Howrah Bridge

Howrah Bridge — officially Rabindra Setu since 1965 — is the third-longest cantilever bridge in the world and India's most iconic bridge. Sanctioned in 1939 to replace a creaking 1874 pontoon, the bridge was fabricated entirely from Indian-made steel (Tata Iron & Steel) using the new Tisco T1 grade — a wartime decision when British steel imports were impossible.

The structure carries an estimated 100,000 vehicles and 150,000 pedestrians daily without a single nut or bolt in its main truss — the entire steelwork is riveted (~26,500 tonnes of rivets). It was opened to traffic on 3 February 1943, with the first vehicle being a tram, although Allied authorities kept the opening unceremonious to avoid drawing Japanese air attention during WWII.

The two 80 m monolithic concrete caissons supporting the towers were sunk to bedrock through the Hooghly's silt using the pneumatic caisson method, then a leading-edge technique. The bridge requires no expansion joints in its main span — temperature-induced length changes are absorbed by the cantilever geometry.

The deck has been progressively re-surfaced and the rivets periodically replaced; major rehabilitation in 2018-19 (₹125 crore) added cathodic protection against the salt-spray Hooghly environment. The bridge is recognised as a Heritage Engineering Structure by ASCE.