New Delhi: The Delhi Metro Rail Corporation (DMRC) has introduced a major innovation in its construction technology by starting launching work on the Janakpuri West – RK Ashram Marg corridor with a specially designed launcher attached with a transporter for the launch of U-girders on its elevated section. The launcher started work near Majlis Park in the presence of DMRC's Managing Director (MD) Dr Mangu Singh and other senior officials, DMRC said in an official statement released Monday.
In the earlier phases of construction, the erection of U-girders was done with the help of two cranes of capacity 350/400T which were placed at each pier location and the U-girders were transported at each pier location with the help of a long trailer having an approximate length of 42m. In a congested urban area like Delhi, it used to be very challenging to find adequate space for positioning these heavy capacity cranes which occupy a lot of space. In addition, transporting the U-girders of 28m length with such long trailers was also a herculean task as roads in the NCR are either too congested or have massive traffic volumes even during the night time. These limitations often discouraged the use of U-girders in construction in spite of the fact that the U-girders are the most suitable structures for viaducts in terms of cost and time.
"This new state of the art launcher with transporter is fully electric with much higher output in comparison to the conventional launchers or cranes. The transporter carries the U-girder from one designated point and moves forward on rails laid on the already erected U-girders to further add more U-girders from the feeding point to the launcher. As a result, the U-girders are to be transported on trailer only up to the feeding point identified at a suitable location and not for the entire length of work. This results in much less requirement of space," DMRC said in an official press release.
"This new launcher is 62m long having a total weight of 230T. It can negotiate gradients up to 4 percent and 200m radius curves. The Transporter which transports the U-girder is 41.75m long having a total weight of 35T. It can travel with a speed of 3 kmph at no load and 2 kmph at full load," it added.
The output of this new innovation is quite high as compared to the conventional method of the launching of U-girders. On average, 4 to 6 U-girders per day can be erected with this Launcher whereas, with the conventional method, about 2 U-girders can be done in congested working environments like in Delhi – NCR. The erection work of U-girders with conventional cranes can be done only during the night as it requires blocking roads to position the cranes. Whereas in the case of this new Launcher with Transporter, U-girders are transported with the Transporter on the erected viaduct without any interface with the road from a single identified feeding point.
Such technology is being used for the first time in India. The total load of U-girders to be erected is as high as 160 tons and 462 such U-girders are to be erected in the contract. This launcher today has been made operational for the construction of a 9.5-kilometre-long viaduct from Mukarba Chowk to Ashok Vihar covering four stations namely Bhalswa, Majlis Park, Azadpur and Ashok Vihar and a connection to the depot from Majlis Park.
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