The Bandra–Worli Sea Link , officially called Rajiv Gandhi Sea Link , is a cable-stayed bridge with pre- stressed concrete-steel viaducts on either side that links Bandra in the Western Suburbs of Mumbai with Worli in South Mumbai. [1] The bridge is a part of the proposed Western Freeway that will link the Western Suburbs to Nariman Point in Mumbais main business district. The 16 billion (US$260 million) bridge was commissioned by the Maharashtra State Road Development Corporation (MSRDC), and built by the Hindustan Construction Company. The first four of the eight lanes of the bridge were opened to the public on 30 June 2009. [8] All eight lanes were opened on 24 March 2010. The sea-link reduces travel time between Bandra and Worli during peak hours from 60–90 minutes to 20–30 minutes. [9] As of October 2009, BWSL had an average daily traffic of around 37,500 vehicles. [10]BWSL was designed as the first cable-stayed bridge to be constructed in open seas in India. Due to the underlying geology, the pylons have a complex geometry and the main span over the Bandra channel is one of the longest spans of concrete deck attempted. Balancing these engineering complexities with the aesthetics of the bridge presented significant challenges for the project. The superstructure of the viaducts were the heaviest precast segments to be built in India. They were built using a span-by-span method using overhead gantry through a series of vertical and horizontal curves. The 20,000 tonne Bandra-end span of the bridge deck is supported by stay cables within a very close tolerance of deviations in plan and elevation. [14] The Bandra–Worli Sea Link is the first infrastructure project in Mumbai to use seismic arresters. Seismic arresters will enable the sea link to withstand earthquakes measuring up to 8.0 on the Richter scale .The largest pylons for the bridge consist of diamond shaped 128 metres (420 ft) high concrete tower featuring flaring lower legs, converging upper legs, a unified tower head housing the stays and a continuously varying cross section along the height of tower. The bridges pylon towers gradually decrease in cross-section with height. They have horizontal grooves every 3m in height, which permitted inserts. Vertical grooves in the circular sections require special form liners, as well as require attention for de-shuttering. The tower legs are inclined in two directions, which presented challenges in alignment and climbing of soldiers. Construction joints were permitted at 3m intervals only. To build the pylons, Doka of Austria was commissioned to build a custom automatic climbing shutter formwork system, based on their SKE-100 automatic climbing shutter system. This was fabricated on site and employed to execute all tower leg lifts below deck level. Pre-cast yard The pre-cast yard was located on reclaimed land. The yard catered to casting, storing and handling of 2342 concrete-steel pre-cast segments for the project. The storage capacity requirement of yard was about 470 precast segments. As the area available was limited, the segments were stored in stacks of up to three layers.The cable-stayed portion of the Bandra channel is 600 metres (2,000 ft) in length between expansion joints and consists of two 250-metre cable supported main spans flanked by 50 metres conventional approach spans. A centre tower, with an overall height of 128 metres above pile cap level, supports the superstructure by means of four planes of cable stay in a semi-harp arrangement. Cable spacing is 6.0 metres along the bridge deck. The cable-stayed portion of the Worli channel is 350 metres (1,150 ft) in length between expansion joints and consists of one 150 metres cable supported main span flanked on each side by two 50 metres conventional approach spans. A centre tower, with an overall height of 55 metres, supports the superstructure above the pile cap level by means of four planes of cable stay in a semi-harp arrangement. Cable spacing here is also 6.0 metres along the bridge deck. The superstructure comprises twin precast concrete box girders with a fish belly cross sectional shape, identical to the approaches. A typical Pre-Cast segment length is 3.0 metres with the heaviest superstructure segment approaching 140 tonnes. Balanced cantilever construction is used for erecting the cable supported superstructure as compared to span-by-span construction for the approaches. For every second segment, cable anchorages are provided. A total of 264 cable stays are used at Bandra channel with cable lengths varying from approximately 85 metres to nearly 250 metres. The tower is cast in-situ reinforced concrete using the climbing form method of construction. The overall tower configuration is an inverted Y shape with the inclined legs oriented along the axis of the bridge. Tower cable anchorage recesses are achieved by use of formed pockets and transverse and longitudinal bar post-tensioning is provided in the tower head to resist local cable forces. A total of 160 cable stays are used at Worli channel with cable lengths varying from approximately 30 metres minimum to nearly 80 metres maximum. Like the Bandra channel, the tower here is also cast in-situ reinforced concrete using the climbing form method of construction but the overall tower configuration is I shape with the inclined legs. Similarly, tower cable anchorage recesses are achieved by use of formed pockets. The foundations for the main tower comprise 2- metre-drilled shafts of 25-metre length each. Cofferdam and tremie seal construction have been used to construct the six-metre deep foundation in the dry.
Posted on: Tue, 11 Mar 2014 04:26:09 +0000
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