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MRITYUNJAY BOSE

SCIENCE REPORTER, March 201029

The Bandra-Worli Sea Link is a marvel of

engineering technology and has also led to

considerable easing of traffic in Mumbai. IT is gigantic. It is majestic. It is anengineering marvel and anarchitectural wonder too. The first -of-its-kind in India (first bridge to

be constructed in open-sea conditions),the 5.6-km-long, eight-lane, approxi-mately Rs 1,600-crore Bandra-WorliSea Link (BWSL), which has now beenrenamed as the Rajiv Gandhi Sea Link,is an engineering marvel that aims toease traffic in Mumbai, Indiascommercial capital.

The construction is a miracle onthe Arabian Sea that has an imposingpresence on the Western horizon ofMumbai. One can imagine thestrength and might of the bridge giventhe fact that it weighs nearly 50,000African elephants and the length ofsteel wires used in the project isequivalent to the circumference of theEarth. And it has made the difference:the distance which earlier took nearly45 minutes from Bandra till Worli ifone uses the old road now takes justeight minutes.

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It is for the first time that cable-staybridges have been attempted on openseas in India. Coupled with the fact thatthe aesthetically designed pylons havean extremely complex geometry andone of the longest spans for concretedeck, the challenges encountered wereindeed formidable. With its cable-stayedtowers soaring gracefully skywards, the

bridge was constructed by HindustanConstruction Co Ltd (HCC), anengineering, construction, infrastructureand integrated urban development andmanagement giant and designed by UK-

based Dar Consultants for MaharashtraState Road Development Corporation(MSRDC). It has today emerged as oneof the prominent landmarks of Mumbaiand also a popular tourism destination.

HCC Chairman and ManagingDirector Ajit Gulabchand said:

Construction of the Bandra-Worli SeaLink has been one of the mostchallenging infrastructure projectsundertaken in recent times in India. Wetook on this project with the quest to setnew benchmarks in precisionengineering and prove Indiasinfrastructure development capabilities.Reflecting on the hard work of ourengineers and over 3000 workers whohave raised this Sea Link in rough opensea conditions, I am proud to say wehave truly built a monument to humanskills, enterprise and determination.

People Behind the Bridge

A to ta l of 2850 worker s and 150engineers were employed to work on theproject and, over a span of eight years, atotal 2,57,00,000 man hours wereutilised between 2001 and 2009.

Several teams of foreign engineersand technicians have been involved inspecialized tasks on the structure of thesea link. These include professionalsfrom China, Egypt, Canada, Switzerland,Britain, Serbia, Singapore, Thailand,Hong Kong, Indonesia and thePhilippines. In terms of language, culturaldifferences and methods of work thesekey people were different, yet theengineering challenges kept the groupcreatively involved.

Left above: Construction of the sealink in full flow;

Left below: A panoramic view of thebridge

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Says Mr. S. Srinivasan, Director of

Dar Consultants, UK, This cable-stayed bridge is the longest bridge inSouth-East Asia and certainly thelongest in India so far. The cable-stayed

bridge gives aesthetic appeal to thebridge.

Mr. Len Gower, a Canadian surveyexpert, who worked on evolved survey

methodology for complex geometry of

pylon said, I was working on a projectin China at that time and my friend fromIndia had sent me a picture of the cable-stayed bridge. The picture hooked meso much that I left the ongoing projectof Sutong Bridge and came to India. Ihave done nine projects and they allhave the same boring design. I wanted

to do something new, challenging and

interesting so I joined this project. Thissea link is technically challenging andaesthetically pleasing.

M.C. Bhide, veteran engineer andHonorary Director-General of theIndian Institute of Bridge Engineers(IIBE) referred to the BWSL as anengineering marvel and one of thebest projects in recent times.

A major chunk of steel forconstructing the bridge came from theSteel Authority of India Ltd (SAIL). As amatter of fact, each cable can bear a loadof 900 tonnes. The BWSL has gobbledup a total of nearly 22,235 tonnes of steel;SAILs share is pegged at over 13,780tonnes, according to SAIL officials.

The sea link begins at the MahimInterchange at the northern end and

joins Khan Abdul Gaffar Khan Road onthe Worli Sea Face at the southern end.The link connects Bandra to Worli by a5.6 km long bridge. The Sea Link isprimarily meant to provide analternative to the Mahim Causewayroute that is presently the onlyconnection between the south Mumbaiand the Western and Centralsuburbs.

The Link Bridgeconsists of twin

continuous concretebox girder bridgesections for trafficin each direction.Each bridge sectionexcept at the cable-stayed portion is

supported on pierstypically spaced at50 meters.

The Link Bridgeconsists of twin

continuous concretebox girder bridgesections for trafficin each direction.Each bridge sectionexcept at the cable-stayed portion is

supported on pierstypically spaced at50 meters.

