Bandra-Worli Sea Link 

Official name Rajiv Gandhi Sea Link

Carries 8 lanes of road traffic (including 2 lanes for buses only)

Crosses Mahim Bay

Locale Mumbai, Maharashtra, India

Maintained by Hindustan Construction Company

Designer Seshadri Srinivasan

Design Cable-stayed, Viaducts

Total length 5.6 kilometers (3 mi)

Height 126m

Longest span 250m x 2

Clearance below 20m

Beginning date of construction

2000

Completion date 21 April 2009

Opened 30th June, 2009

TollRs. 50 for one way Rs. 75 for to & fro

Connects Bandra toWorli

Coordinates 19°02′ 11″N 72°49′ 02″E 19.03648°N 72.81725°E / Coordinates:19°02′ 11″N 72°49′ 02″E 19.03648°N 72.81725°E /

 

The Bandra Worli Sea Link (BWSL) , officially the Rajiv Gandhi Sea Link , is a cable-stayed bridge with pre-stressed concrete viaduct approaches, which links Bandra and the western suburbs of Mumbai with Worli and central Mumbai, and is the first phase of the proposed West Island Freeway system.

The Rs. 1600 crore ($ 400 million approx.) project of  Maharashtra State Road Development Corporation (MSRDC) was executed by Hindustan Construction Company, with design and project management by DAR Consultants. The bridge was dedicated to the public on 30 June 2009 by Congress President and UPA Chairperson Sonia Gandhi, although only 4 of 8 lanes are in service.

The Sea Link reduces travel time between Bandra and Worli from 45–60 minutes to 7 minutes. The link has anaverage daily traffic of around 37,500 vehicles per day, about half the pre-opening estimate of 70,000.

Contents :

• 1 History

• 2 Overview

o 2.1 Purpose

o 2.2 Construction

o 2.3 Main Bridge Structure

2.3.1 Part - I North End Approach Structure

2.3.2 Part- II Cable-Stayed Bridge

2.3.3 Part - III South End Approach Structure

o 2.4 Toll Plaza

o 2.5 Intelligent Bridge System

o 2.6 Power Supply Distribution and Road Lighting System

o 2.7 Pre-Cast Yard

o 2.8 Marine Works

2.8.1 Foundation and Substructure 

2.8.2 Cable Stay bridges 

2.8.3 Pylon Tower Legs 

• 3 Engineering challenges 

• 4 See also

• 5 References

• 6 External links

 

• History

Mahim Causeway was the only link connecting the western suburbs to island city of Mumbai. This north-southwestern corridor would be highly congested resulting in a bottleneck at rush hours. The sea link was thus proposed to act as an alternate route between the western suburbs of Mumbai and central Mumbai, in additionto the existing Mahim Causeway, thus easing congestion. This link would also form a part of the larger WestIsland Freeway spanning the entire coastline.

The project was initiated more than 10 years ago in 1999 and was supposed to be completed within 5 years butit was delayed due to public interest litigations. The foundation stone was laid in 1999, by Shiv Sena supremoBal Thackeray.

It was to cost Rs 300 crore and finished in 2004.

Overview:

 The Bandra Worli Sea link, view from the Taj Lands End.

Purpose:

The BWSL project is a part of the Western Freeway Sea Project, which, in turn, is a part of a larger proposal toupgrade the road transportation network of greater Mumbai. It is primarily meant to provide an alternative to theMahim Causeway route that is presently the only connection between South Mumbai and the Western andCentral suburbs. The project starts from the intersection of  Western Express Highway and SV Road at theBandra end, and connects it to Khan Abdul Gaffar Khan Road (Worli Seaface) at the Worli end which in turnconnects to Mumbai's arterial Annie Besant Road at the Narayan Pujari Nagar corner. The MSRDC has previously planned to open the remaining four lanes of the sea link by March 2010. However, the gruesomeaccidents taking place in a short span of time has altered the decision and the remaining lanes are expected to bein operation by the end of January 2010.

The project has been commissioned by the Maharashtra State Road Development Corporation Ltd (MSRDC),designed by DAR Consultants and is being built by Hindustan Construction Company (HCC).

Construction:

The entire project was originally conceived as one large project comprising, different components, but in order to accelerate the overall construction schedule, the project has been divided into five construction packages.These packages helped, to an extent, to make the project meet its deadline.

