Tunnelling activity in India has accelerated in recent years due to several growth factors. Increasing government support, adoption of cutting-edge technologies and processes, increased investments, and initiatives to improve rural connectivity are a few of them. In a panel discussion at “Infrabuild India”, government and industry stakeholders discussed the experience so far in tunnel construction, tunnelling techniques, implementation of key tunnel projects, impact of Covid-19, issues and challenges faced, and upcoming opportunities. Excerpts…
Sanjay Dave
HCC India has developed 364 km of tunnels, including 204 km in the rugged Himalayan region. In a major development, the company has successfully completed the Kishanganga hydroelectric project with 14 km of tunnel boring machine (TBM) tunnelling and a record 816 metres in a month, after facing all the challenges and moving past all the difficulties.
HCC has a mix of engineering, procurement and construction contracts as well as item-rate contracts. The type of contract depends on time availability and the detailed project report (DPR) of the project. Given the unpredictability of environmental and geotechnical circumstances in the Himalayas, geological surprise is one the biggest challenges faced in tunnel construction in the region. There are challenges in TBM operations in the Tapovan Vishnugad and Vishnugad Pipalkoti project.
Tunnel construction for metros is a complex job because of the congested environment. A complete DPR is created by the client/owner, including a geological base line report. However, there may be differences between the report and reality, resulting in changes in rock class and support systems, and extended time, claims, arbitration etc.
Covid-19 had a significant influence on the sector, since guidelines were constantly changing. After the lockdown was lifted, the government provided no facility for workers to return to the construction site the way they enabled workers to reach their homes. Further, maintaining social distance while working was a tremendous challenge. Apart from this, wearing a personal protective equipment kit on sites lowers the productivity of workers.
The outbreak of the ongoing pandemic has brought attention to the potential and benefits of digital interventions. These include hands-free sanitisation for workers, use of various technologies such as facial recognition and iris technology for attendance marking in place of touch-based biometric systems and use of drones to monitor the project’s progress at various sites. In assessing a work at project sites, artificial intelligence and PTZ cameras play a critical role. Data transfer and analysis have also been simplified. Geological conditions up to 100 metres are being assessed using tunnel seismic prediction (TSP) methods. Two- and three-dimensional design tools are being used. Further, three-dimensional project simulation models are being used to train project engineers and labourers without compromising the safety of workers. Digitalisation has resulted in an indirect increase in efficiency. Diesel-powered machinery makes it more difficult for workers to breathe, which has made ventilation essential. Various technological advancements have been implemented, including the use of gas detectors for tunnel development and the use of vacuum and forced ventilation for all significant projects.
Future outlook
Tunnels are being actively constructed in difficult terrain to ensure that a strong ecosystem is established for swift implementation of tunnelling activities in the country. The tunnelling industry has witnessed a steady increase in demand from the infrastructure sector over the past few years owing to the growing needs of diverse sectors such as railways, metro systems, roads, hydropower, water supply and sewerage. Going forward, roads and railways in the North and Northeast have a huge number of tunnelling opportunities coming up. There are also opportunities in the hydropower segment.
M.M. Madan
By 2030, India has announced a target to achieve 75 GW of installed capacity of hydroelectric power projects, which will be accomplished by 26,000 MW of new hydroelectric projects. Currently, over 9,000 MW of hydropower projects are under construction in Jammu & Kashmir, Himachal Pradesh, Uttarakhand, Arunachal Pradesh, Sikkim, West Bengal and Andhra Pradesh. Many prestigious hydropower projects had been taken over by private developers, but the progress of these projects was slow. Recently, the prime minister announced the re-allotment of hydro projects that had previously been alloted to the private sector in Arunachal Pradesh to PSUs such as NHPC, SJVN, NEEPCO, THDC, as well as the allotment of new projects to various states like Uttarakhand and Himachal Pradesh. Due to the availability of superior construction equipment and materials, modern technology, and application of better planning and execution strategies, tunnelling activity in India has improved significantly in recent years. Previously, the Indian government did not focus much on hydropower development. However, it has been recognised that the country will be unable to progress without hydropower.
Currently, due to a sudden increase in execution of infrastructure projects in roads and highways, railways, metro, water supply and hydropower projects, there is a shortage of trained workers and experienced construction engineers, design engineers and contractors, among other issues. New contractors from infrastructure sector are shifting to the hydro sector, but they lack expertise and training. Through agreements with JVs, they will gain hydro expertise. As the hydro projects are located in unapproachable, high mountains, 100 per cent investigation of the geological technical parameters for project construction cannot be done, therefore preparing as accurate a GBR and risk sharing matrix as possible is the most important part of any contract. The risk sharing shall be pre-decided and a part of the contract. The sad part is that developers are keeping a ceiling on risk sharing, which troubles contractors because it defeats the whole purpose for which it has been introduced in modern contract practices. This results in suffering for both contractors and owners and delays project execution. Due to Covid-induced restrictions on conducting workshops physically, engineers are being trained at a minimal cost via web workshops and webinars to understand how to plan and analyse the complexities of design. This will help enhance the design capacity of engineers.
The safety of workers on tunnelling projects is one of the areas that require utmost attention. To this end, safety equipment has been made mandatory and penalty fees are imposed in case of any violation, whether by engineers or contractors. After the construction of tunnels, a digital monitoring system should be installed to monitor safety throughout the life of the tunnel. In case of any deformation after the construction of the tunnel, an alarm will go off, which will immediately give an alert to the owner of the project at their office or HQ. Going forward, the hydropower, roadways, railways and metro sectors will offer maximum opportunities in the tunnelling segment because of fast-track infrastructure development being carried out in India.
Colonel Parikshit Mehra
At a height of 10,000 feet, the Atal Tunnel is the world’s longest roadway tunnel. It has instilled trust in tunnelling in any type of geology in the country. In the Ladakh region, several tunnelling projects have been planned. For river line projects, DPRs are being created. Initially, there was aversion towards the deployment of TBMs. However now, technological advancements in TBMs have made them more adaptable to varied geology.
Construction activities on tunnels at high altitudes face challenges pertaining to excavation and ventilation. The most challenging task is to keep working on the excavation during the winter season when there is a lot of snow. Other challenges faced during project execution include assembling workers in such poor weather conditions and improper risk allocation. The risk should be divided between the owners and the contractors, forming a proper risk sharing matrix to safeguard the profits and interests of all stakeholders.
The Covid situation demands special measures. Teams should work in Bio Bubbles so that spread can be localised and minimised. Health and safety measures especially proper ventilation are the need of the hour to attract better manpower and reduce time required on excavation. This will aid in reducing project times and improving their economy. The crux of the FIDIC Emerald books is likely to find its way in Indian contracts within the next couple years.