Innovative Pier Saves Costly Special Span
Pier Bridges Challenge
Nagpur: Maha Metro has overcome one of the most complex engineering challenges on its Phase-II network by successfully constructing the viaduct across Hyderabad-Jabalpur Road (NH-44), using an innovative design that turned a narrow 3.5-metre gap between two highway bridges into the foundation for the metro structure. The solution not only eliminated the need for a costly special span but also ensured uninterrupted traffic on one of the city’s busiest highway intersections.Instead of opting for a long special span, engineers identified a 3.5-metre gap between the carriageways where a central metro pier could be safely constructed. This allowed two conventional viaduct spans to be erected, resulting in significant savings in both construction cost and time.While the plan was drafted, executing it required equally innovative construction methods. Conventional hydraulic piling rigs, which stand around 14 to 15 metres high, could not be accommodated beneath the bridge deck located barely 8.5 metres above ground.Engineers redesigned the piling arrangement, so the equipment operated entirely within the available gap, allowing foundation work to proceed without affecting traffic movement. The pier and pier cap were subsequently cast under stringent safety protocols before segmental box girders were erected across the highway.Maha Metro said the viaduct has been built with a vertical clearance of 6.5 metres above the highway bridge, exceeding the minimum 6-metre requirement prescribed under its agreement with the National Highways Authority of India (NHAI). The segment erection was carried out by launching the gantry LG Shivalik with minimal dependence on the existing bridge structure.Reach-4A is among the most engineering-intensive sections of Nagpur Metro Phase-II. With the NH-44 crossing now completed, construction on the corridor has gained further momentum, bringing the eastern extension of the metro network a step closer to completion.The breakthrough was achieved on the 5.33-km Reach-4A corridor between Prajapati Nagar and Transport Nagar, an extension of the Aqua Line. The stretch includes three elevated stations — Pardi, Kapsi Khurd and Transport Nagar — and a nearly 2-km-long double-decker viaduct being constructed above the existing Pardi flyover.Crossing NH-44 posed a unique challenge as the metro alignment intersected two parallel highway bridges carrying traffic towards Hyderabad and Jabalpur.