FeatureArticle

Renamed Rajiv Gandhi Sea Link, the bridge is an engineering marvel that aims toease traffic in Mumbai, Indias commercial capital.

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The project was commissioned tooffer a quicker alternative to the north-south traffic that presently amounts tosome 125,000 cars a day in each directionand is expected to grow at the rate of 250cars per day. The eight-lane flyover hasa capacity of carrying about 1.40 lakhcars per day. Large multi-axle vehiclesand two-wheelers would not be allowedon the sea link. Speed limit would haveto be maintained at 100 km/hr.

Building ChallengeBuilding the Bandra-Worli Sea Linkwas a challenge indeed. The LinkBridge consists of twin continuousconcrete box girder bridge sections fortraffic in each direction. Each bridgesection except at the cable-stayedportion is supported on piers typicallyspaced at 50 metres. Each section ismeant for four lanes of traffic completewith concrete barriers and service side

walks on one side. The bridgealignment is defined with vertical andhorizontal curves.

The highlights of the Bandra-WorliSea Link are the two aestheticallydesigned cable-stayed bridges, viz., theBandra and Worli Cable-StayedBridges of 500 and 150 metre spans,respectively, with the highest towerssoaring to a height of 126 metres,equivalent to the height of a 43-storied

bu ilding . The ca ble- stayed desi gnallows free movement of fishing boats.

The cable-stayed portion of theBandra channel is 600 metres in overalllength between expansion joints andconsists of two 250 metres cablesupported main spans flanked by 50metres conventional approach spans.A centre tower with an overall heightof 128 metres above the pile cap levelsupports the superstructure by meansof four planes of stay cables in a semi-fan arrangement.

The cable-stayed portion of theWorli channel is 350 metres in overalllength between expansion joints andconsists of two 150 metres cablesupported main spans flanked by 50metres conventional approach spans.A centre tower with an overall height

Celebrating the opening of the bridge for traffic

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Adequate lighting levels have been maintained andenergy saving luminaries are installed.

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of 55 metres above the pile cap levelsupports the superstructure by meansof four planes of stay cables in a semi-fan arrangement.

According to Mr. Araby ELShenawy (Engineer and head of theProject Management Consulting teamfrom Egypt), The method of balancedcantilever was adopted for the

construction of the deck for BandraCable-stayed Bridge. This isconsidered to be one of the biggestcable-stayed bridges in the world withconcrete deck built with this methodof construction. It was therefore a realchallenge to monitor the behavior ofthe structure during all erection stagesand to compare the same with the

behavior of the corr es pondingtheoretical computer model of the

bridge, to ensure achievement of thedesired geometry at the end of theconstruction. It was also essential to

control the stresses in the criticalbridge elements during every singleconstruction stage to ensure theadequacy of the bridge elements all thetime.

Big Brother Watching!Security of the Bandra-Worli Sea Linkis a major issue. The Mumbai Police

has factored in the security concernsand has taken a series of measures byputting up a high-tech security system.A special team of officers led by JointCommissioner of Police (Traffic)Sanjay Barve monitored the trafficflow several times. CCTV camerashave been installed on the sealink atseveral places. Underneath the bridgealso security gadgets have beeninstalled.

Continuous Power SupplyFor the entire project, a reliable anddependable power supply has been

arranged. It will also house dieselgenerator sets and auto mains failurepanels to cater to critical load e.g.monitoring, surveillance, andcommunication equipment emergencyservices like aviation obstructionlights. Adequate lighting levels have

been maintained and energy savingluminaries are installed.

Special emphasis has been givento incorporate lighting protection at

br idge tower and contro l roombuilding to protect those buildings/structures and the sophisticated

monitoring and communicationequipment installed therein. A built-infeature of providing reliability andavailability of equipment is achievedthrough duplicate cables for suchequipment. Facade lighting for bridgetower and special lighting in landscapedarea is also included.

Mr Mrityunjay Bose works with Sakaal Times asits Special Correspondent in Mumbai. Address: 102,A-Wing, VK Tower, Evershine City, Vasai (East),Thane District401208.E-mail: mrityunjaybose@gmail.com

Bulky EquipmentConstruction of the mammoth bridgestructure required some huge cranes and

several other equipments. Some of theseincluded Jack-up platform, floatingbarrages, boats, crawler crane, towercrane, gantry crane, derrick crane,launching truss, placer boom, dieselgenerators, diesel & air compressors,concrete pump, transit mixers, reversecirculation drilling machine & A framebarrage.

The equipment was broughttogether from various countries. A totalof 130 equipments were used and thecost was Rs 190 crore. Twenty-fiveequipments were imported at a cost of

Rs 78 crores.

One can imagine the strength andmight of the bridge given the factthat it weighs nearly 50,000 Africanelephants and the length of steelwires used in the project isequivalent to the circumference ofthe Earth.

The link connects Bandra to Worli by a 5.6 km long bridge.

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