On 14 June 1965, it was renamed Rabindra Setu after the Bengali poet Rabindranath Tagore, who was the first Indian and Asian Nobel laureate.
It carries a daily traffic of approximately 100,000 vehicles[12] and possibly more than 150,000 pedestrians,[10] easily making it the busiest cantilever bridge in the world.
[15] In 1862, the Government of Bengal asked George Turnbull, chief engineer of the East Indian Railway Company, to study the feasibility of bridging the Hooghly River.
He reported on 19 March, with large-scale drawings and estimates, that:[16] In view of the increasing traffic across the Hooghly river, a committee was appointed in 1855–56 to review alternatives for constructing a bridge across it.
[17] The plan was shelved in 1859–60, to be revived in 1868, when it was decided that a bridge should be constructed and a newly appointed trust vested to manage it.
The Calcutta Port Trust was founded in 1870,[9] and the Legislative department of the then Government of Bengal passed the Howrah Bridge Act in the year 1871 under the Bengal Act IX of 1871,[9][17] empowering the lieutenant-governor to have the bridge constructed with Government capital under the aegis of the Port Commissioners.
Since June of that year it started opening at night for all vessels except ocean steamers, which were required to pass through during daytime.
[17] From 19 August 1879, the bridge was illuminated by electric lamp-posts, powered by the dynamo at the Mullick Ghat Pumping Station.
They referred the matter to Sir Basil Mott, who proposed a single span arch bridge.
Rendel, Palmer and Tritton were asked to consider the construction of a suspension bridge of a particular design prepared by their chief draftsman Mr.
The lowest bid came from a German company, but due to increasing political tensions between Germany and Great Britain in 1935, it was not given the contract.
Then in 1926 a commission under the chairmanship of Sir R. N. Mukherjee recommended a suspension bridge of a particular type to be built across the River Hoogly.
The fabrication and erection work was awarded to a local engineering firm of Howrah: the Braithwaite, Burn & Jessop Construction Co.
The impact of this was so intense that the seismograph at Kidderpore registered it as an earthquake and a Hindu temple on the shore was destroyed, although it was subsequently rebuilt.
[22] While muck was being cleared, numerous varieties of objects were brought up, including anchors, grappling irons, cannons, cannonballs, brass vessels, and coins dating back to the East India Company.
[13] Whenever excessively soft soil was encountered, the shafts symmetrical to the caisson axes were left unexcavated to allow strict control.
In very stiff clays, a large number of the internal wells were completely undercut, allowing the whole weight of the caisson to be carried by the outside skin friction and the bearing under the external wall.
Skin friction on the outside of the monolith walls was estimated at 29 kN/m2 while loads on the cutting edge in clay overlying the founding stratum reached 100 tonnes/m.
The bridge was erected by commencing at the two anchor spans and advancing towards the center, with the use of creeper cranes moving along the upper chord.
[7] The bridge deck hangs from panel points in the lower chord of the main trusses with 39 pairs of hangers.
These joints divide the bridge into segments with vertical pin connection between them to facilitate rotational movements of the deck.
[5] The bridge deck has longitudinal ruling gradient of 1 in 40 from either end, joined by a vertical curve of radius 4,000 feet (1,200 m).
Trams departed from the terminus at Howrah station towards Sealdah, Rajabazar, Shyambazar, High Court, Dalhousie Square, Park Circus, Ballygunge, and Tollygunge.
An investigation in 2003 revealed that as a result of prolonged chemical reaction caused by continuous collection of bird excreta, several joints and parts of the bridge were damaged.
[10] As an immediate measure, the Kolkata Port Trust engaged contractors to regularly clean the bird droppings, at an annual expense of ₹500,000 (US$5,800).
[26] The bridge is also considerably damaged by pedestrians spitting out acidic, lime-mixed stimulants (gutka and paan).
[27] A technical inspection by Port Trust officials in 2011 revealed that spitting had reduced the thickness of the steel hoods protecting the pillars from six to less than three millimeters since 2007.
KoPT announced that it will spend ₹2 million (US$23,000) on covering the base of the steel pillars with fibreglass casing to prevent spit from corroding them.
[32] The damage was so severe that KoPT requested help from Rendall-Palmer & Tritton Limited, the original consultant on the bridge from UK.