Expert Expressions
Dr CP Rajendran
The writer is an adjunct professor at the National Institute of Advanced Studies, Bengaluru and a director of the Consortium for Sustainable Development, Connecticut, US
A road tunnel, which was under construction in the Himalayan state of Uttarakhand, collapsed in the early hours of Sunday (Nov 12) after a landslide. Around 40 migrant labourers remained trapped 200 metres within the tunnel when part of the roof collapsed, blocking the tunnel entrance with concrete rubble, rocks, and twisted metal. The fate of the men inside the tunnel was hanging by a thread, despite massive rescue efforts.
The 5-km-long tunnel was being constructed on the Brahmakhal-Yamunotri road in the district of Uttarkashi as part of the Char Dham road project. It was inaugurated by Prime Minister Narendra Modi in 2016. This 12,000 crore flagship programme is conceived for the swifter movement of traffic to four religious shrines: Kedarnath, Badrinath, Yamunotri, and Gangotri in Uttarakhand, This project aims to increase the width of the Char Dham route to a double lane with paved shoulders of 12-m formation width.
The independent experts who are not on the payroll of the government raised red flags against this proposition, asking for a reduction of road formation width to 7.8 m. The 12-metre width road will require deep vertical cutting of the hill slopes rendering it prone to frequent landslides. Further, because of the 12-metre road formation width option being followed, the space crunch between the hill face and the valley slope compelled the builders to abandon the normal practice of using the huge quantity of muck excavated from the sides of the hills to make filled sections between retaining wall and the valley-side of the road. The excess muck now ends up as material dumped over the valleys eventually adding onto the bedload of rivers negatively affecting their flow dynamics. Thus, what the road building engineers would call a ‘cut-and-fill’ procedure has been reduced to ‘cut-and-dump’. The exponential increase in the incidences of landslides in Uttarakhand and the tunnel collapses along the Char Dham route needs to be assessed in the background of the unscientific construction practices followed by the contractors.
The literature on the collapse of a tunnel is a rather complex problem because it is strongly influenced by the random variability of the mechanical properties of the rock in situ and the presence of cracks and fractures in the rock formations. When these disasters happen, government representatives have a tendency to call them “geological surprises”. If you do such massive infrastructural projects in a tectonically dynamic and environmentally fragile landscape like that of the Himalayas with limited expertise, anything would be a “surprise”. The same part of the Yamunotri tunnel is reported to have collapsed in 2019, but the scale of the cave-in was less severe and no workers got trapped. Previously such excavations in the mountains were carried out under the constant supervision of competent geologists, followed by recording rock mass properties and continuous tunnel logging among other precautionary measures.
Safety during tunnelling and service periods should be the main concern in tunnel engineering. Apparently, no such Standard Operating Procedures have been followed here. The question is why no safety norms or reviewing had been ordered by the authorities even after a tunnel collapse from the same area happened in 2019. What were the supporting measures taken in the previously collapsed area and how intensely this vulnerable patch has been monitored to collect the deformation data? When tunnelling begins, the stress of the surrounding rock is readjusted and redistributed, worsening the stability parameters and causing the displacement of the surrounding rock, leading to the tunnel collapsing.
The continuous rain could lead the surface water to seep and soften the surrounding rock, lowering the cohesiveness, and thus weakening the surrounding rock, causing collapse. It is important to identify such weak areas beforehand and the presence of an onsite geologist who understands the competency and nature of the rock formation would have been beneficial in identifying the vulnerable patches. Based on the competent advice, steps should have been taken to provide primary support including scaffolding and steel rods to reinforce the vulnerable portion. It is not clear whether such measures have been taken after the initial collapse was reported from the Yamunotri tunnel in 2019. The modern tunnel guidelines prescribe escape routes at an admissible distance for emergency exits leading to a safe zone, which can be an escape shaft – an exit to the open air. Have the builders or the contractors followed such minimum safety requirements during the construction process of the Yamunotri tunnel? Do we have any national guidelines for the tunnel construction in the mountainous environments? I think the Union and the state governments should answer these questions.
The tunnel construction failure on the Brahmakhal-Yamunotri road in Uttarkashi district is the most recent one in the trail of disasters we have witnessed in the Himalayas since the road construction was started. Despite the objections raised by the expert panels, and the caveats issued by the courts, the government has been able to steamroll the work with no intention of reviewing the emerging scenario. The government in its politically motivated enthusiasm to complete the project in a short time turns a blind eye to this clumsiness that has seriously impacted the mountain environment that is already reeling under the global warming trends. Otherwise, how do you explain a situation where about 40 people trapped under the rubble were working in the early morning on a Diwali day? The work was going on 24X7 and the contractor must be under tremendous pressure to complete the work bound by some deadline given by the authorities.
The currently reported tunnel collapse is yet another example of the ongoing chain of human-engineered disasters in the Himalayas related to the Char Dham project that violates all environmental norms and standard operating procedures. When the Char Dham case was heard in the Supreme Court, the government pleaded that with the construction of this road, it would be easier for the Indian Army to reach the border with tanks and weapons and would increase connectivity in the mountainous areas. Although the Yamunotri stretch of the road is exempted from widening, which follows the plan of an intermediate width of 5.5 metres of tarred surface, the Supreme Court had approved the widening of other parts of the Char Dham, saying the court, 'can't second-guess the infrastructural needs of the armed forces'. It remains unclear how a disaster-prone road network can ease the army movement to the border areas or the pilgrims’ progress.
In light of this disaster and other such incidents elsewhere, including the one that happened in the Joshimath area, the government should immediately stop the entire road construction activities related to the Char Dham scheme as well as the tunnelling work along various parts of its stretch until a thorough scientific review of this project by independent experts is conducted.
Leave a comment