The Silkyara tunnel in Uttarakhand had design flaws that led to its collapse, a panel set up to investigate the incident has said.
The tunnel's design report lacked detailed geotechnical and geophysical investigations, the investigating panel wrote in its 70-page report.
“Prioritising safety measures is paramount in tunnel construction projects,” the media report quoted the findings of the probe panel as saying.
“There was no escape route and an alarm system in case of (a) tragedy. Even monitoring was not proper," said, Shantanu Sarkar, Director of Uttarakhand Landslide Mitigation and Management Centre.
Up to 41 workers were trapped in desperate conditions for 17 days after a section of the 4.5km tunnel collapsed in November last year.
The workers were pulled out of a thick wall of rubble under the tunnel by hand, using the primitive rat-hole mining method.