Samruddhi’s defining feat is India’s widest 8-km twin tunnel through the Ghats

Commuters currently using the Mumbai-Nashik Expressway must navigate the winding roads of Kasara Ghat. The stretch from Kasara to Igatpuri, covering 19 km, typically takes around 30 minutes, with vehicles climbing steep slopes through sharp bends.

A Dream Turns into Reality…
CM Devendra Fadnavis enjoyed a drive on the ‘Hinduhrudaysamrat Balasaheb Thackeray Maharashtra Samruddhi Mahamarg’ along with DCM Eknath Shinde and DCM Ajit Pawar.
This visionary project, and brainchild of CM Devendra Fadnavis himself, stands as a… pic.twitter.com/iItHRdw2c6

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The new twin tunnels, however, eliminates this strenuous journey. This twin-tube road tunnel, 8 kilometres in length and 17.61 metres in width, is the widest road tunnel in the country and the fourth longest by length. It reaches a height of 9.12 metres and allows traffic to bypass the steep Kasara Ghat, reducing travel time between Kasara and Igatpuri to just eight minutes.

According to MSRDC officials, the tunnel was constructed using the New Austrian Tunnelling Method (NATM), which involved excavation through solid rock.

Despite challenges posed by the COVID-19 pandemic and lockdowns between March 2020 and May 2021, the tunnelling work was completed within two years in October 2023.

Along with the tunnel, 17 valley type that span 10.56 km, 21.12 km for both lanes, were also built. The longest among them is 2.28 km, which is located just after the Igatpuri tunnel ends towards the Mumbai side. To make these viaducts, engineers needed to construct piers up to 84 metres high, all this with the persistent challenges of hard rock formations in the valley and adverse weather conditions.

The construction in narrow and windy valleys under monsoon conditions added safety issues for workmen, which was an additional responsibility for the MSRDC and other stakeholders. “Excavations 40 metres deep were needed in many places and the high wind velocities made working on higher levels extremely risky. But by exacting engineering and severe safety guidelines, the constructions were finished on time,” a senior MSRDC official told The Indian Express.

K Mallikharjuna Rao, business unit head, Hydro and Underground at Afcons Infrastructure Ltd, who carried out the work on the tunnel and viaduct for package 14 of the greenfield expressway said, “We faced unprecedented rainfall that took a toll on our tunnel construction as well as impeded our efforts at Viaduct-II. Due to heavy showers and dense fog, visibility remained an issue. However, we used the best safety practices to enable a safe work environment.”

Apart from the engineering marvel, the last phase has three new interchanges at Igatpuri, Khutghar and Amane facilitating regional connectivity for passenger as well as freight traffic. The opening of this section now makes the entire 701 km Samruddhi Mahamarg corridor open for public, putting Nagpur and Mumbai on an eight hour driving distance from each other.