Gantry Cranes in Tunnel Construction
Tuesday, October 25, 2016
Gantry cranes are a unique and effective solution for MRT projects
The Massive Rapid Transit (MRT) and Light Rail Transit (LRT) train system is one of the most popular modes of transport in Singapore with a ridership of well over two million passengers a day. The island-wide network has 142 stations and more are in the pipeline. In fact, the Singapore government is determined to double its rail network from today’s 178km to about 360km by 2030. This will mean that eight out of 10 households will live within a 10-minute walking distance of a train station.
The Thomson-East Coast Line (TEL) is currently under construction. It is a joint line between the Thomson Line (30km) and the Eastern Region Line (13km). The 43km TEL will add 31 new stations to Singapore’s existing rail network. It will feature seven interchange stations, connecting commuters to the East-West Line, North-South Line, North-East Line, Circle Line and the Downtown Line. When completed, TEL will be Singapore’s sixth rail line.
Changing Industry Needs
All recent MRT lines and stations are being constructed underground as they weave through dense residential estates. In traditional tunnel construction, the main contractor would deploy robust lifting systems to bring soil excavated from underground to ground level for disposal. The same lifting system would also be deployed to launch the Tunnel Boring Machine into the tunnel for boring activity. In the past, these lifting systems were mobile/crawler cranes stationed on-site. However, due to site constraints and limited space, contractors are now turning to rail-mounted gantry cranes as a more effective solution for lifting and excavation. Rail-mounted gantry cranes are also freeing up valuable space that once was set aside for mobile/crawler cranes.
Unique and Effective Solutions
MHE-Demag has been supplying gantry cranes to contractors for MRT projects since 1980. The first gantry it supplied was used in the construction of Bedok MRT station on the East-West Line. Since then, MHE-Demag has supplied and installed more than 40 units of gantry cranes for countless MRT tunnelling projects. Most recently, this includes Tan Kah Kee and Newton stations of Downtown Line 2 as well as Springleaf, Havelock and Shenton Way stations of TEL.
MHE-Demag’s success comes from its unique and highly effective solutions. Its gantry cranes are designed with special requirements in mind to support the critical operations at tunnelling sites. The hoisting capacity for these cranes range from 20 to 65 tonnes. They have hoisting speeds of 10 to 30 m/min with inverter control, and lifting heights of 20 to 40m below ground and nine to 15m above ground.
Even at a glance, these gantry cranes are very special. They incorporate robust winch systems with long hook paths and special braking systems. To facilitate the hoisting of muck cars, Tunnel Boring Machines, locomotive and precast tunnel beams in and out of tunnels, an overhead operator cabin is mounted at the crane girder to allow crane operators a clear and elevated view above the tunnel opening.
Due to the nature of the excavation work, a special muck car or clamshell crab is also often fitted to the lifting hook to lift and empty the soil excavated from the deep tunnel to the truck parked on ground level for disposal.
From Good to Great
In supporting MRT tunnelling projects, MHE-Demag has enhanced its gantry cranes from a simple solution to one that offers substantial safety features, such as a load display unit, data logger and lightning arrester. Audrey Wong, Senior Field Sales Manager, MHE-Demag Singapore, who leads many such projects, said: “Through years of supporting MRT tunnelling projects, MHE-Demag’s gantry crane has been refined and improved to meet the stringent requirements of tunnelling work.”
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