Atal Setu and the science behind it: An engineering marvel in Mumbai

Prime Minister Narendra Modi inaugurated the Mumbai Trans Harbour Link (MTHL), also known as Atal Setu, on Friday, marking the country's longest sea bridge. It is expected to reduce the travel time between South Mumbai and Navi Mumbai from two hours to just 20 minutes.

The 21.8-kilometre-long bridge, constructed at a cost exceeding Rs 17,840 crore, stands as a testament to Indian engineering brilliance.

Apart from its transformative impact on the everyday lives of residents of Mumbai, Atal Setu is a scientific marvel.

Here's a look into the science behind the bridge::

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EARTHQUAKE RESISTANCE

Atal Setu incorporates 254 seismic isolation bearings, acting as a buffer between the bridge deck and the supporting piers. During an earthquake, these bearings allow the deck to move independently, absorbing tremors and protecting the structure.

Specially designed ductile concrete piers bend instead of breaking under stress. This flexibility helps dissipate earthquake energy without damaging the bridge.

HIGH-PERFORMANCE CONCRETE

The high-performance concrete blend used in bridge construction withstands the corrosive onslaught of seawater and the relentless Mumbai sun. Its low heat generation minimises cracking and ensures long-lasting durability.

PRECAST SEGMENTS

The bridge deck comprises precast concrete segments, manufactured off-site and assembled with precision. This rapid construction technique minimises disruption and ensures consistent quality.

CAISSON FOUNDATIONS

Caisson foundations play a crucial role in sea bridge construction, providing stable support amid challenging marine conditions.

The Atal Setu utilises this mechanism in its construction. Caisson foundations work by providing a stable, watertight support structure for sea bridges.

UNDERWATER CONSTRUCTION

Building underwater is one of the toughest tasks in constructing this massive bridge. Skilled divers and advanced equipment like remotely operated vehicles (ROVs) were used in constructing the bridge's pylons and foundations.