New machines to improve efficiency of MRT2 tunnelling works

GUANGZHOU (Sept 5): MMC-Gamuda KVMRT (T) Sdn Bhd has started the groundwork for the construction of the second Klang Valley mass rapid transit (KVMRT2).

MMC-Gamuda, the project delivery partner, has upgraded four new variable density slurry tunnel boring machines (VD TBMs), which will be used for KVMRT2, in order to improve their operational efficiency.

Dubbed the “VD TBM 2.0”, the 6.6m diameter machines were constructed by German tunnelling expert Herrenknecht AG’s Chinese subsidiary — Guangzhou Herrenknecht Tunnelling Machinery Co Ltd.

The machines cost between RM40 million and RM60 million depending on their specifications, said MRT Corp.

Of the four new TBMs, two will be arriving on Malaysian shores by year end, after having successfully completed their factory acceptance tests (FAT) here last Tuesday, said KVMRT2 contractor MMC-Gamuda’s general manager for tunnelling, Ng Hau Wei.

This is ahead of the commencement of the KVMRT2 tunnelling work, which is slated to start in the first quarter of 2018 for completion by mid-2019.

“Construction is progressing as scheduled and so far, 12.05% of the line has been completed,” MRT Corp director of strategic communications and stakeholder relations Datuk Najmuddin Abdullah told reporters after the FAT at Guangzhou Herrenknecht’s plant.

The entire Sungai Buloh-Serdang-Putrajaya (SSP) line project has a gross development cost of an estimated RM32 billion, according to Najmuddin.

This puts the KVMRT2, also known as the SSP line, on track for the first phase to be launched in July 2021 and the second phase to be launched in 2022, he added.

“23% of the underground works for the SSP line are expected to be completed by this year end, bringing the overall completed works for the line to 19%,” said Najmuddin.

The four new machines will be used to construct the 13.5km underground railway portion of the 52.2km SSP line in addition to the existing eight TBMs which were used for KVMRT1.

“The SSP line has 11 underground stations compared with seven underground stations spanning just 9km for the first Sungai Buloh-Kajang (SBK) line,” Najmuddin said in explaining the need for new machines.

So far, five of the six existing VD TBMs have already been refurbished at the RM100 million TBM refurbishment centre in Pusing, Ipoh, which had been jointly established in collaboration with Herrenknecht AG in Pusing, Ipoh, Ng said.

The remaining two existing TBMs are of the earth pressure balance.

The two new VD TBMs will begin tunnelling near Bandar Malaysia, while the following two VD TBMs, which are expected to arrive from Guangzhou by the end of the first quarter of 2018, will tunnel from Titiwangsa to Jalan Ipoh, according to Blaise Mark Pearce, MRT Corp director of underground works for the SSP line.

The modifications, which will see enhanced wear protection for two of the machines and a higher operating pressure rating for another two, are expected to help improve the VD TBM’s performance in tunnelling through three different ground conditions, namely the Kuala Lumpur limestone formation, granite stone, and the Kenny Hills formation.

More than half of the underground portion of the SSP line will travel through the cavity-riddled karstic limestone formation, for which the VD TBM had initially been developed for the construction of the SBK line.

Modifications to increase its efficiency include upgrading the teeth of the cutter and its angle, as well as improving the arrangement of equipment and pipes within the shield system of the machines in order for more work to be done in the area, Ng said.

The newly modified TBMs will also have to bore through granite stone, for which they have been equipped with a higher crushing capacity and bigger compressed airlock in order to allow workers to perform smoother cutter head interventions, he added.

As a result of the modifications, the likelihood of sinkholes and road damages during the construction of underground portion of the SSP line is expected to be further reduced from the 0.3km of sinkholes seen during the construction of KVMRT1, MRT’s Najmuddin said.

This article first appeared in The Edge Financial Daily, on Sept 5, 2017.

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