Trusses set to carry sea link story forward

The two launching trusses each weighing around 1200 metric tonnes have been critical in the segment-by-segment construction of the 5.5-km sea link. The 110-metre long trusses that are owned by Hindustan Construction Company (HCC) were custom-built to lift a total of 2,342 per-cast segments for the super-structure of the BWSL.

“The launching trusses have been the most important equipment used for construction of the super structure or deck of the bridge. The launching trusses that are custom built for precast segment construction can be used for similar comparable projects,” said D K Sharma,chief engineer of HCC for BWSL.

Asked whether the trusses can be used for the Worli-Haji Ali Sea Link,chief engineer of Maharashtra State Road Development Corporation S M Sabnis said,“It (launching truss) can probably be used depending on the method of construction.”

The precast concrete segments of the BWSL were fabricated at the Bandra construction site and carried on a barge to the construction site and then lifted by the launching truss to the designated height to assemble between two pillars of the sea link,each 50 metres apart. Fifteen such segments were fitted between two pillars and the launching truss was built to lift all 15 segments at a time,each weighing 130 tons. Once these segments were fixed between two pillars,the truss could crawl forward to the next pillar with its mechanical legs and state-of-the-art hydraulics. The truss also has the capacity to align the total span weighing approximately 2000 MT in hanging condition after the application of the epoxy adhesive is completed. The world’s biggest floating cranes,the Asian Hercules,lifted the 1260 ton launching truss to shift it to the Worli side of the cable-stayed portion in November 2006.

The Asian Hercules crane was mounted on a barge which was over 240-ft long and more than 130-ft wide,weighs 5,900 tons and has enough lifting capacity (1600 MT) to lift the launching trusses.