There has been a surge in tunnelling activity in the country, as a large number of infrastructure projects are being implemented across sectors such as railways, roads and highways, water supply and sewerage, and urban mass transit. Over the past few years, the tunnel segment has received greater attention due to increased congestion in urban areas, which has left little scope for on-ground construction. As a result, newly evolving tunnelling techniques offer greater flexibility to contractors. These mechanised techniques are gradually replacing traditional or non-mechanised methods of tunnel construction. While they usually involve higher equipment and transportation costs than conventional tunnelling techniques, they ensure timely project completion and faster returns on investment.
Increasing investments in tunnel construction have resulted in high growth of the tunnel equipment market as well. Going ahead, as the pressure on land increases (with land being required for other productive, economic and social uses), the demand for underground structures will rise, as will the demand for more sophisticated equipment. The increased demand for high-tech equipment is being driven by geological complexities that pose a huge challenge to tunnelling projects. Meanwhile, navigation systems, computerised jumbos and advanced drilling systems are being deployed for precision and better monitoring.
Emerging equipment requirements
Equipment for tunnel construction is acquired either through purchase of new machinery, purchase of used/refurbished equipment, or renting of equipment. Choosing from among these options depends upon the availability of funds, the number of work hours required, and the proposed timeline and work schedule.
Drill-and-blast is the most commonly used method for tunnelling in India. Some of the key types of equipment used in this method are double boom jumbo machines (underground drilling machines), road headers (rock-cutting machines for excavating tunnels) and drilling rigs (used to dig holes in the subsurface). Tunnel contractors usually prefer to purchase these machines. The key suppliers in the segment include Alstom India, Atlas Copco, Texmaco Rail, Terratec and Robbins. Equipment suppliers also provide other services such as inspecting equipment on demand, providing skilled manpower for installation, and maintaining inventory of spare parts. An annual maintenance contract is also offered, under which the payment is made on a per metre basis and the entire risk is borne by the equipment provider.
The tunnel boring machine (TBM) method has also witnessed significant adoption, especially in the development of metro tunnels in congested urban areas. It has also gained prominence in the water supply and sewerage sectors. TBMs can be broadly classified into four types – soft ground, slurry, hard rock and hybrid TBMs.
Tunnel contractors primarily import TBMs that are designed and manufactured by foreign suppliers. China continues to dominate the tunnelling equipment market, followed by Finland and Germany. The major TBM equipment suppliers include Herrenknecht, Caterpillar, Hitachi Zosen, Akkerman and Robbins. In the past couple of years, TBM equipment suppliers have also started offering services such as complete logistics support, on-site first-time assembly, technical assistance, specialised manpower for maintenance of machinery, and on-site excavation services, as per client requests.
More recently, the New Austrian Tunnelling Method (NATM) has also gained traction. Significant tunnel length in the railway and road sectors is being developed using NATM. Apart from excavators, loaders and tippers, the two main types of equipment used in NATM are boomers and shotcrete machines with robotic arms.
Over the past few years, there has been an increase in the demand for technologically advanced tunnelling equipment due to projects being undertaken in areas with geographical complexities. Advanced drilling systems, computerised jumbos and navigation systems are increasingly being used for greater precision and better monitoring. The navigation systems deployed in TBMs help in providing a continuous reference point for the machine’s position. Under these navigation systems, a beam is picked up by the targets at the back of the TBM. Further, use of strength monitoring using thermal imaging technology helps in assessing the strength of the whole shotcrete lining in real time from a secure position, bringing huge benefits in terms of safety, quality control and productivity.
The road ahead
Going forward, the adoption of international standards in tunnel design and construction is expected to increase. However, there is also a need to reduce dependence on other countries for advanced tunnelling machinery. The key countries exporting tunnelling machinery to India are China, Finland and Germany. India needs to move away from such imports towards greater self-reliance, and encourage domestic production. Other issues that must be addressed to facilitate growth of the tunnel equipment market in India include shortage of skilled manpower for operating and maintaining TBMs, absence of spare parts inventory, geological surprises, and inadequate investigations resulting in a high wear and tear of equipment.