HYDERABAD:The Hyderabad Metro Rail has crossed another important milestone successfully by overcoming the toughest challenge.
Construction of a metro viaduct over the Punjagutta flyover, said to be an engineering feat, was accomplished. A 420-foot-long double-elevated viaduct as a three-span in-situ was successfully built without affecting the road traffic in any direction.
Construction of the viaduct over 85-odd traffic junctions in the twin cities was like building 85 flyovers and the viaduct over the Punjagutta flyover has proved to be the toughest so far.
Identified as one of the busy locations in the city with an already existing flyover, high volumes of traffic in different directions and the need for accommodating higher future traffic volumes posed several engineering challenges in the design and execution of the viaduct at Punjagutta.
Exhorted by chief minister K Chandrasekhar Rao to convert this challenge into an opportunity and create an engineering showpiece for the city, HMR managing director NVS Reddy held a series of meetings with LTMRHL managing director VB Gadgil, project director MP Naidu and others to evolve design and construction strategies.
As the flyover stands at a height of 23 feet above the road, the metro viaduct was planned to cross it at double elevation at a height of 51 feet from the road level. To allow future growth of traffic, the central span over the existing flyover was designed to be 190-foot long, totally supported by high-tensioned tendons (high-strength steel strands) which are anchored to adjacent spans of 115 feet each on both sides.
Deciding not to halt traffic in any direction between Banjara Hills and Begumpet, and between Ameerpet and Khairatabad even for an hour, ground- supported staging with wide gaps in between was devised, leaving enough carriageway for traffic flow on the road below and over the flyover during the viaduct construction period. A two-layer protection with safety net was provided to prevent fall of any material on road users.
To make the viaduct look aesthetic and to provide the required clearance over the flyover, an arch-type design was adopted for the viaduct. A special type of shuttering and girder arrangement by restricting their height to 7.5 feet was designed to get enough clearance (height) over the flyover for allowing vehicular movement during the construction stage.
After carefully arranging the support staging in such a manner, concreting of the viaduct, positioning and stressing of tendons, arrangement of bearings and removal of support shuttering were all carried out in nine stages over a period of four months.
Appreciating the aesthetics of the sleek structure, the chief minister remarked that Hyderabadis would surely be proud to see and enjoy the simultaneous movement of vehicles on the road and on the flyover and metro trains on the viaduct above the flyover.