Vidyasagar Setu / 2nd Hooghly Bridge - Kolkata, West Bengal

Description

Construction began on 3 July 1979, and the bridge was commissioned on 10 October 1992 by the Hooghly River Bridge Commission. The bridge is under the control of the Hooghly River Bridge Commissioners. The bridge is used by around 30,000 vehicles daily, considerably less than the bridge's capacity of 85,000.

Population and commercial activity grew rapidly after India gained independence in August 1947. The only link across the Hooghly River, the Howrah Bridge, between Howrah and Kolkata, was subject to much traffic congestion, with over 85,000 vehicles every day. This necessitated planning for a new bridge across the river so that it could connect to the major cities of Mumbai (Bombay), Delhi and Chennai(Madras) through the national highways located close to the bridge.

The foundation stone for the bridge was laid by Indira Gandhion 20 May 1972. The bridge took more than 22 years to complete and cost Indian Rupees 3.88 billion, but in seven of those years there was no construction activity. The bridge is named after the 19th-century Bengali educationist reformer Pandit Ishwar Chandra Vidyasagar. Work on the cable-stayed bridge started with the construction of the well curb on the Calcutta bank end on 3 July 1979, and when commissioned on October 10, 1992, it became the longest span bridge of this type in the world. At that time it was the first cable-stayed bridge in India, the largest in Asia and the third largest in the world.

Vidyasagar Setu is a cable-stayed bridge, with 121 cables in a fan arrangement, built using steel pylons 127.62 metres (418.7 ft) high. With a total length of 823 metres (2,700 ft), Vidyasagar Setu is the longest cable-stayed bridge in India and one of the longest in Asia. The deck is made of composite steel-reinforced concrete with two carriageways. The total width of the bridge is 35 metres (115 ft), with 3 lanes in each direction and a 1.2 metres (3 ft 11 in)-wide footpath on each side. The deck over the main span is 457.20 metres (1,500.0 ft) long. The two side spans are supported by parallel wire cables and are 182.88 metres (600.0 ft) long. Vidyasagar Setu is a toll bridge with free bicycle lanes. It has capacity to handle more than 85,000 vehicles in a day. The bridge was designed by Schlaich Bergermann & Partner, and checked by Freeman Fox & Partners and Bharat Bhari Udyog Nigam Limited. Construction was carried out by the consortium of "The Braithwaite Burn and Jessop Construction Company Limited (BBJ). The Hooghly River Bridge Commission (HRBC) was responsible for the commissioning operations of the bridge.

The design of the bridge differs slightly from other bridges, which are of live load composite construction. The difference is in the dead load design concept adopted for this bridge and concreting of the side spans done with support provided by the intermediate trestle. The deck is designed with a grid structure of girders. One set of girders are at the end and another set in the middle, which are braced by girders spaced on an average at 4.2 metres (14 ft) centre to centre.

A deck crane was used for the construction of the main span of the bridge. A specially designed crane of 45 tonne capacity was used to erect the pylons of the bridge. The structural steel used in the bridge weighs about 13,200 tonnes. The pylons, which are 128 metres (420 ft) in height, are designed as free standing portals. They are provided with two cross portal members, one at the bottom and another at the top, below the pylon head. The deck is connected to the end piers by bolts embedded in the chambers of the piers. Pylons made of 4x4m (13x13ft) steel boxes of riveted construction were raised on the two side spans of the bridge; one set is on the Calcutta side and the other is on the Howrah side. The six pylons on the Calcutta side of the bridge were installed using 75 MT and 50 MT cranes, while on the Howrah end, a single 50 MT crane was used. Anchorage of the pylon with the base of piers was effected through Dywidag rods, duly anchored in the piers. Cables were erected from the four pylon heads with the help of 32 MT hoist frames. The hoist frames were mounted on top of each pylon. Sheave blocks, winches and snatch blocks were used to facilitate the lifting, and cables inside the pylons were stressed with jacks. Pressure grouting was performed to fill the voids between the wire and the high-density polyethylene (HDPE) tubes. A two tonne tower crane, fixed inside the pylons, lifted the cables into position.

The bridge has been subject to prototype wind tunnel tests at the Indian Institute of Science in Bangalore. Bearings are used in vertical and horizontal directions, with grouted collars in four segments at the two end piers and horizontal bearings at the two middle piers to achieve stability against lateral movement. Maurer Söhne expansion joints were provided to allow for 400 millimetres (16 in) horizontal expansion at the free ends. Fixed end slab seal type expansion joints 115 millimetres (4.5 in) were used for horizontal expansion of the joints. Other essential components provided in the bridge structure are the handrails, lightning arresters, crash barriers, gas service support structures, telephone and electric lines, lifts in the pylons, and a maintenance gantry.

Key Features

Official Name: Vidyasagar Setu
Design: Cable Stayed Road Bridge with dead load composite deck structure
Total Length: 822.96 metres (2,700 ft)
Width: 35 metres (115 ft)
Longest Span: 457.2 metres (1,500 ft)
Construction Started: 3 July 1979
Opened to Traffic: 10th October 1992
Daily Traffic: 85,000 vehicles
Salient features: Side Spans- 182.88m each, Pylon- 122m high, 152 cables, Cable Weight- 1400 mt. Steel Work- 13200 mt. (appx), Supply, Fabrication & erection.