Gantry Crane a Strong Option in Handling Soil & Precast in Tunnel Construction Site

Challenging Task

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Due to space constraints, it is always challenging to designate a mobile/crawler crane launching space in a congested tunnel construction site for the handling of excavated soil. Predictably, there are many activities in construction site that involves heavy lifting. This is especially so in tunnel construction sites with activities like launching of tunnel boring machine (TBM), the removal of excavated messy soil from tunnel and the fixing of the precast tunnel segments. These activities require the assistance of heavy lifting equipment.

As the weight of the tunnel boring machine is extremely heavy, a tower crane is unable to undertake such a heavy lifting job. Thus, a good substitution will be a rail mounted gantry crane aside from mobile/crawler crane. The rail mounted gantry crane is a better option as it could be engineered to travel in a very narrow & congested path and furthermore, it does not require launching spaces and driveways, which are necessary for mobile/crawler cranes.

A good example of gantry crane at work is found in Leighton John Holland’s MRT tunnel construction site.

Leighton John Holland Joint Venture was awarded a contract to construct the future Springleaf Station and its tunnels from Springleaf to Lentor Station. Therefore to facilitate material handling and soil excavation for the construction of the tunnels, Leighton John Holland JV had engaged MHE-Demag (S) Pte Ltd to design, supply and install two units of 50 ton, span 13m with 5m cantilever gantry cranes on site to handle tunnelling work for four tunnel drives.

Solution Offered by MHE-Demag Gantry Cranes

The two MHE-Demag gantry's cranes were installed in the last quarter of 2015. They were not only designed to meet the stringent specification, should also be able to manoeuvre in a very tight allocated space to support the critical operation at the tunnelling site. The hoisting capacity for the cranes is 50 ton with a hoisting speed ranging from 1.2 to 12 m/min. The lifting height above ground is 10m and below ground is 20m deep. At one glance, one can tell that these gantry cranes are very robust and special; each crane is completed with a 5m long cantilever arm to facilitate loading & unloading of precast tunnel segments from trucks. And to support & ease the hoisting of boring machine and precast tunnel segments in & out of the tunnel launching shaft, an overhead control cabin is installed to facilitate the smooth operation. Definitely, all necessary safety devices are put in place to ensure a safe & efficient operation.

Advantages of MHE-Demag Gantry Cranes

With the deployment of MHE-Demag's gantry cranes, precious construction space can be planned and utilized for other essential works. Provisions of launching spaces and driveways for mobile/crawler cranes are no longer required, thus making it possible for the construction site to be neatly & effectively arranged to achieve the optimal output. In addition, valuable time can be better managed on site, as there is no requirement to make time provision for mobilization of mobile/crawler cranes. In conclusion, a rail mounted gantry crane can certainly be a strong option for deployment in tunnel construction site for heavy lifting tasks.