Located in the state of Uttarakhand, the Rishikesh to Karnaprayag Railway will provide a broad-gauge line that is Indian Railways’ chosen route for the Char Dham Railway. It will connect to the Chota Char Dham, being one of the major initiatives of the Indian government to improve transport and communication in the area.
The rail link has been designed to connect the Hindu pilgrimage towns of Devprayag, Srinagar, Rudraprayag, Gauchar Karnprayag with five districts of Dehradun, Tehri Garhwal, Pauri, Rudrapryag and Chamoli.
This 125km route starts at the newly-built Rishikesh railway station which is located 380m ASL, and terminates at Karnaprayag, 825m ASL. With a total of 12 stations and 35 bridges along the route, the longest being 460m long, the project will also feature 105km of line (85% of the total length) inside tunnels.
Comprising a main tunnel with a parallel rescue tunnel and ballast-less track, the 15.1km Devprayag-Lachmoli tunnel will, when completed, become India’s longest and a key component of the project (the current longest is the 11.2km tunnel from Banihal to Quazikund linking Jammu to the Kashmir valley). Due mainly to unpredictable geological conditions, the new line will be broad-gauge and is considered to be one of the most prestigious infrastructure projects undertaken by the Indian government in recent years. It will not just improve the connectivity to Char Dham (the ‘pilgrims of India’) but also help thousands of people who travel from the hills to the plains on a regular basis.
The line is expected to be operational by 2024/25 when journey times between Rishikesh and Karnaprayag will be slashed from over seven hours to just over two.
The design consultancy contracts for tunnel and bridge construction were awarded in 2018-19. Italferr, the engineering arm of FS Italiane Group – as part of a joint venture with Lombardi – was awarded the contract for the executive design and works supervision of the first 12km section (running almost entirely through tunnels). Work on the line began in 2019 and will be excavated by APCO Infratech, the fastest growing mid-size infrastructure company in India.
Costs for the project have increased to an estimated US$2.3bn as, besides inflation, the cost escalation is due to the inclusion of the separate rescue tunnel. This was undertaken following guidelines issued by Indian Railways.
Tough Geology
The railway will run parallel to the river Ganges in the Himalayas. Due to the ‘young’ nature of rock being encountered, tunnelling is facing many challenges. This includes gauging the geological conditions and, in particular, the rock hardness in order to better assess the required drilling and blasting patterns. The rock encountered has mainly been a purple sandstone / quartz arenite. This is composed of greater than 90% detrital quartz, with limited amounts of other framework grains (feldspar, lithic fragments, etc.) and matrix. It can have higher than average amounts of resistant grains, such as chert and minerals in the ZTR index. Also, operator safety is considered to be paramount, while the project’s tight deadlines require the use of automated equipment to provide higher levels of productivity.
Automation is considered essential, as high-performance drill and blast requires that each of the individual working elements that constitute the construction process are optimised, comprising a system of sequential and parallel activities. In order to achieve the increased production required on the project, equipment manufacturers and providers of blasting services are increasingly looking at ways to improve their processes. This has seen promising developments being used that take drill and blast to new levels of productivity, delivering highly effective solutions with increasing levels of ‘intelligence’ and automation.
First DT922I in India
In recent years, some of the most interesting developments in drill and blast have occurred in tunnelling jumbos and underground drill rigs. Increasingly automated and highly fuel efficient, they can also provide environmentally friendly performance. These machines have become indispensable for use in drilling and blasting, with their flexibility and relative compact size being of huge benefit. As a result, they have become increasingly popular in tunnelling projects globally, especially where rock hardness/geological composition and other factors prevent the effective use of TBMs (as in the case encountered on tunnel excavations on the Rishikesh to Karnaprayag line in general, and the Devprayag and Lachmoli tunnel in particular).
Proving a key tool in excavating the Rishikesh-Karnaprayag line is the first DT922i tunnelling jumbo Sandvik has supplied to India. Acquired by contractor APCO Infratech, the jumbo marks what is regarded as the beginning of computer controlled tunnelling in India. Fully automatic and armed with Sandvik’s intelligent iSure and iSure Geo patented software for underground rock excavation, it is expected to make work on the tunnel safer and more productive.
