Mahatma Gandhi Setu

Mahatma Gandhi Setu was the longest river bridge in the world when opened in May 1982 — a 5.575 km balanced-cantilever pre-stressed concrete crossing of the Ganges connecting Patna (south bank) to Hajipur (north bank). The bridge was inaugurated by then-Prime Minister Indira Gandhi and remained the world's longest river bridge for over a decade.

Designed by Bridge & Roof Co. with HCC executing the construction, the bridge originally featured 46 PSC spans of 121.065 m each — at the time, the longest cantilever PSC spans built anywhere in India. The pre-stressing system used 12-strand parallel-wire tendons in 'CCL' configuration, then state-of-the-art.

By the early 2010s, the original concrete superstructure had degraded badly under heavy traffic (>50,000 vehicles/day vs the design value of 22,000). Rehabilitation began in 2017 — the only feasible option was to demolish the entire concrete superstructure and replace it with a steel truss superstructure on the original piers (which remained sound). Afcons executed the rehab between 2017-2022 at ₹1,742 crore. The reopened steel-superstructure bridge handles 65,000 vehicles/day.

The bridge is part of NH-19 (formerly NH-77) and provides Bihar's primary north-south road link.