Rehablitation of Mahatma Gandhi Setu in Patna

The Mahatma Gandhi Bridge was constructed about 25 years ago over the Ganges River in order to connect patna to the other side of river. Once completed it was supposed to be the part of N.H 19 and comes directly under Central Government of India. It is one of the longest bridge in india.
The bridge has 46 spans each with length 120m. Each span has two cantilever beams on both sides which are free to move at the ends. It has two lanes one upstream and the other downstream each with a width of around 6m. Both the lanes are also free from each other and are not connected anywhere. It was constructed by using 3 meter pre-casted parts being joined
at both ends to complete the span.
The Spans are connected by using a Protrusion which is free to move longitudinally also along the river flow. In upwards and downwards direction it is such that it allows vibration to transfer smoothly to the next span while vehicular movement without much discreteness. It is shown in fig. Due to heavy traffic movement and being the only bridge to cross ganges river the bridge is used heavily now. Hence it has started vibrating with a higher amplitude than it was designed to. Also in many spans the cantilever beams were found to have sagged at ends. Read full case study Mahatma-gandhi-Setu-Patna