Thackeray, along with top officials of Mumbai Metropolitan Region Development Authority and others, will launch the girder at the Mumbai-end of MTHL in Sewri.
The girder, weighing 1,000 tonnes, will be set off by a launching girder with a capacity of 1,400 tonnes, and mark the erection of the first span in the MTHL.
The MTHL, the second road link cutting through the Arabian Sea in the island city's eastern coast to join the mainland between Sewri and Chirle respectively, is expected to be completed by 2022.
Estimated to cost Rs 18,000-crore, work on the six-lane plus two emergency lanes, 27-metre-wide bridge project began in April 2018 and will attract over 70,000 vehicles plying on it daily when thrown open to traffic.
The total bridge will be 22 kms long with 15.5 kms running in the sea, with interchanges on both sides, making it the longest sea-bridge in India, and second after the Rajiv Gandhi Bandra Worli Sea Link, which is now being extended upto Andheri.
Financed by a loan from the Japan International Cooperation Agency (JICA), the MTHL will be connected to the new international airport coming up in Navi Mumbai and the country's first expressway, the Mumbai-Pune Expressway.
With around 19 percent financial progress achieved, the project is being executed in three packages by three contractors with one intelligent transport system since March 2018.
The MMRDA will install 'noise' and 'vision' barriers on a 6-km stretch of the MTHL, first to block the view of the sensitive BARC nuclear complex and the other to protect the movement of flamingos and other migratory birds at the Sewri mudflats, besides silence zones on both sides.
The work of piling and pier construction is currently underway along with constructing a temporary bridge with casting of segments.
Conceived over 45 years ago, the project was finally cleared by then Chief Minister Prithviraj Chavan in 2012 and after securing all clearances, Prime Minister Narendra Modi had laid the foundation stone for MTHL in December 2016.
( With inputs from IANS )