WHY GO UNDERGROUND?
With part of the 51km Klang Valley Mass Rapid Transit (KVMRT) Sungai Buloh-Kajang Line (SBK Line) designed to traverse through heavily built and populated residential districts, business centres, commercial centres and key employment areas in the urban and suburb corridors of Klang Valley, some 9.5 km of the alignment was taken underground.
The Sungai-Buloh Kajang Line (SBK) traverses through a tightly developed corridor, with 9.5 km of it underground in tunnels, served by seven below ground stations.
The 18 km of tunnelling is primarily through two key geological formations, Kenny Hill and KL Limestone, with the latter weathered to Grade V (tropical), all to be carried out with ten tunnel boring machines.
With almost half of the tunnel alignment sitting in the Grade V karstic limestone, MMC-Gamuda had proposed for this section a twin mode tunnel boring machine (TBM) that would operate in both ‘slurry’ and ‘EPB’ modes, plus additionally equipped with facility to use a higher density slurry. On this project six twin-mode TBMs with variable density provision were proposed to undertake 7.5 km of tunneling through the limestone, which was completed end June 2014 from the initial launch in May 2013.
The VD TBM has been attracting attention from industry specialists for its precise performance in tackling karstic limestone. This machine is a direct evolution from MMC-Gamuda’s tunnelling experience on the dual purpose SMART tunnel project in Kuala Lumpur through similar karstic limestone, but obviously without the variable density provision and as a result with less control on ground loss.
Additionally, VD TBM has the provision to be converted from slurry mode to EPB with just a short stoppage of a week to 10 days to install the alternative mucking system. This feature is indeed much needed at the point of transition in Bukit Bintang, where there is absolutely no provision possible for retrieval/launch shafts.
Tunnels have been a hallmark of human civilisation since prehistory and though their primary function is to create a direct route through an otherwise impassable medium, their actual use has been extremely varied. From the labyrinthine network of the London Metro and the New York subway system to the Cu Chi tunnels in Vietnam, tunnels are ubiquitous in modern society.
Tunnels are as much a part of the landscape here in Malaysia as well, with examples ranging from passages that cut through the mountainous interior of the peninsular to the underground LRT network beneath Kuala Lumpur city.
The SBK Line underground alignment will have strategic stops at the busiest commercial, residential and key employment areas in the heart of metropolitan Kuala Lumpur.
There is also the innovative, award-winning Stormwater Management and Road Tunnel (SMART) project located in the heart of the Kuala Lumpur city, which is the world’s first dual purpose tunnel combining a flood tunnel with a double-decked motorway. Innovated and built by MMC GAMUDA Joint Venture Sdn Bhd, the SMART project has become a crucial artery in-and-out of the city for both motorists and troublesome flood waters.
With part of the 51km Klang Valley Mass Rapid Transit (KVMRT) Sungai Buloh-Kajang Line (SBK Line) designed to traverse through heavily built and populated residential districts, business centres, commercial centres and key employment areas in the urban and suburb corridors of Klang Valley, MMC Gamuda KVMRT (T) Sdn Bhd, faced with land constraints, had little alternative but to take 9.5km of the alignment underground. The underground stretch begins near the intersection between Jalan Semantan and Jalan Duta, before winding through Muzium Negara, Pasar Seni, Merdeka, Bukit Bintang, Tun Razak Exchange (TRX), Cochrane, and ends at Maluri.
Due to crucial reasons such as constructability, cost and operational efficiency, the only solution was to go underground to avoid impediments to the social and economic vibrancy of Kuala Lumpur city.