In the vibrant city of Mumbai, a remarkable engineering feat stands proudly along the coastline – the Bandra-Worli Bridge, now famously known as the Rajiv Gandhi Sea Link. This iconic structure is not just a bridge but a testament to modern infrastructure, designed to alleviate the notorious traffic congestion in India’s bustling commercial capital.
Stretching over 5.6 kilometers, the Bandra-Worli Bridge boasts two parallel four-lane carriageways, catering to both northbound and southbound traffic. What sets it apart are several noteworthy firsts in India: the pioneering use of only precast segments, the distinction of being the first cable-stayed bridge across the open sea, and the unique feature of a single central pylon. The visual appeal of the bridge is enhanced by the presence of two cable-stayed bridges on each carriageway, making it a masterpiece in bridge aesthetics.
The project site, situated in the Deccan trap province of India’s central-west coastal region, reflects a geological history shaped by volcanic eruptions. The resulting lava formations and subsequent weathering gave rise to basalt rocks, with the project site falling within the Malabar Hill and Nana Chowk lava flow unit. The varied strength of these rocks, coupled with the presence of marine soil layers, presented a unique challenge for construction.
The foundation of this engineering marvel relied on the drilled shaft method, utilizing shafts with diameters of 2 m and 1.5 m. A total of 676 drilled shafts, ranging in diameter, supported the entire project. The approach piers and tower foundations showcased a strategic use of drilled shafts, emphasizing load-carrying capacity ranging from 3.3 MN to 25 MN.
The construction method involved a meticulous process, beginning with casing installation using the Maxi Traction vibratory hammer. Drilling, concreting, and integrity testing were essential steps in ensuring the stability and strength of the drilled shafts.
The concrete mix, with a compressive strength of 50 MPa, was carefully poured into the shafts, with integrity tests conducted using cross-hole sonic logging.
The superstructure components – pylons, cables, and deck – define the Bandra-Worli Bridge’s overall design and functionality.
These crucial elements, inclined towards each other and merging at 98 m above the deck, support the cable-stayed bridge. Transverse and longitudinal post-tensioning ensures resistance to cable forces, with the tower head tapering towards the top.
Arranged in a semi-fan configuration, the 2250 km of high-strength galvanized steel wires support the entire bridge, offering a substantial load-bearing capacity of 20,000 tons.
Constructed using a hollow concrete box section, the deck’s precast segments and post-tensioning contribute to its flexibility, reducing bending and torsional stresses. The use of webs and props establishes a continuous multi-box section, allowing wider lanes for traffic.
The construction methodology involved a truss system for launching precast concrete segments, followed by cable installation, fine-tuning, and adjustments. The time-efficient use of a floating shear leg crane facilitated the transport of the truss girder from Bandra to Worli.
The construction sequence unfolded through meticulous steps, including pier foundation construction, pylon tower construction, deck installation, cable stressing, and final adjustments.
In conclusion, the Bandra-Worli Bridge stands as a testament to meticulous planning and execution, seamlessly blending functionality with aesthetic appeal. This engineering marvel not only connects the shores of Mumbai but also represents a symbol of progress and innovation in India’s infrastructure landscape.