NEW DELHI, INDIA (Metro Rail News): On October 28, 2021, NHSRCL began casting the First Full Span Pre-Stressed Concrete (PSC) Box Girder of 40-meter span in a casting yard in Anand, Gujarat, to speed the construction of the viaduct for the Mumbai-Ahmedabad High-Speed Rail corridor (MAHSR).
The biggest PSC Box Girder in the Indian construction sector will be a 40 m span PSC Box Girder weighing roughly 970 MT. The 40-meter Span Girder is cast in one piece, without any construction joints, using 390 cubic meters of concrete and 42 tons of steel.
To speed up the construction of the viaduct, the substructure and superstructure are being built simultaneously. While work on the substructure, such as the Pile, Pile Cap, Pier, and Pier Cap, continues, casting yards have been built along the alignment to cast Full Span Girders and Segmental Girders, which will be launched using heavy machinery over casted Pier Caps.
Twenty-three casting yards are being built along the alignment for the casting of girders. Each casting yard is positioned along the alignment and covers an area of 16 to 93 acres, depending on the requirements.
In each casting yard, facilities such as jigs for producing rebar cages, Casting Beds with Hydraulically Operated Prefabricated Molds, Batching Plants, Aggregate Stacking Area, Cement Silos, and Labor Camps have been developed to expedite the casting of Girders while maintaining quality.
The majority of the rafters will be Full Span 30, 35, and 40 m, but in places where space is limited, segmental launching of small precast segments will be used. Complete Span Girders are preferable to Segmental Girders since they launch seven times faster.
Heavy gear such as a Straddle Carrier, Bridge Gantry, Transporter, and Launching Gantry will be used to launch these Precast Girders. Girders will be cast in advance and stacked in an organized manner in these casting yards to assure a constant supply of girders for launching.
The Box Girder will be picked up from the stacking yard by the Straddle Carrier and fed to the Bridge Gantry, raising the Box Girder and positioning it over Pier Cap’s bearing. The Bridge Gantry will launch the first 3-4 Box Girders, after which a Girder Transporter will be placed, and the Girders will be launched in a sequential order using the Transporter and Launching Gantry.
The casting yards and heavy machinery for launching have been planned to fulfil the peak demand of around 300 Full Span Box Girder Casting and launch each month, which equates to approximately 12 kilometers of superstructure casting and erection per month.