Louis Berger: Tunnelling Through Challenges

Kshitish Nadgauda, Senior VP & MD – Asia, Louis Berger
Kshitish Nadgauda, Senior VP & MD – Asia, Louis Berger, shares information on the challenges encountered during tunnelling in the mountainous terrains of J&K and in the busy streets of Mumbai.

Louis Berger has completed many challenging tunnel projects across the world; please share your experience in one of India’s strategically important tunnel projects.
In 2004, the National Highway Authority of India (NHAI) selected Louis Berger in a joint venture with LRP Consultants to prepare the feasibility study, detailed project report (DPR) and engineering designs for the four-laning of the Udhampur to Banihal section of National Highway 1A, now part of National Highway 44. The project would eventually include replacing the existing 41-km (25.5-mile) long mountain road stretch with the 9-km long (5.6-mile) Chenani-Nashri tunnel, which would become India’s longest roadway tunnel.

Chenani Nashri tunnel

The design and construction of the Chenani-Nashri tunnel was a challenge not only due to inclement weather conditions but also due to the sheer size and magnitude of the project, and the prevailing soil and rock conditions in the area. Additionally, preservation of the endangered chinar (maple) tree forest was a mandatory requirement.

Srinagar was connected to Jammu and the rest of India by the old National Highway 1A, a narrow two-lane highway passing through treacherous terrain and some of the steepest landscapes in the world. Widening and realignment of the highway, including with new all-weather tunnels through steep rock beds, was needed to improve safety, decrease travel time and minimize roadway closures during adverse weather conditions.

The 9km-long tunnel reduces the travel distance between Jammu and Srinagar, the state’s two largest cities, by 30 km (18.6 miles), cuts travel time by about two hours, and is anticipated to boost tourism and economic growth in the region. The highway realignment will also help preserve forests in the ecologically sensitive Patni Top area of the state.

Louis Berger overcame all the challenges by working closely and collaboratively with our client, the NHAI, the consultant, contractor and other stakeholders, and ensured successful delivery of the project, minimizing or avoiding delays, and within the original budget. Today, the Chenani-Nashri tunnel is widely acclaimed as India’s longest and safest roadway tunnel in the heart of the Himalayas.

What steps were taken to overcome the challenges while building the Chenani-Nashri tunnel?
The old National Highway 1A was a narrow two-lane highway passing through challenging and rugged terrain, with steep gradients. Widening and realignment of the highway, including new all-weather tunnels through steep rock beds, were needed to improve safety, decrease travel time and minimize closings during adverse weather conditions.

The two major challenges were the terrain and the type of rock in the mountains all the way from Udhampur to Banihal. Our team assessed the environmental and social impact of the project, including cultural properties, natural habitats and involuntary resettlement. In fact, during the design phase, since the team had to go through every parcel of land with precision, the expert teams had to walk multiple times along the 122km length over a period of 4 days to verify the compatibility of the design with the site conditions!

The team overcame these challenges by designing the alignment with great precision, with several iterations to ensure accuracy. We also had to ensure during the design phase that the hill cutting was optimized, and minimize the overall ecological impact, without disturbing the forests of rare Chinar (maple) trees.

Another challenge was the large number of monkeys along the stretch. So, we incorporated in the DPR monkey-crossing structures at required locations - this is unique to the Chenani Nashri project!

The design of bridges and viaducts was also challenging due to the necessity of tall piers on account of the mountainous terrain and the high-risk seismic zone. Due to the nature of the rock, it was essential to stabilize cut slopes to avoid landslides. Our geotechnical experts studied the type and nature of the rock along the 122km alignment to design unique slope stabilization measures. Wherever feasible, tunnel options were explored, and accordingly, small tunnels at 8 locations were designed.

What are the important considerations during the development phase of tunnel projects?
Foremost amongst the challenges encountered is the selection of the site and optimum (shortest) alignment with horizontal and vertical geometry befitting the importance and category of the project, and other design criteria. Establishing the location of tunnel portals can also be a challenging task. The design must also allow for smooth connectivity of approaches to the tunnel.

