The Nazrul Setu or the Hydraulic Bascule Bridge in Khiddipore, Kolkata, is considered to be an important link between Garden Reach, Central and Eastern part of the City. Built by Waagner Biro Bridge System AG of Austria, the Bascule Bridge is owned and managed by the Shyama Prasad Port Trust of Kolkata.
The Nazrul Setu is Calcutta’s first Hydraulic Bascule Bridge that was made operational in 1966. The Bridge opens in two parts during a prefixed hour in order to let the ships and cargo vessels underpass from the dockyard smoothly. The opening of the Bascule Bridge in two folds is certainly a moment of watch, but, it is equally crucial to understand the concept of Bascule Bridge and it’s advantages.
The term hydraulic defines the movement of liquid in a confined space under pressure. The principle formula of developing a hydraulic bridge mathematically is derived from French scientist Blaise Pascal. Under hydraulic bridges, Bascule Bridge, Swing Bridge and Lifting Bridge are the three main types.
A Bascule Bridge is a movable bridge having counter weights to the span that may be located above or below the bridge. In a Bascule Bridge, the main girders ( a large steel or iron beam used for buildings bridges) can be lifted together with deck. Depending on the wind speed, the Bascule Bridge is designed as either single or double-leaf. The Khidirpore Bascule Bridge is a double-leaf bridge, in which the surface of the bridge unfolds into two sections diving a gap in order to give space for the movement of water vehicles, like ships and cargo vessels. The Bridge is controlled manually through hydraulic motors.
The Tower Bridge in London is not fully but a combination of suspension and Bascule Bridge built between 1886-1894. Although, the first Bascule Bridge was built in 1902 in the United States, called the MILWAUKEE BASCULE BRIDGE over the Chicago River. In India, the Pamban Railway Bridge in Tamil Nadu is the country’s first Bascule Bridge that concluded the construction in 1914. The Pamban Bridge is a cantilever bridge in origin but has a combination of Hydraulic Bascule to allow free movement of inland cargo transportation.
The Khidirpur Dock which was made officially commercial in 1884 by the East India Company, asserted the importance of inland waterway transportation. In the last 20 years, the Shyama Prasad Mukherjee Port Trust ( KoPT) has exchanged approximately 254.448 MT of goods. The dockyard back then was developed with amenities including cold storages and decks, which is still operational.
The construction of Bascule Bridge not only curbs inland waterway hindrances but also drops down logistic costs.
-Rituparna Dutta