Kolkata is India’s third-largest metropolitan and economic area after Mumbai and Delhi. The city lies in the country’s northeastern state of West Bengal, near the border to Bangladesh. Around 14 million of its inhabitants and commuters rely on a good traffic infrastructure, which is why the Kolkata Metro Rail Corporation is systematically expanding the city’s metro network. 

In addition to the North–South line, line 2, which is currently under construction, is becoming increasingly important, as it is the only East–West line of the metro network. Upon completion, it will connect Kolkata to the neighbouring city of Howrah. The line will also connect key commercial centres as well as two of India’s most important long-distance and local railway stations, Sealdah in Kolkata and Howrah in the eponymous city. The line is expected to be fully operational in 2022. A significant challenge during the construction of metro line 2 involves crossing under the Hooghly river that forms the border between the two twin cities. This will be India’s first underwater tunnel and will measure a total of around eleven kilometres in length and 5.5 metres in width. The underwater section will measure approximately 520 metres in length. The project involves the construction of the country’s deepest metro station and the metro will pass through the deepest metro shaft. 

The stations are an important part of this unparalleled line. The walls of the stations consist of recycled concrete, reinforced concrete and bricks. The planners and architects, the Mumbai engineer and construction firm Afcons and the Moscow planning and construction firm Aecom Designs used heavy granite panels as cladding. The decision-makers took an in-depth look at how to ideally and reliably install these heavy panels while ensuring the safety of staff and passengers. The planners and contractors, which included Rainbow Infrastructure from Kolkata as well as the Godrej conglomerate from Mumbai in addition to Afcons and Aecom Design, ultimately opted for fischer undercut anchors. fischer India supplied an integrated solution consisting of a substructure and fixing solution that takes into account the heavy dynamic loads as a specialist project requirement. The selected fixing solution also allows the granite panels to be dismantled at a later stage.

Around 30,000 FZP II undercut anchors were used in combination with a Chinese substructure solution consisting of C-clasps and L-angle profiles, as well as fischer FBN II bolt anchors that are suitable for flexible applications in non-cracked concrete. “Our client was particularly convinced by the fact that our system solution which fastens the wall cladding in the stations meets the project’s high safety requirements”, says Jan Zimmermann, Market Manager façade systems at the fischer Group of Companies. Assessments (ETA) and approvals provide added assurance. Uday Shikhare, National Technical Manager fischer India, adds: “Our all-in-one service with which we have already accompanied our partner through various project phases also contributed to our successful cooperation”. This service included custom façade system design as well as the provision and instruction of the stationary SBN 502 drilling machine to create the undercut drill holes in the natural stone façade panels using a wet diamond drilling method.

fischer will continue to support its client until the successful completion of the stations’ wall cladding, which is expected to be completed by mid/late 2021 and will provide the right products and services for any fixing applications.