Perhaps the most challenging task is the assessment of site geology, collection of geological maps, and establishing and executing an adequate geotechnical investigation program to inform the design of the tunnel and to ensure that the design is optimum. Ground movement, ground deformation and building settlements have to be minimized. It is, therefore, also important to assess and establish the construction methodology and fronts for construction such that safety is ensured at all times, along with minimum cost and duration.
Today, India is probably the fastest growing market for tunnel construction. International construction techniques such as New Austrian Tunnelling method are being implemented, TBMs are being used, and international norms and fire safety codes along with evacuation preparedness are being followed.

For engineers, tunnelling in hilly areas means dealing with difficult terrain conditions, in-situ stresses, ingress of water and gases, geothermal gradient, high-level of seismicity, etc. What technical know-how does Louis Berger provide for such projects?
For the DPR of the Chenani-Nashri tunnel project, Louis Berger conducted the design of all proposed tunnels in accordance with the New Austrian Tunneling Method (NATM). The design included civil works, electro-mechanical works (ventilation) and lighting, as well as state-of-the-art Control Centres.

Geological investigation plays a vital role during the design and construction stages to decide a suitable construction method and support arrangement. The advanced investigation tests are been carried out according to terrain conditions such as electromagnetic geophysical surveys, hydraulic fracture test, flat jack test, stress relief techniques, strain recovery methods, borehole breakout method along with fault slip data analysis for measurement of residual stresses etc.

A laboratory is set up at site for routine investigations to compare the design assumptions and construction approach. Further fore-poling is carried out and cores are collected before excavation cycle to ensure expected geological scenarios and avoid unforeseen surprises.

How do you rate India in terms of its technology and expertise in tunnel construction?
Today, India is probably the fastest growing market for tunnel construction due to the large number of roadways, rail and metro rail projects that are being implemented on a phenomenal scale as never before. In addition, large water supply, sewerage and storm water drainage tunnels are also being constructed. As a result, there is a large number of international consultants and contractors specialized in tunnels, present in India.

International construction techniques such as NATM (New Austrian Tunnelling method) are being implemented. TBMs (tunnel boring machines) that are manufactured and imported across the globe are also being used. International norms and NFPA codes (National Fire Protection Association) for safety and evacuation during fire are being followed.

tunnel projects

What are the current tunnel projects being undertaken by Louis Berger? Please elaborate on one of them.
Besides the Chenani-Nashri tunnel, Louis Berger recently conducted the design review of a 46km long railway tunnel between Karad and Chiplun. We are also working in the capacity of PMC on the Mumbai-Pune Expressway. The augmentation project includes 10km long twin 4-lane tunnels along a new alignment of the expressway in the ghat section. In addition, we are part of the General Consultant consortium for the 33-km long Mumbai Metro Line 3 that is presently under construction. Apart from these projects in India, we have extensive tunnel design and construction experience on projects worldwide.

All tunnel projects have their unique and distinctive features and challenges. The tunnelling work for the 33km-long fully underground Mumbai Metro Line 3 project is no exception. This line extends from Cuffe Parade in South Mumbai to the Aarey Milk Colony in the western suburbs to the north. The underground alignment passes under a diverse set of developments including high-rise buildings, heritage structures, delegate buildings, residential and commercial developments including hutments and the Mithi River. The project includes 26 underground stations and one at-grade station.

The assessment of the geology and geotechnical profile of the underlying strata along the alignment was a significant challenge, since Mumbai comprises seven islands. The varying strata includes hard rock, shale, as well as backfilled soil. The tunnel boring machines were therefore designed to suit the ground conditions.

