The Bandra-Worli Sea Link is a cable-stayed bridge that connects Bandra in the western suburbs of Mumbai to Worli in south Mumbai. It is part of a larger project to upgrade road transportation in Mumbai. The bridge consists of twin box girder bridges supported by piers and cable-stayed portions with towers. It was constructed using precast concrete segments erected by a large floating gantry crane. The construction faced challenges from marine conditions, variable geology requiring pile foundations, and erecting very heavy spans for the approach bridges.

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BANDRA-WORLI SEA LINK
ABSTRACTION:
The Bandra-Worli Sea Link (BWSL) is a civil engineering marvel spanning an arc of the
Mumbai coastline. With its cable-stayed towers soaring gracefully skywards, the sea link is a
reflection of the modern infrastructure that Mumbai is adding in its progress towards
becoming a world-class city. That links Bandra in
the WesternSuburbs of Mumbai with Worli Suburbs of Mumbai with Worli in South
Mumbai. The bridge is a part of the proposed Western Freeway that will link the Western
Suburbs to Nariman Point in Mumbai's main business district. India's first bridge to be
constructed in open-sea conditions. Engagement of Asian Hercules, one of the largest floating
shear leg cranes in the world for shifting 1,260 MT launching truss from Bandra end to Worli
end of the main cable stay bridge.

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INTRODUCTION:
The Bandra Worli Sea Link is a civil engineering marvel spanning an arc of the Mumbai
coastline. With its cable-stayed towers soaring gracefully skywards, the sea link is a
reflection of the modern infrastructure that Mumbai is adding in its progress towards
becoming world claa city.
The project is a part of the Western Freeway Sea Project, which, in turn, is a part of a
larger proposal to upgrade the road transportation network of greater Mumbai. In the first
phase it will connect Bandra to Worli where as in the subsequent phases the plans are to take
it further to Haji Ali and then to Nariman Point. It is a connecting bridge linking the city of
Mumbai with its western suburbs and has the potential to bring about permanent and far
reaching changes in the travel patterns of the area. The Bandra Worli Sea Link is primarily
meant to provide an alternative to the Mahim Causeway route that is presently the only
connection between the south Mumbai and the Western and Central suburbs. The project
starts from the interchange at Mahim intersection, i.e. intersection of Western Express
Highway and Swami Vivekanand Road at the Bandra end, and connects it to Khan Abdul

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Gaffar Khan Road at the Worli.
Until now, Mahim Causeway, the North-South connector between the western suburbs and the
island city of Mumbai getting increasingly bottleneck prone. It takes commuters nearly an hour to
travel the 8 km distance from Mahim to Worli. The Bandra Worli Sea Link will increase the route
options of passengers travelling from the island city to the western suburbs and vice-versa and thereby
decongest the overstrained Mahim Causeway and western corridor. The Link 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 meters. Each section 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.
Form
The main cable stayed section of the bridge spans 600m in length, consisting of two 250m
cable supported spans and two 50m conventional approach spans. The smaller cable stayed
section is 350m in length and comprises of 2 smaller cable stayed sections with a 150m
central span and 2 50m approach spans on either side. The design is described as follows by
the designer. “The overall tower configuration is an inverted "Y" shape with the inclined legs
oriented along the axis of the bridge” In total there are 264 cables attached to the towers, they
form a semi-fan arrangement. The bridge deck is constructed of pre cast box girder sections
which are identical those used for the approaches “the bridge is proposed to be built utilizing
the concept of precast, post - tensioned, twin segmented concrete box girder sections”

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Layout
Inverted Y shape
CONSTUCTION:
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 :-
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 Plaza on the Bandra side and a public promenade

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Package IV: Construction of Cable-Stayed Bridges together with viaduct approaches
extending from Worli up to 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. Main features of
this technically challenging package are :
 Cable-Stayed Bridge including viaduct approaches extending from Worli up to Toll
Plaza at Bandra end
 Modern Toll Plaza
The work under this package was awarded to HCC.
Details of Package - IV
Main Bridge Structure
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 meters. Each section 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 three different parts:
 Part 1 - The north-end approach structure with Pre-Cast (PC) segmental construction.

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 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 meters each.
Expansion joints are provided at each end of the units. The superstructure and substructure
are designed in accordance with IRC codes. Specifications conform to the IRC standard with
supplementary specifications covering special items. The foundation consists of 1.5 meters
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 the superstructure of the precast segments. The Pre-Cast
segments are joined together using high strength epoxy glue with nominal prestressing
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. The segment weights vary from 110 tons to 140 tons per segment.
The segment length varies from 3000 mm to 3200 mm. Deck post tensioning is performed at
the completion of the erection of each 50m bridge span.

