The National High Speed Rail Corporation (NHSRCL) has commenced the casting of the first full span pre-stressed concrete (PSC) box girder of 40 mtr span to expedite the construction of a viaduct for Mumbai-Ahmedabad High-Speed Rail Corridor (MAHSR), in a casting yard in Anand, Gujarat, on 28 October 2021.

PSC box girder of 40 trm span weighs around 970 tonne and will be the heaviest PSC box girder in the construction industry of India.

The span girder is being cast in a single piece i.e. without any construction joint, involving 390 cum of concrete and 42 tonne of steel.

The Mumbai-Ahmedabad High-Speed Rail Project is 508 km long and out of 508 km, 352 km lies in the state of Gujarat (348 km) and Dadra and Nagar Haveli (four km), and the balance 156 km lies in the state of Maharashtra. Out of 352 km, Larsen & Toubro (L&T) is the executing agency for 325 km length.

To expedite construction of a viaduct, construction of substructure and superstructure has been taken up in parallel. While the work of substructure i.e. pile, pile cap, pier and pier cap, is in progress, for superstructure casting yards have been developed along the alignment to cast full span girders and segmental girders so that they can be launched using heavy machinery over casted pier caps.

For casting of the girders, 23 casting yards are being developed along the alignment. Each casting yard is spread in an area of 16 to 93 acre as per requirement and located near to the alignment. For expeditious casting of girders with quality, facilities like jigs for making rebar cage, casting beds with hydraulically operated pre-fabricated moulds, batching plants, aggregate stacking area, cement silos and labour camps have been developed in each casting yard.

Most of the girders will be of full span 30 mtr, 35 mtr and 40 mtr. However, for locations having site constraint, segmental launching of small precast segments will be used. Full span girders are preferred over segmental girder as their launching progress is seven times faster.

These precast girders will be launched using heavy machinery like straddle carrier, bridge gantry, transporter and launching gantry.

The straddle carrier will pick the box girder from the stacking yard and feed to the bridge gantry, which in turn will lift the box girder and place it over the bearing on pier cap.

Bridge gantry will launch the first three to four box girders, on which girder transporter will be placed and further launching of girders in sequential manner will continue using transporter and launching gantry.