The survey of existing buildings that was conducted was also crucial to categorize the condition of buildings as good, moderate or severe. This was important to ensure the stability and integrity of structures during tunnel construction. Protection of heritage buildings is also of utmost importance. Instrumentation to measure ground deformation and vibrations was placed in this regard. In addition, mapping of existing utilities and then relocating them if impacted by the alignment also needs to be done carefully.

NBM&CW March 2020

Grundfos Sustainable Solutions for India’s Water Woes

Saravanan Panneer Selvam, General Manager, Grundfos India, emphasises the need for energy-efficient products and solutions to address India’s water problems and believes that automation can help streamline the water processes Read More ...

AJAX: Next-Gen Technological Player in Indigenous Concreting Solutions

AJAX, a leading concreting solutions company, has been providing a wide range of equipment to Indian and global customers for over 28 years. It is the only Indian company to design, engineer, and manufacture next-gen solutions Read More ...

BKT: In Expansion Mode

Unfazed by the Covid-19 crisis, OTR manufacturing behemoth Balkrishna Industries Limited (BKT) is continuing to work on its long-term business plans. Even while sales of OTRs in India and in global markets remain bearish Read More ...

G R Infra On the Road to Success

Vinod Kumar Agarwal, MD, GR Infra, discusses the factors that led to successful execution of two of their most prestigious projects, particularly the machines and after-sales support provided by AMMANN India. Read More ...

JCB India

Big-ticket infrastructure development projects not only demand the best quality output but also work on tight timelines, thus creating a need for specialized, intelligent, and technologically advanced construction equipment Read More ...

KNR Construction Limited

Contractors, manufacturers, rental companies, and financial institutions have to converge to contribute meaningfully for the revival of any project through correct and timely construction processes while improving the value of Read More ...

Tata Hitachi

Just before Covid-19 started, we had ventured into the rental business of machines, and today, these machines have been productively deployed at sites. The trio of contractors, OEMs, and financers have been converting the Read More ...

Ardent Group

Our rental and manufacturing divisions have been playing a vital role of being the link between the contractors, financers, and institutions for the revival of our projects. Our supply chain is intact and we are producing Read More ...

Larsen & Toubro

L&T Construction Machinery has taken a significant step towards ‘Make in India’ mission. Our range of wheel loaders and vibratory compactors are fully designed, developed and manufactured in-house with over 80% localisation Read More ...

Shapoorji Pallonji E&C

We are eager and striving hard to bring our operations back on track post the lockdown. Going forward, we will focus on our ongoing projects and continue to engage with the government as well as private sector clients to explore Read More ...

Escorts Construction Equipment

Covid-19 has enhanced the role of connecting digitally the entire ecosystem of an equipment. We have already started to integrate and test a newly developed software and hardware and the results are exciting. Now, by using Read More ...

SPML Infra Limited

We believe that use of digital technologies help in higher productivity with ease of operations and maintenance. Having recognised the importance of automation and digitization, we have implemented them for quick decision Read More ...

Wirtgen Group

The Indian construction equipment industry volumes have doubled since 2015 and most manufacturers have already increased their capacities to meet the peak demand and the anticipated demand, expecting the boom to continue Read More ...

Starworth Infrastructure and Construction

Indian Construction Industry need to focus productivity at site. By doing so only cost and timeline can be optimized. The only way to enhance productivity would be to do maximum offline construction namely, precast Read More ...

Action Construction Equipment

Equipment funding is a very important aspect and the recent lockdown and subsequent moratoriums have created an array of problems for the NBFCs and the reason why the CE Industry at the current juncture is feeling a constraint Read More ...

Louis Berger

We are ready and poised to continue to work on infrastructure projects that are in the pipeline across diverse sectors including transportation and urban infrastructure – planning and design. We have competent and experienced Read More ...

New Building Material & Construction World

New Building Material & Construction World
MGS Architecture

Modern Green Structures & Architecture

Modern Green Structures & Architecture

Lifting & Specialized Transport

Lifting & Specialized Transport

Indian Infrastructure & Tenders Week

Indian Infrastructure & Tenders Week