DEHRADUN/UTTARKASHI: With 40 workers trapped in the Silkyara tunnel for over 150 hours, experts have now started raising safety concerns in the construction of the passage built under the Char Dham road project."As a norm, escape routes should be there in such long tunnel projects to facilitate rescue work in case of an emergency," PC Nawani, former director of Geological Survey of India, told TOI on Friday."Moreover, in the case of the 4.5km-long Silkyara tunnel, extra support through available instruments should have been provided on the identified soft/loose part of the mountain," said Nawani.

He added: "Companies and agencies involved in tunnel construction in India tend to overlook safety concerns and measures suggested by geologists.

Principles of New Austrian Tunnelling Method, which is both a construction method and a design philosophy, are also not followed in the true sense."Senior geologist SP Sati added that the whole region where the tunnel is being built is a fragile zone, with fractured rocks.

Another expert, requesting anonymity, pointed out that "in the absence of an escape route, workers are facing the challenge of a contaminated environment as gases generated underground are not being channeled out."Mrityinjay Kumar, a worker from Bihar who has been on the project since its start in 2018, raised similar safety concerns.Meanwhile, Bernard Gruppe, a company based in Europe, which provided detailed design services to Navayuga construction firm for the Silkyara-Barkot tunnel project, said, "Since the start of tunnel driving, geological conditions proved to be more challenging than predicted in the tender documents."Notably, chief minister Pushkar Singh Dhami has announced a "safety review of all ongoing tunnel projects in Uttarakhand".