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Part- II Cable-Stayed Bridge
The cable-stayed portion of the Bandra channel is 600 meters in overall length between
expansion joints and consists of two 250-meter cable supported main spans flanked by 50
meters conventional approach spans. A centre tower, with an overall height of 128 meters
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 meters along the bridge deck.
The cable-stayed portion of the Worli channel is 350 meters in overall length between
expansion joints and consists of one 150 meters cable supported main span flanked by two 50
meters conventional approach spans. A centre tower, with an overall height of 55 meters,
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 meters along the bridge deck. A total

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of 264 cable stays are used at Bandra channel with cable lengths varying from approximately
85 meters minimum to nearly 250 meters maximum. 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. A total of
160 cable stays are used at Worli channel with cable lengths varying from approximately 30
meters minimum to nearly 80 meters maximum The foundations for the main tower comprise
2 meter-drilled shafts of 25 meters length each. Cofferdam and tremie seal construction have
been used to construct the six-meter deep foundation in the dry. The superstructure comprises
of twin precast concrete box girders with a fish belly cross sectional shape, identical to the
approaches.

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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. similar to the North
end approach structure in construction methodology with span by span match cast concrete
box girder sections.Similar to the north end approach detailed, access ramps are provided for
connection to the western freeway i.e. extension upto Nariman Point. A total of about 160
stay cables required for the cable - stayed spans at Worli channel with cable lengths varying
from approximately 30 meters minimum to nearly 80 meters maximum. "I" shape tower
configuration with the inclined legs. Tower cable anchorage's 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.

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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 drivers to make
cash payment to a toll attendant, and stopping for cash exchange.
Power Supply Distribution and Road Lighting System
A reliable and dependable power supply has been arranged for the entire project. It will also
house diesel generator sets and auto mains failure panels to cater to critical load, e.g.,
monitoring, surveillance and communication equipment emergency services like aviation
obstruction lights. Special emphasis has been given to incorporate lighting protection at
bridge tower and control room building to protect those building/ structures and the
sophisticated monitoring and communication equipment installed therein.
Challenges encountered during execution of the project:
Engineering challenges:

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BWSL Project is a unique and pleasing structure, but before undertaking the construction,
following were the major challenges to be addressed:-
 The foundations of the bridge included 604 large diameter shafts drilled to lengths of
6m to 34m in geotechnical conditions that varied from highly weathered volcanic
material to massive high strength rocks.
 The superstructure of the approach bridges were the heaviest spans in the country to
be built with spanby-span method using overhead gantry through a series of vertical
and horizontal curves.
 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.
 Erection of 20000 MT Bandra cable-stayed deck supported on stay cables within a
very close tolerance of deviations in plan and elevation.
The challenges were varied and started right from the Pre-Cast yard.
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 geology consists of basalts, volcanic tuffs and breccias
with some intertrappean deposits. These are overlain by completely weathered rocks and
residual soil. The strength of these rocks range from extremely weak to extremely 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 coarse grained conglomerate. The top

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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 as follows:
1. Highly variable geotechnical conditions of the foundation bed as explained above.
2. Highly uneven foundation bed even for plan area of one pile.
3. Presence of Intertidal Zone (Foundation Bed exposed in low tide and submerged
in high tide).
The key to success was a program of pier by pier in-situ testing. An extensive
subsurface exploration and drilling program (total 191 bores inside sea) was undertaken to
define the subsurface stratigraphy, determine the rock types and obtain material properties for

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optimizing the foundation design. Owing to a highly variable geology, the design calculations
were performed on a pier-by-pier basis and the unit side shear values were checked that they
did not exceed the load test results under similar rock conditions. The working load on the
approach piles ranges from 700 tons to 1500 tons whereas for the piles below the cable-
stayed bridge working load is 2500 tons.
For conducting the load test on the piles, the load to be applied varied from 4500tons to
9600tons. Arranging reactions for such loads either by normal kentledge method or by soil
anchor required massive scale arrangements in the sea waters. This was completely avoided
by a careful planning of load test using the Osterberg load cell method (Refer sketch 1).
in the
intertidal zone. This water head loss leads to very slow production rate and very high
consumption of drill bits. To overcome this problem, pits were made in the low tide at each
foundation location using an Excavator and the casing was placed at the bottom of the pits.
Then the casing was placed in the pits and was concreted to make an artificial penetration,
maintaining the proper water head for continuous drilling.