 

 Package I : Construction of flyover over Love Grove junction at Worli

 Package II : Construction of cloverleaf interchange at Mahim intersection

 Package III : Construction of solid approach road from the Mahim intersection up to the start of the Toll Plazaon the Bandra side and a public promenade

 Package IV : Construction of Cable-Stayed Bridges together with viaduct approaches extending from Worli upto the Toll Plaza at Bandra end, Intelligent Bridge System (IBS).

 Package V : Improvement to Khan Abdul Gaffar Khan Road

Package IV is the largest and main phase of Bandra-Worli Sea Link Project that has been awarded to HCC thatincludes cable-stayed bridge, viaduct approaches extending from Worli up to Toll Plaza at Bandra end andModern Toll Plaza

Main Bridge Structure:

 The Bandra Worli Sea link, under construction, view from the Taj Lands End.

The bridge consists of twin continuous concrete box girder bridge sections for traffic in each direction. Each bridge section, except at the cable-stayed portion, is supported on piers typically spaced at 50 metres. Eachsection is meant for four lanes of traffic, complete with concrete barriers and service side-walks on one side.The bridge alignment is defined with vertical and horizontal curves. The bridge layout is categorized into threedifferent parts:

Part 1 - The north-end approach structure with Pre-Cast (PC) segmental construction.

Part 2 - The Cable-Stayed Bridge at Bandra channel is with 50m -250m-250m-50m span arrangement

and the Cable-Stayed Bridge at Worli channel is with 50m-50m-150m-50m-50m span arrangement.

Part 3 - The south end approach structure with Pre-Cast segmental construction.

 

Part - I North End Approach Structure:

The bridge is arranged in units of typically six continuous spans of 50 metres each. Expansion joints are provided at each end of the units. The superstructure and substructure are designed in accordance with IRCcodes. Specifications conform to the IRC standard with supplementary specifications covering special items.The foundation consists of 1.5 metres diameter drilled piles (4 nos. for each pier) with pile caps. Bridge bearings are of Disc Type.

The bridge has been built utilising the concept of Pre-Cast, post-tensioned, segmental concrete box girder sections. An overhead gantry crane with self-launching capability is custom built by the company to lay thesuperstructure of the precast segments. The Pre-Cast segments are joined together using high strength epoxyglue with nominal pre-stressing initially. The end segments adjacent to the pier are short segments "cast-in-situ joints". Geometrical adjustments of the span are made before primary continuous tendons are stressed.

Segment types are further defined by the changes in the web thickness and type of diaphragms cast in cell. Thesegment weights vary from 110 tonnes to 140 tonnes per segment. The segment length varies from 3000 mm to3200 mm. Deck post tensioning is performed at the completion of the erection of each 50m bridge span.

Part- II Cable-Stayed Bridge:

The cable-stayed portion of the Bandra channel is 600 metres in overall length between expansion joints andconsists of two 250-metre cable supported main spans flanked by 50 metres conventional approach spans. Acentre 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 in overall length between expansion joints andconsists of one 150 metres cable supported main span flanked by two 50 metres conventional approach spans. Acentre tower, with an overall height of 55 metres, supports the superstructure above the pile cap level by meansof four planes of cable stay in a semi-harp arrangement. Cable spacing here is also 6.0 metres along the bridgedeck.

The superstructure comprises twin precast concrete box girders with a fish belly cross sectional shape, identicalto the approaches. A typical Pre-Cast segment length is 3.0 metres with the heaviest superstructure segmentapproaching 140 tonnes. Balanced cantilever construction is used for erecting the cable supported superstructureas 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 metresminimum to nearly 250 metres maximum. The tower is cast in-situ reinforced concrete using the climbing formmethod of construction. The overall tower configuration is an inverted "Y" shape with the inclined legs orientedalong the axis of the bridge. Tower cable anchorage recesses are achieved by use of formed pockets andtransverse 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 metresminimum to nearly 80 metres maximum. Like the Bandra channel, the tower here is also cast in-situ reinforcedconcrete using the climbing form method of construction but the overall tower configuration is "I" shape withthe 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 metres length each. Cofferdam andtremie seal construction have been used to construct the six metre deep foundation in the dry.

 

Part - III South End Approach Structure:

This portion of the bridge is similar to the North end approach structure in construction methodology with span by span match cast concrete box girder sections.

Toll Plaza:

A modern toll plaza with 16 lanes is provided at the Bandra end. The toll plaza is equipped with a state-of-the-art toll collection system. A structure is provided at this location to house the control system for the ITS.

