ITA president Arnold Dix arrived in Uttarakhand at the weekend and, as the rescue operation entered its ninth day, he confirmed to T&TI that several options were being considered, including vertical shafts.

“Preparations for vertical options are under way,” he said, adding that “multiple concurrent options”, including horizontal access, were being considered.

Initial efforts to create an escape route by jacking a 900mm-diameter pipe through the collapse debris – and also to excavate with an 800mm auger – failed because boulders blocked the auger.

A jacked 120mm diameter steel pipe has enabled workers to be supplied with food, water and oxygen.

Geology in the Himalayan region is very complex and the rescue operation is encountering a mixture of soft ground and hard boulders.

The 4.5km Silkyara Bend-Barkot Tunnel is being developed for National Highways and Infrastructure Development Corporation (NHIDCL) to provide an all-weather route and reduce travel distance by about 20km between Dharasu and Yamunotri.