The Mumbai Trans Harbour Link, officially known as the Atal Bhari Vajpai Sewri Nhava Sheva Atal Setu, is a remarkable engineering marvel that has recently been completed in India. This awe-inspiring bridge, with a length of 21.8 km, stands as the longest sea-bridge in the country and the 10th longest in the world.
Construction and Design :
The Mumbai Trans Harbour Link is divided into three packages, and construction has been handled by eminent global engineering giants. These include Daewoo Engineering and Construction from South Korea and Tata Projects Limited from India. The joint venture between Daewoo and Tata Projects Limited is a proud partner in completing Package 2 of the project. This section covers the central part of the bridge and spans 7.8 km from Shivaji Nagar in Navi Mumbai to Mid sea, connecting to Package 1 and further extending to Mumbai.
The bridge is built using both concrete and steel deck components. The steel deck, known as the Orthotropic Steel Deck (OSD), is a technically advanced feature of the bridge. The OSD section measures 1.8 km, featuring the longest span of 180 m. The project required extensive planning and execution, taking into account three different geological zones: land, intertidal, and marine.
Key Features :
The Mumbai Trans Harbour Link Package 2 comprises of various key features. The interchange at Shivaji Nagar, Navi Mumbai, plays a crucial role in connecting Mumbai to the Navi Mumbai International Airport, Jawaharlal Nehru Port Trust (JNPT), and the Nana region. The interchange consists of six ramps, enabling smooth connectivity and reducing travel time for commuters.
The construction of Package 2 began in March 2018, with the establishment of a casting yard and a temporary access bridge for the intertidal section. The design of the bridge foundations considered the ground strata, incorporating pile foundations for the intertidal and marine sections, and utilising open foundations for the land and interchange sections.
Challenges and Accomplishments :
The construction of the Mumbai Trans Harbour Link Package 2 faced numerous challenges. The joint venture between Tata Projects Limited and Daewoo Engineering and Construction demonstrated exemplary planning and execution skills in navigating through heavy monsoons, tidal variations, cyclones, disruptions in supply chains due to the COVID-19 pandemic, and geopolitical shifts. The project successfully met the stipulated time frame of 5 and a half years, overcoming these challenges.
The numbers associated with the project are staggering. Builders used 3.6 lakh cubic meters of concrete and 64,000 metric tons of reinforcement steel in total. The project comprises 208 concrete spans, each measuring 60 m in length, constructed from pre-cast segments joined using 5,900 km of post tension strands. The steel section, constructed with orthotropic steel decks, enables large ships to pass underneath the bridge with ease, marking another notable achievement. Specialised facilities in Japan, South Korea, Myanmar, and Vietnam fabricated the decks. Workers assembled these modular panels into 32 spans, reaching a total weight of 38,000 metric tons.
Lifting and placing the OSD spans onto floating barges was a mammoth task. The joint venture successfully lifted and placed all the spans, including the heaviest one weighing 2200 metric tons and measuring 180 m in length. This required maintaining delicate balance between tidal variations, changing wind speeds, underwater currents, and seabed pipelines. Additionally, the project overcame unexpected challenges caused by the COVID-19 pandemic. They shifted launching girders of concrete spans from one side to the other in one single piece. They achieved this using a 100 m barge.
An Engineering Marvel :
Atal Setu, the completion of Mumbai Trans Harbour Link Package 2, has turned a fifty-year-old aspiration into a tangible reality. This project has set new benchmarks in terms of quality, safety, and environmental standards. It also showcases the global synergy and collaborative efforts among stakeholders, transcending geographic boundaries for a common goal.
The joint venture between Daewoo Engineering and Construction and Tata Projects Limited takes immense pride. They dedicate this modern engineering marvel to the nation. Atal Setu, a steadfast and stable bridge, stands as a historic icon, facilitating convenient commutes and connecting people and places. People will remember it for its stability, convenience, and the crucial role it played in connecting diverse communities and locations.