Howrah Bridge
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The Howrah Bridge is a bridge that spans the Hooghly River in West Bengal, India. It was originally named the New Howrah Bridge because it links the city of Howrah to its twin city, Kolkata (Calcutta). On 14 June 1965 it was renamed Rabindra Setu, after Rabindranath Tagore a great poet and the first Indian Nobel laureate. However it is still popularly known as the Howrah Bridge.
The bridge is one of three on the Hooghly River and is a famous symbol of Kolkata and West Bengal. Apart from bearing the stormy weather of the Bay of Bengal region, it successfully bears the weight of a daily traffic of approximately 150,000 vehicles and 4,000,000 pedestrians. It is one of the longest bridges of its type in the world.
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[edit] History
By 18th century AD, Calcutta and Howrah on the opposite banks of Hooghly River had grown up to be the most important economic and cultural centers of British India, and a need for bridging the Hooghly River arose. To address this challenge the famous Floating Pontoon Bridge was built in 1874 by Sir Bradford Leslie.
The Floating Pontoon Bridge was built using timber on pontoon. The bridge was opened to let river traffic through. The bridge had hinged shore spans since Hooghly River is subjected to tides. During high tides these became very steep and bullock carts were not able to negotiate their way, which resulted in traffic jams. It was also feared that the floating bridge could affect river currents and cause silting problems. With time the bridge became too inadequate for the ever increasing traffic.
Due to all these reasons Government of Bengal in 1933 decided to replace the Floating Pontoon Bridge. The Floating Pontoon Bridge which was originally commissioned to service for 25 years, was decommissioned on February 1943, after its long service of 69 years.
Construction of the New Howrah Bridge was started on 1937. The Cantilever Era was prevailing at that time, and engineers felts that cantilever bridges were more rigid than suspension bridges. This bridge is one of the finest cantilever bridges in the world - left to India by the British engineers.
Considering various aspects like navigational, hydraulics, tidal conditions of the river and the projected traffic conditions, Rendel Palmer & Tritton came up with a design for a cantilever bridge of 1500 feet, with a 71 feet wide roadway and two 15 feet wide cantilever footways. Considering the quotation from various firms, the contract was awarded to Cleveland Bridge & Engineering Co. Ltd of Darlington, with a strong recommendation that they use Indian-made steel, which they agreed to do. Out of the total 26,500 tons of steel used, Tata Iron and Steel Company supplied 23,500 tons of steel and fabrication was done by Braithwaite, Burn and Jessop Co. at four different shops in Calcutta.
The two huge caissons which was sunk (on the first stage of construction) is still the biggest ever sunk caisson on land. It is told that while clearing the muck, all kinds of curious things was brought up, which included anchors, grappling irons, cannons, cannon balls, brass vessels, variety of coins. 40 Indian crane drivers were trained on the job and worked in three shifts of 8 hours each. The job of sinking the caisson were carried out round-the-clock at a rate of a foot or more per day.
One night, while grabbing out the muck to enable the caisson to move, the ground below it yielded and the entire mass plunged down two feet, shaking the ground. The impact of this shake was so intense that the seismograph at Khidirpore had registered as earthquake and a Hindu temple on the shore was destroyed; which was subsequently rebuilt. In spite of these challenging situations the caissons were placed true to position.
To keep the water out at depth of 103 feet (31 m) around the foundations so that construction can be done, around 500 people were employed on the compressed air operation. The air pressure maintained was about 40 lbs per square inch (2.8 bar). The work on the foundation was completed on November 1938. By the end of 1940 the erection of the cantilever arms was commenced and was completed in mid-summer of 1941. The two halves of the suspended span, each 282 feet (86 m) long and weighing 2,000 tons, were built in December 1941. 16 hydraulic jacks, each of 800 ton capacity were pressed in to service for joining the two halves of the suspended span.
After completing the steel work of the deck and concreting of roadway. the New Howrah Bridge was finally opened to traffic on February 1943. The old Floating Pontoon Bridge was decommissioned. In May 1946, census of the daily traffic on the bridge was taken and it was found to be 27,400 vehicles, 121,100 pedestrians and 2,997 cattle. The rate of only vehicle traffic over the bridge was 20% more than that on the London Bridge, in the same period, which was till then the busiest bridge in the metropolis.
The final cost of the bridge amounted to ₤2,500,000.
[edit] Description
The New Howrah Bridge was built between 1937 and 1943 and had a single 450 m span. It is technically a cantilever truss bridge, constructed entirely by riveting, without nuts or bolts. It is currently used as a road bridge, but previously had a tram route as well. The bridge also has sister bridges over the river at different points, namely the Vidyasagar Setu and the Vivekananda Setu.
Howrah Bridge is the gateway to Kolkata. Built on the Hooghly River, its original purpose was to facilitate military transportation between Kolkata and the industrial town of Howrah during World War II. It remains an cantilever bridge connecting the city to its main railway station, the Howrah Station, the one of the busiest railway stations of the world.
The bridge is 705 meters long and 97 feet (30 m) wide. More than 26,500 MT of high-tensile steel went into this unique bridge supported by two piers, each nearly 90 meters above the road. An engineering marvel, it expands as much as a meter during a summer day. The eight-lane bridge carries a steady flow of approx 150,000 vehicles, 4,000,000 pedestrians and thousands of cattle every day. Its best view is from the middle of the river (but photography there is prohibited). The ferries running from below the Howrah Station another way to cross the river and view the bridge.
Howrah Bridge was also the title of a 1958 Bollywood film starring Madhubala, and Ashok Kumar.
[edit] Technical details
| Details [1] | |
|---|---|
| Built | 1937—1943 |
| Location | Kolkata, West Bengal, India |
| Current status | In use |
| Crosses | Hooghly river |
| Type | Balanced Cantilever Suspension |
| Usage | Road bridge |
| Daily Traffic | 150,000 vehicles, 4,000,000 pedestrians |
| Builders | |
| Material | Steel |
| Tower height | 82 m |
| Number of spans | 3 |
| Length of spans | 99.125 m
457.50 m 99.125 m |
| Length of drop-in span | 172.02 m |
[edit] References
- ^ Howrah Bridge in the Structurae database
