Amid reports raising questions on why under-construction Silkyara tunnel in Uttarkashi did not have a separate escape tunnel, the government on Wednesday said a separation wall was provided in the tunnel with egress openings at regular intervals that could be used as an escape route during an emergency.

The 41 workers, who were trapped in the tunnel from November 12, were rescued on November 28.

In a written reply to a question in the Rajya Sabha, Union Road Transport and Highways minister Nitin Gadkari said, "In the Silkyara bi-directional tunnel on Dharasu-Yumunotri highway (NH-134), a provision of separation wall has been provided at the centre of the carriageway along with egress openings at an average interval of 565 metres for vehicular crossover and at an average interval of 300 metres for pedestrian cross passage for escape purposes during the emergencies."

Gadkari was asked whether the government has conducted a probe as to why Navayuga Engineering Company Ltd (NECL) did not build a rescue route, as is the norm in tunnel construction.

The National Highways and Infrastructure Development Corporation Ltd (NHIDCL) is constructing the tunnel through Hyderabad-based Navayuga Engineering Company Ltd.

Silkyara tunnel is a single-tube tunnel and is divided into two inter-connected corridors by a partition wall.

Each inter-connector corridor can work as an escape passage for the other.

On whether the government had reviewed safety norms after the collapse of the tunnel in 2019, the minister said the Silkyara tunnel on the Dharasu-Yumunotri highway (NH-134) is being built under the Engineering, Procurement and Construction (EPC) mode, wherein the design responsibility lies with the EPC contractor.

"After encountering minor spalls/falling of debris-forming cavities during construction in 2019, the construction sequences and primary support system are reviewed from time to time on the basis of actual ground behaviour observed and are approved by authority's engineer engaged for the project, which are executed under the supervision of officials of NHIDCL," he added.

The minister said on the intervention application filed by the Ministry of Defence, the Supreme Court in 2021 permitted widening of the three strategically important National Highways -- Rishikesh-Mana (NH-7), Rishikesh-Gangotri (NH-34) and Tanakpur-Pithoragarh (NH-9) -- to two-lane with paved shoulder (10-metre wide pavement) under Char Dham Pariyojana.

The 4.5-kilometre Silkyara tunnel project in Uttarakhand, which is part of the Centre's strategic 900-km 'Char Dham Yatra All Weather Road', aims to improve connectivity to four holy towns of Yamunotri, Gangotri, Kedarnath, and Badrinath in Uttarakhand.

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