A version of this article originally appeared in Construction World

Rescue teams faced challenges reaching 40 workers trapped in a collapsed highway tunnel in the state of Uttarakhand in India. Officials reported that massive boulders were impeding efforts to establish an evacuation passage.

Despite the tunnel collapse three days ago, the trapped workers remain safe and healthy, according to an official involved in the ongoing rescue operations, as the workers have been provided with food, water, and oxygen through a pipeline since the incident occurred 5:30 AM on Sunday.

To address the blockage caused by boulders, G.S. Naveen, the relief commissioner of Uttar Pradesh state, stated that a heavy machine from New Delhi is being brought in to insert a new evacuation pipe.

The 4.5-km tunnel, part of the Char Dham Hindu pilgrimage route in neighboring Uttarakhand state, collapsed during the night shift with approximately 50 to 60 workers present. Reports suggest that those near the tunnel exit managed to escape, leaving 40 workers trapped deeper inside.

The Char Dham highway, a significant project of Prime Minister Narendra Modi's government, aims to connect four revered Hindu pilgrimage sites in Uttarakhand through a network of roads spanning 890 km and costing $1.5 billion.

The mountainous region's susceptibility to landslides, earthquakes, and floods has raised concerns. This incident adds to previous instances of land subsidence attributed by geologists, residents, and officials to rapid construction in the mountains.

Criticism from environmental experts has prompted temporary halts in the project, particularly after hundreds of houses were damaged by subsidence along the routes. The tunnel project, initiated in 2018 with an initial completion target of July 2022, now faces a delay, with the government stating a revised completion date of May 2024.