line, part of MRT's project to construct a new rail transport system for the Klang Valley, Kuala Lumpur.

The variable density TBM is the first of its kind, designed and jointly developed by the MRT project¹s underground works contractor, MMC Gamuda KVMRT (T) Sdn Bhd and Herrenknecht, specifically for tunnelling beneath Kuala Lumpur.

Kuala Lumpur is built above two different geological formations. In the western part of the city is the Kenny Hill Formation, which is more consistent and easier to tunnel through. In the eastern part lies the Kuala Lumpur Limestone geological formation, which consists of hard rock with soft overlaying, as well as void chambers and cavities that cannot be easily identified.

The TBM is designed to handle excavation through the transition between the two geological formations, as well as to overcome the challenges posed by tunnelling through the karstic nature of the Kuala Lumpur limestone formation, MRT stated.

Encik Haris Fadzilah Hasan, MRT's acting CEO, said: "Within seven months of Prime Minister Dato¹ Sri Mohd Najib Tun Abdul Razak launching the first TBM, we have completed the first section of tunnels. I am confident that we will be able to complete constructing the entire length of tunnels by mid-2015, according to the programme."

The breakthrough follows an earlier one that took place at the KL Sentral MRT Station worksite on 24 December 2013. That machine, Semantan 1, was a EPB machine and will be re-launched to excavate through to Pasar Seni Station.

A total of 10 TBMs will be used for the construction of tunnels for the 9.5km underground portion of the Sungai Buloh-Kajang Line. Four EPB machines and six variable density TBMs will be used. With the completion of Cochrane 2, six TBMs are in operation at various stages of tunnelling for the project.