As with all Sandvik ‘I’ Series rigs, the DT922i effectively provides automated multipurpose face drilling. It has the capability to drill one complete round accurately with a high level of repeatability, according to a pre-designed drill plan, with minimal intervention from the operator. The iSure system for data collection analysis and process control is said to improve the work cycle and the process, assisting geological interpretation and so bringing considerable savings to drill and blast. Furthermore, it also generates critical reports on drilling operations, efficiency and use of the DT922i rig, as well as providing drilling parameters in order to assess blasting vibration and pull-out analysis.
Traditional excavation solutions have meant that tunnel profiles are not always straight due to operator errors, with holes not being accurately placed and/or not at the desired angle. This often results in overbreak or underbreak which is very expensive and requires the driller to take remedial action, as well as providing further – and expensive – roof support. Correcting these issues slows the rate of tunnelling, results in project delays and often, cost overruns. The real benefit in using the DT922i on the Devprayag- Lachmoli tunnel is that, as a fully automated solution, it eliminates potentially poor operator decisions. This means that unlike a conventional hydraulic drill rig where the tunnel profile is always based on the operator’s judgement regarding where to drill, at what angle and at what depth, the automation provides more accurate and productive drilling.
Underground Rock Excavation Software and Rock Analysis
APCO Infratech’s DT922i has helped ensure that the drill and blast process is optimised as its template-based drill-plan generation tool takes into account rock blastability, tunnel profile quality target and explosives used. This has resulted in effective, controlled blasts resulting in good pull-out, a restricted fracture zone and greater rock strength around the tunnel. Furthermore, it has allowed blasting-round length and detonation to conform to the permissible vibration levels and geology. iSure, as seen in India, helps to achieve this, as it provides a set of plan templates for editing and feedback functions to achieve the best possible result from the blast, with blast patterns being easily edited to match the design parameter.
The DT922i is equipped with iSure Geo – a rig-integrated, high precision, online rock-mass analysis and visualisation system for tunnel process optimisation. This provides rock mass information and a view inside the drilled rock, thereby improving the overall tunnelling process in terms of efficiency and quality.
Geological information provided by the onboard rock-mass analysis and visualisation system has proved vital while tunnelling through the Himalayas. Designed to be used with Sandvik underground construction drills rigs, iSure Geo delivers onboard analysis of the rock mass which can provide numerous benefits to tunnel excavation. Not only is it an easy way to fulfill any advanced reporting requirements, it also acts as an important tool for the assessment of rock reinforcement or injection requirements.
It also serves as an assisting tool for charging and blasting control, as well as a complementary tool for geological mapping.
As all information is provided, the technology enables the drill rig to act as an analytical tool. There has been no need for any third-party devices, add-on sensors or separate data transfers, as the analysis is fully integrated into the drill rig. This has further meant that iSure Geo can provide accurate and repeatable results, however this also requires that operatives understand how to use its capabilities. To this end, Sandvik technicians trained the drill-rig operatives following the installation of a Digital Driller simulator training facility at the RVNL campus in Rishikesh.
Designed To Be Tough
The DT922i is designed to operate in the toughest of Indian environments. Its small number of hydraulic hoses minimise oil spillages and aid environmental protection (a key concern on the Rishikesh–Karnaprayag railway) which in turn substantially cuts down on the frequency of maintenance downtime.
As the jumbo is required to work continuously in some of the harshest conditions, due care has been taken to ensure operator safety and comfort. The DT922i is equipped with a soundproofed, next generation iCab operator cabin which conforms to ROPS (roll-over protection system) and FOPS (fall-over protection system) certification.
In order to improve drill and blast performance, Sandvik Alpha rods and bits have been used throughout, resulting in higher penetration rates and greater tool life (thought to have increased by around 20%).
The first jumbo has completed its work at Adit 2 ahead of schedule, with the simulator enabling operators to undergo training in a safe environment. In addition, Sandvik is also providing round-the-clock support, regular servicing and maintenance, as well as supplying parts and rock tools from a local inventory when required.