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For several locations, cofferdam construction using steel liner and sheet piles, was not
possible due to very hard and uneven strata. Here the problem was solved using circular steel
caissons. These caissons were fabricated outside and towed to location using A-frame barge.
The caissons were sunk at the location using counterweights. The unevenness at the bottom
was sealed using the gabion method. The benefit of this method was that it completely
eliminated deployment of resources like Jack up Platform, Crane, Vibrohammer,
Compressor, etc for liner pitching. It also eliminated substantial amount of field works and is
pre-fabricated in principle. completely eliminated deployment of resources like Jack up
Platform, Crane, Vibrohammer, Compressor, etc for liner pitching. It also eliminated
substantial amount of field works and is pre-fabricated in principle.
2. Superstructure:
The BWSL Project has (9+2) approach bridge modules. These modules range from 3
continuous span units to 8 continuous span units. The deck of the carriageways consists of
triple cell precast box girders supported on piers founded on independent substructure. The
Concrete Grade for the superstructure is M60. The average weight of the span is 1800 tons,
whereas the heaviest span in the bridge (to be erected with the Launching Gantry) weighs
2000 tons. In addition, the trusses were to be designed to receive the segment from the
already erected deck as well as from barges parked directly under the truss.
The Technical Data for the superstructure is as follows.
Max Longitudinal Gradient = 1.72%

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Max Crossfall = 6%
Max Radius in Plan = 600m
Min Radius in Plan = 246m
Typical Span Length = 50m and 30m in Link Bridge
Max Span Weight = 2000 tons
The erection gantry is 1260MT truss designed to erect spans for the above
configuration. A Typical 50m span of the approach bridges comprises 15 field segments, a
Pier segment and 200mm (nominal) insitu wet joints. During the span construction, all field
segments are suspended from the Gantry, glued and temporarily stressed together. Once the
gluing operation is completed, span alignment to the Piers is followed.After alignment, the
wet joints are cast including grouting of bearings top plinth. Once the wet joints achieve the
required strength, stressing of longitudinal PT is commenced followed by load transfer of
span to pires.

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Sketch - Erection Gantry Operation
Relocation of Launching Trusses using 1600MT capacity Barge Mounted Crane - Asian
Hercules
After the successful erection of the deck on Bandra side, the trusses were required to be
shifted across the Bandra cable stay bridge by 600 meters to Worli side to take up the spans
beyond the Bandra Cable Stay. Various options like (i) dismantling of the trusses at present
locations and reassembling them at new locations, (ii) lowering the trusses on a suitable
floating craft and shifting and erecting them, and (iii) shifting the total truss using a floating
crane, etc were analyzed in detail.
Asian Hercules is one of the biggest floating shear leg cranes in the world. This crane is
mounted on a barge which is over 240 feet long and more than 130 feet wide, weighs 5,900
tons and has enough lifting capacity (1600 MT) to lift a weight equal to 2,000 small cars. It
started its voyage from Singapore on October 9, 2006, and arrived at Mumbai's shores on
October 27, 2006. After obtaining the necessary regulatory clearances, it commenced
operations from November 06, 2006, including trial runs and realignments in its settings.
Selection of equipment was done considering various challenges, like the draft and space
available at working locations, tide limitations, and other weather constraints.
Cable Stay bridges
It is for the first time that cable stay bridges have been attempted on open seas in India.
Coupled with the fact that the aesthetically designed pylons have an extremely complex
geometry and one of the longest spans for concrete deck, the challenges encountered were
indeed formidable.

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Construction of 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:
 The section decreases gradually with height;
 There are horizontal grooves at every 3m height and vertical grooves for circular
portion that requires special form liners as well as it requires attention for de-
shuttering;
 The tower legs are inclined in two directions, which creates complexities in alignment
and climbing of soldiers;

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 Construction joints permitted only at 3m level. Inserts were permitted only in
horizontal grooves provided at 3m height.
On not being able to get immediate solution from reputed worldwide 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 affect further reduction in time cycles, HCC approached Doka, Austria. Doka then
devised a customized solution based on their SKE-100 automatic climbing shutter system.
Silent features & Engineering marvel:
 The project has already been acclaimed by the viewers as an engineering marvel of
modern India.
 First Cable-Stay Bridge in India in open sea.
 The length of the bridge is 63 times the height of the Qutub Minar in Delhi.
 Its weight is equivalent to 50,000 African elephants.
 The length of the steel wires used is equivalent to the circumference of the earth.
 The height of the cable-stayed tower is 128 m, which is equal to a 43-storey building.
 A total of 424 cables were used for both Bandra cable stay as well as Worli cable stay
bridges.
 The cables have been sourced from Shanghai Pujyang Cable Company, China. The
cables were subject to aseries of quality and engineering tests to meet the special
requirements including fatigue tests of twomillion cycles.
 The cables are made of high tensile steel and are designed to take the maximum load
of 900 tons.
 92,000 tons of cement was utilized to make BWSL.

