The partial collapse of the Silkyara-Barkot tunnel in Uttarkashion on November 12 that held 41 workers for 17 days before their rescue on Tuesday was not an unusual incident.

Indeed, the 4.5 km-long two-lane bidirectional tunnel, the longest on the Char Dham all-weather road project, has been subjected to a series of similar incidents during the previous five years.

Anshu Manish Khalkho, a director at NHIDCL, the company managing the project, told TOI that roughly 19-20 minor to moderate collapses happened during construction.