The Badarpur-Faridabad corridor of the Delhi Metro, set to be made operational by June, has come up at a record pace as specially designed beams were used in building the viaducts of the fully elevated line.
Officials in-charge of the project explained that the use of 'u-shaped' support beams or 'u-girders', which can measure up to 27 metres, helped in fast tracking the construction work of the 14-km-long corridor.
"Single segment of a viaduct can be built using only two spans of u-girders whereas several spans of normal girders would be required in building the same span as they have a length of not more than 2.5 metres," an official said adding that the technology was used at the Airport Express Line also, however, by a foreign contractor.
To further expedite the construction process, metro also used pre-cast girders, which could be brought to the sites and installed in a short span of time, at times in a single day.
Preliminary work for the corridor started in February 2012. Trial runs on it will begin tomorrow, the official said.
In contrast, another official said that it takes at least 5 days in building a segment through the conventional method. "Through engaging more labourers it can be done in 3 days".
Moreover, construction of portals are generally done on site as they are generally very long and heavy in nature. But the plan had to be shelved due to possibilities of hampering traffic on NH 2 for at least six months.
"Therefore, for the first time in DMRC's history, the decision to install precast portal beams was taken. These portal beams were cast at the casting yard and brought on site for installation," a spokesman said.
Giant 400-500 tonnes cranes were employed to carry the girders to the construction sites from the casting yard.
Metro faced further challenges on building certain alignments of the corridor, especially where the line moves to the left side of the highway from the right near the Badarpur toll plaza towards NHPC Chowk.
"On this stretch, the alignment curves about five times on a 300 m length. To take the alignment through these curves, six portals and five extended pier caps were also used for the first time on which the tracks rest," a metro official said.
To ensure that the five flyovers running parallel to the construction sites were not affected in any manner, DMRC had to work in close coordination with the National Highway Authority of India (NHAI).
