Geology of the SiteĪ detailed description of the soil strata below the bed at the foundation locations was prepared by boring the soil at the location of the foundation. Due to higher corrosion resistance, the condition of the bridge is still intact in the area despite a very high degree of humidity and ambient temperature exceeding 40☌. With the use of higher percentages of copper and chromium, corrosion resistance was imparted into the elements of the structure. Out of this, 23,000 tons of steel was supplied by Tata Steel at Jamshedpur, India. Table-1: Properties of steel used in construction of the Howrah BridgeĪ total of 26,500 tons of steel was used in the construction of the bridge. These members were selected so that the strength and ductility requirements can be addressed during the construction and service stage. Table-1 illustrates the yield strength and ultimate strength of steel used in construction of the Howrah Bridge. In order to reduce the tonnage of the steelworks, certain specified steel members were used. Materials Used for the Construction of Howrah Bridge This option also ensured that the foundations were mainly subject to vertical loads.ģ. By cantilevering the span from the anchored span, river traffic was never affected. Balanced cantilever bridge: It was finally adopted because it allowed the construction of the main girder clear of the river, which carried huge commercial traffic.Floating bridge: It was rejected on account of its temporary nature and potential of collision with the river traffic.Pier and girder bridge: It was the most economical but was rejected due to likely change in the bathymetry of the river and the obstruction to river traffic.Suspension bridge: It was rejected on account of longitudinal pull on anchorages.Single-span arch bridge: It was rejected on account of a high lateral thrust.The committee examined the different types of bridge designs:
In 1922, a new Howrah Bridge commission was set up and a committee was formed for the planning phase of the project. Thus, the possibilities of any scour around the foundation was avoided.įigure-2: Existing pontoon bridge 2. The location of the bridge ensured that the main tower foundation kept clear of the waterway. The alignment was provided at a right angle to the flow. Due to the presence of some religious structures immediately upstream of the existing pontoon bridge, the site of the Howrah Bridge was selected so that the centreline of the bridge was 500 m away from the structures. The site of the Howrah Bridge was selected in such a way that the existing pontoon bridge could continue to cater to the traffic movement without any hindrance. Currently, it is the longest cantilever bridge in India and the sixth-longest cantilever bridge in the world. Howrah Bridge has a long span of 457 m and was the third-longest cantilever suspension bridge in the world till the year 1941. However, after the construction of the Howrah Bridge, it has become the main link connecting the city to the mainland. Therefore, the city had to depend on the main railway station at Howrah to enter the city. Kolkata was built on the river bank away from the mainland. Howrah Bridge is a balanced cantilever suspension bridge and has held the fancy of the people ever since its construction. Undoubtedly, this is attributed to the care and quality control exercised during its construction and the systematic maintenance protocol that has continued over the years.
But Howrah Bridge has needed very little repair and retrofitting and remained in sound structural condition. Other steel structures in the region have been susceptible to deterioration due to corrosion. Kolkata has a humid weather and a polluted environment. It remains in a good shape as a structure and is likely to serve the people of Kolkata for many more years to come. Howrah Bridge has recently completed 75 years of service for the twin Indian cities of Kolkata and Howrah and is considered as an iconic landmark of the city.
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