Intelligent Bridge System:

The toll station (TP) and collection system will provide for three different types of toll collection, as follows: -Fully automatic system: Electronic payment through On board Units mounted on the vehicles which allow passage without stopping. - Semi-automatic system: Electronic payment through a smart card, which allows payment without having to pay cash. - Manual toll collection: Payment of toll by cash, requiring vehicle driversto make cash payment to a toll attendant, and stopping for cash exchange.

The intelligent bridge system will provide additional traffic information, surveillance, monitoring and controlsystems. It comprises CCTVs, traffic counting and vehicle classification system, variable message signs, remoteweather information system and emergency telephones. The control centre located near the toll plaza is housedwith the electronic tolling controls. The transmission system comprises fibre-optic cable housed in PVCconduits running parallel to the Bandra-Worli corridor. In addition, facilities to assist enforcement are providedin the form of pullout locations, which will allow drivers and enforcement officers to safely pullout of traffic.

Power Supply Distribution and Road Lighting System:

A reliable and dependable power supply has been arranged for the entire project. It will also house dieselgenerator sets and auto mains failure panels to cater to critical load, e.g., monitoring, surveillance andcommunication equipment emergency services like aviation obstruction lights. Adequate levels of lightinglevels have been maintained and energy saving luminaries have been installed. Special emphasis has been givento incorporate lighting protection at bridge tower and control room building to protect those building/ structuresand the sophisticated monitoring and communication equipment installed therein.

Pre-Cast Yard:

The Pre-Cast yard is located on reclaimed land. The yard caters to casting, storing and handling of pre-castsegments for the project totalling 2342 in numbers. The storage capacity requirement of yard is to be about470nos. As the area available is limited, the segments are to be stored in stacks of three layers.

Marine Works:

Foundation and Substructure:

The foundations for the BWSL project consist of 2000-mm diameter piles numbering 120 for the cable-stayed bridges and 1500-mm diameter piles numbering 484 for the approach bridges. The project’s site geologyconsists of basalts, volcanic tuffs and breccias with some intertrappean deposits. These are overlain bycompletely weathered rocks and residual soil. The strength of these rocks range from extremely weak toextremely strong and their conditions range from highly weathered and fractured, to fresh, massive and intact.

 

The weathered rock beds are further overlain by transported soil, calcareous sandstone and thin bed of coarsegrained conglomerate. The top of these strata are overlain by marine soil layer up to 9m thick consisting of dark  brown clayey silt with some fine sand overlying weathered, dark brown basaltic boulders embedded in the silt.The major engineering problems that needed suitable solutions before proceeding with the work were asfollows:

1. Highly variable geotechnical conditions of the foundation bed as explained above. 2. Highly unevenfoundation bed even for plan area of one pile. 3. Presence of Intertidal Zone (Foundation Bed exposed in lowtide and submerged in high tide).

Cable Stay bridges:

It is for the first time that cable stay bridges have been attempted on open seas in India. Coupled with the factthat the aesthetically designed pylons have an extremely complex geometry and one of the longest spans for concrete deck, the challenges encountered were indeed formidable.

Pylon Tower Legs:

The salient characteristics of the pylon tower that make it complex and challenging from the point of view of constructability are as follows: (a) The section decreases gradually with height; (b) There are horizontal groovesat every 3m height and vertical grooves for circular portion that requires special form liners as well as itrequires attention for de-shuttering; (c) The tower legs are inclined in two directions, which creates complexitiesin alignment and climbing of soldiers; (d) Construction joints permitted only at 3m level. Inserts were permittedonly in horizontal grooves provided at 3m height. On not being able to get immediate solution from reputedworldwide formwork manufacturers, the project design team designed an automatic climbing shutter formwork system, which was fabricated on site and employed to execute all tower leg lifts below deck level. To affectfurther reduction in time cycles, HCC approached Doka, Austria. Doka then devised a customized solution based on their SKE-100 automatic climbing shutter system.

Engineering challenges:

Before undertaking the construction, there were several major challenges to be addressed namely

1. The foundations of the bridge included 604 large diameter shafts drilled to lengths of 6m to 34m ingeotechnical conditions that varied from highly weathered volcanic material to massive high strengthrocks.

2. The superstructure of the approach bridges were the heaviest spans in the country to be built with span- by-span method using overhead gantry through a series of vertical and horizontal curves.

3. A one-of-its-kind, diamond shaped 128m high concrete tower with flaring lower legs, converging upper legs, unified tower head housing the stays and a throughout varying cross section along the height of tower.

4. Erection of 20000 MT Bandra cable-stayed deck supported on stay cables within a very close toleranceof deviations in plan and elevation.

 

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