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 Environment friendliness was top priority during the construction – fly ash, a waste
product extracted from thermal power plants, was mixed with concrete, to make the
construction durable as well as eco-friendly, thus making good use of waste material.
 The construction team is like a mini United Nations: several teams of foreign
engineers and technicians have worked on specialized tasks on the structure; these
include professionals from China, Egypt, Canada, Switzerland, Britain, Serbia,
Singapore, Thailand, Hong Kong, Indonesia and the Philippines, Australia.
 Given the gigantic size of the project, mega equipments were used in construction;
bringing them to the project site and operating them was a feat in itself. Asian
Hercules, one of the biggest floating shear leg cranes in the world, was hired from
Singapore to lift the massive 1250 tonnes, custom-built Launching Trusses with its
mechanical arm and relocate them on the Worli side of the bridge.
Benefits of project
• Savings in vehicle operating cost to the tune of Rs.100 crores per annum due to reduction in
congestion in the existing roads and lower vehicle operating cost on the bridge.
• Considerable savings in travel time due to increased speed and reduced delays at
intersections at existing roads.
• Ease in driving with reduced mental tension and overall improvement in the quality of life.
• Improvement in environment especially in terms of reduction in carbon monoxide, oxides
of nitrogen and reduction in noise pollution in areas of Mahim, Dadar, Prabhadevi and Worli.
• Project to have no adverse effect on fisheries, marine life and livelihood of fishermen.
• Reduced accidents.
• Proper landscaping measures along the approaches and promenade along waterfront to
enhance environment of the area.

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Disadvantages:
 Mangrove cover is drying up due to paucity of flushimg by tidal water.
 The blocking of tidal water near the mouth of mahim ceek has already resulted in
changes on level of sea water in the area.
 The size of mangrove has reduced to 50 percent of its original size in last few years.
 Land reclamation and construction of a bond for the bandra worli sea link in down
stream region of mahim creek has caused erosion along worli shoreline, endangering
the lives of thousands of fisher man – sag on recent ecological assement.
CRITICISM
 The Bandra-Worli link is a short stretch that does not even cover the western shore,
 As envisaged two decades ago. It took ages because of design changes and payment
disputes. The trans-harbour bridge creek has been bid for twice yet not awarded to
anybody.
 The entry to the bridge from mahim causeway to the bridge is approx a little more than
1.5 kms and the exit to old passport office is another 1 km. So the total length of the
bridge from Mahim to Worli is more than 7.1 kms, plus a toll fee of Rs 50/- on one time
use. The total length from Mahim to Worli is 5.2 kms.
 So they make a new road for us which is more expensive to travel then the old one
and longer too. The amount of time taken from Mahim to Worli is usually 25 mins in
the morning.
 While, The time taken to enter the BWSL and get out at worli seaface is 15 mins
because of the toll etc.. The T junction at Worli is senseless and will cause a lot of
trouble once more people start using the Sea link.

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Conclusion:
With technology from across the world, engineers from seven countries and workers from
across India, the Bandra Worli Sea Link rises above the Arabian Sea. The new Bandra-Worli
Sea Link is a symbol of the great advances of the economy and engineering capabilities
of the Indian subcontinent – not only because it is the sort of structure that could grace the
skyline of anymajor city, but due to the involvement of developing local manufacturing
which can compete with the world’sbest in the supply of complex structural components,
another thread in the tapestry of the region’s remarkable ongoing development as a
powerhouse of the world economy.

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References:
"Bandra-Worli sealink named 'Rajiv Gandhi Sealink'". The Times of India. 8 July 2009.
Retrieved 23 August 2009.
"Sonia opens Bandra-Worli sea-link, to be named after Rajiv". ZeeNews.com.
Retrieved 31 August 2010.
b "Bandra-Worli sealink opens midnight". The Times of India. 30 June 2009.
Retrieved 31 August 2010.
"Bandra Worli, Scribd". Scribd.com. Archived from the original on 8 August 2010.
Retrieved 31
"Finally, a date set for opening of Bandra-Worli sea link". The Indian Express. 11 June
2009. Retrieved 11 June 2009.
b Mid-Day Mumbai (31 March 2015). "Mumbai: Bandra-Worli Sea Link toll to increase
from tomorrow". Mid-Day Mumbai.
"Refer to Package IV – Project Status". Bandraworlisealink.com. 1 July
2009.Archived from the original on 24 July 2010. Retrieved 31 August 2010.
"Bandra-Worli sea link extended up to Haji Ali". Business Standard. 16 May 2008.
Retrieved 31 August 2010.
Chittaranjan Tembhekar (2 October 2009). "Sea link finances cause concern – Mumbai
– City – The Times of India". The Times of India. Retrieved 3 August 2010.
<http://www.youtube.com/watch?v=DVJGxnfrWno>

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b "Looking back: Frustration and elation of building the Bandra Worli Sea Link – Slide
5". DNA India. 30 June 2011. Retrieved 8 September 2011.