Delhi Metro authorities began the launching work on the Janakpuri West – RK Ashram Marg corridor, which is currently under construction with a specially designed launcher attached with a transporter for the launch of U-girders on the elevated section. The launcher was made operational on Monday, July 5, for the construction of a 9.5 kilometre long viaduct from Mukarba Chowk to Ashok Vihar covering four metro stations – Majlis Park, Bhalswa, Azadpur, and Ashok Vihar, and a connection to the depot from Majlis Park.
The installation of U-girders was done with the help of two cranes having a capacity 350/400T which were placed at each pier location, in the earlier phases of construction.The U-girders were transported at each pier location with the support of a long trailer with an approximate length of 42 metres. This process was challenging for the metro authorities in the congested urban areas of the national capital.
The U-girder was carried by the Transporter from one designated point and is moved forward on rails laid on the already erected U-girders to add more U-girders further from the feeding point to the launcher.The new launcher with Transporter is fully electric with a much higher output compared to the conventional launchers or cranes. The U-girder is carried by the Transporter from one designated point and is moved forward on rails laid on the already erected U-girders to add more U-girders further from the feeding point to the launcher. The U-girders, as a result, are to be transported on trailers only up to the feeding point identified at a suitable location and not for the work’s entire length.
This new specially designed Launcher is 62 metres long and has a total weight of 230T. According to Delhi Metro, it can negotiate gradients up to 4 per cent and 200 metre radius curves. The Transporter is 41.75 metre long and has a total weight of 35T. The Transporter can travel with a speed of 3 km per hour at no load and 2 km per hour at full load.
The output of the new technology is higher as compared to the conventional method of the launching of U-girders. On average, four-to-six U-girders per day can be erected with the new launcher, whereas, with the conventional method, around two U-girders could be done in congested spaces of Delhi or other areas in the national capital region. Moreover, the erection work of U-girders with the conventional cranes could only be done during night hours as it requires the blocking of roads to position the cranes. Whereas, with the new launcher, the girders are transported with the transporter over the erected viaduct without any interface with the road from a single identified feeding point.