The Uttarakhand tunnel disaster was caused by a 'shear zone' situation, with no escape route or piped passage in place. The tunnel collapsed on November 12 and an expert committee was established on November 14. The 'shear zone' likely missed during inspections before drilling began. The 4.531 km '2-Lane bi-directional Silkyara bend-Barkot tunnel with escape passage' was approved in February 2018 to provide 'all weather connectivity' to Yamunotri, part of Uttarakhand's Chardham Yatra.
