TUNNELLING works for the MRT Sungai Buloh-Serdang-Putrajaya (SSP) Line in Kuala Lumpur is currently in progress.
Over the next two weeks, the Variable Density Tunnel Boring Machine (TBM) will be traversing below Jalan Sungai Besi – the main gateway that connects to the city centre and other suburbs in Kuala Lumpur.
The current section being mined consists mainly of weathered limestone formations.
Weathered limestone is a geological formation known for its complexity and intrinsic challenges to TBM operations.
This complexity could possibly lead to above-ground sinkholes, which would inadvertently result in unplanned road closures.
“While the TBM is equipped for the challenging terrain, further measures have been taken to safeguard the public from any untoward incident,” said Gamuda Engineering Managing Director Datuk Ubull Din Om.
“One preventive measure is ground treatment, which is done progressively ahead of the TBM’s arrival where the ground investigation shows anomalies.”
Ground treatment involves pumping significant amounts of concrete/mortar into targeted areas underground to strengthen the ground before mining.
This would give the TBM greater stability as it mines against solid blocks of concrete instead of the natural karstic elements of weathered limestone which can be unpredictable and unfavourable to mining operations.
However, not all areas along the TBM travel paths are accessible for ground treatment works, hence giving rise to hidden risks.
“Apart from more intensive monitoring of the TBM as it makes its way through these highly sensitive zones, a team has been put together for on-ground monitoring 24/7.
“Known as the ‘bull gang’, the team comprises personnel who are constantly on the lookout for the smallest of inconsistencies on the ground.
“The bull gang goes on foot patrol, allowing for immediate investigation and action to be taken to treat the ground in time,” Ubull said.
Despite the extensive soil investigation and the ground treatment carried out, the risk of road settlement or a sinkhole appearing cannot be totally dismissed.
As a contingency, Jalan Sungai Besi will have lane closures in stages between now and Aug 10.
The scheduled closures covering a total of 50m across 13 lanes will happen in stages over two weeks.
However, should any emergency situation arise requiring full traffic closure, road closures will be immediately announced.
From Aug 28 to Sept 10, a second TBM will trail the same path to cross Jalan Sungai Besi. As such, the same lane closures will be implemented.
Roads users are advised to use alternative routes to Jalan Istana, Jalan Tun Razak and to Seremban during peak hours to reduce traffic build-up during the two weeks when each machine crosses Jalan Sungai Besi.
Road users can call 1800-82-6868 for further information.