Nearly 27 per cent of the project related work in the Mumbai Trans Harbor Sealink (MTHL) has been completed said Mumbai Metropolitan Region Development Authority (MMRDA) on Wednesday.
With this, it has achieved a significant milestone in the project that costs Rs 14,200 crore. In the recent developments that took place, MMRDA also mentioned about the delivery of first Orthotropic steel deck (OSD) which will lessen deck related on-site activities.
According to the MMRDA, in MTHL, OSDs are being used for spans upto 180 metres without any cable stays/ suspensions. "It is extremely difficult to achieve similar spans with concrete bridge without cable supports. Therefore, the prefabricated steel deck lessens the deck related on-site activities enabling parallel and faster construction work," said the MMRDA official.
Of the total length of MTHL bridge of 22km, the length of OSD superstructure is about 4.1 km. The width of steel superstructure is about 15.8m for each carriageway. The total steel quantity to be used for OSD superstructure in the project will be about 85,000 metric tone. The launching of OSD span superstructure is expected to start in April 2021.
The steel spans are fabricated in fabrication workshops facilities located in Japan, South Korea, Vietnam, Taiwan, Myanmar etc. Final assembly, load-out and raising of the deck will be carried out in India, informed MMRDA.
What is OSD?
Orthotropic Steel Decks (OSD) typically has hollow box geometry, unique rib stiffening system and fabricated deck consists of a structural steel deck plate stiffened either longitudinally with ribs or transversely, or in both directions resulting in less overall weight of superstructure for long spans as compared to other bridge types. Lower superstructure mass also means lower seismic forces during an earthquake event. Lighter superstructure weight helps in optimization of the foundation and substructure design in seismic prone areas.