Smt. Darshana Jardosh, Minister of State for Railways and Textiles, today initiated the casting of another 40-meter span Full Span Pre-Stressed Concrete (PSC) Box Girder for NHSRCL's Mumbai-Ahmedabad High-Speed Rail Corridor at the Navsari Casting Yard in Gujarat. Last month, on October 28th, the first Full Span Girder was cast at the casting yard in Anand, Gujarat.
On this occasion, Smt. Darshana Jardosh congratulated NHSRCL and L&T, stating, "Even when the country was grappling with Corona, NHSRCL and L&T continued their work with full vigor, adopting Corona-related safety measures, and brought this project to its current stage." She also mentioned that work on this project is progressing very rapidly and this infrastructure will soon become visible.
The 40-meter span PSC Box Girder weighs approximately 970 metric tons, making it the heaviest PSC Box Girder in India's construction industry. The 40-meter span girder is being cast as a single piece, meaning without any construction joints, and includes 390 cubic meters of concrete and 42 metric tons of steel.
To accelerate the construction of the viaduct, the substructure and superstructure have been built in parallel. Substructure work, including piles, pile caps, piers, and pier caps, is in progress. For the superstructure, casting yards have been developed along the alignment to cast Full Span Girders and Segmental Girders, enabling them to be launched onto cast pier caps using heavy machinery.
Most of the girders for the superstructure will be full span, 30, 35, and 40 meters long. However, for locations with site constraints, segmental launching of precast segments will be used. Full span girders are preferred over segmental girders as full span girder launching is seven times faster than segmental girder launching.
Along the alignment, 23 casting yards are being developed for casting the girders. Each casting yard spans an area of 16 to 93 acres, as per requirement, and is located near the high-speed rail alignment. To ensure rapid casting of girders with quality, facilities like jigs for rebar cage fabrication, casting beds with hydraulically operated pre-fabricated molds, batching plants, aggregate stacking areas, cement silos, quality laboratories, and workman camps have been developed at each casting yard.
Full Span Pre-cast Box Girders will be launched using heavy machinery such as straddle carriers, bridge launching gantries, girder transporters, and launching gantries. To ensure a continuous supply of girders for launching, box girders will be cast in advance at the casting yard and stacked systematically. A straddle carrier will pick up the box girder from the stacking yard and feed it to the bridge launching gantry, which will lift the box girder and place it on the bearings over the pier cap. The bridge launching gantry will launch the first 3-4 box girders, on which the girder transporter will be placed, and the launching of girders will continue in a sequential manner using the girder transporter and launching gantry.
The planning of casting yards and heavy machinery for launching has been done to meet a peak requirement of approximately 300 full span box girder castings and launches per month, which is equivalent to approximately 12 kilometers of superstructure casting and erection in a month.
The Mumbai-Ahmedabad High-Speed Rail Project (MAHSR) is 508 km long. Out of 508 kilometers, 352 kilometers are located in Gujarat state (348 kilometers) and Dadra and Nagar Haveli (4 kilometers), with the remaining 156 kilometers in Maharashtra state. M/s L&T is the executing agency for 325 km out of the 352 km length. They have been awarded two packages: C4 (237 km) and C6 (88 km).