An industry manager explains the most important elements of the CANI submarine cable system, the laying process and the hardships that were withstood from start to finish.
Between the coast of Chennai and the beaches of the Andaman and Nicobar archipelagos, there is a 2,300-kilometer network of submarine fiber optic cables. The Chennai-Andaman & Nicobar Islands System, CANI for short, is the only undersea cable that serves Indian territory alone – a similar system is being planned for the Lakshadweep Islands. Systems like CANI – on a larger, intercontinental level – make the global nature of the Internet possible and offer several terabits per second of broadband capacity between countries.
From November 2019 to August 2020, Bharat Sanchar Nigam Limited, the state-owned telecommunications operator, laid most of the cable system on the floor of the Bay of Bengal, spanning the great distance between the capital Tamil Nadu and the islands (port cities in Thailand and Myanmar are the Andaman Islands and Nicobar Islands much closer than Chennai).
The fiber optic cables were manufactured by NEC, a Japanese telecommunications company. Ashutosh Zutshi, Vice President of Submarine Network Solutions at the Indian subsidiary of NEC, gave a webinar on August 11th about the details of the construction of CANI, how such systems are built and what challenges they face , and how they work. The webinar was organized from the National Telecommunication Institute for Policy Research, Innovation & Training.
The three elements of an underwater cable system
“The entire submarine cable network can be divided into three categories: The first is that wet plant. The second is the so-called dry plant. And the third is that Naval operations“, Said Zutshi.
“The wet plant goes into the water” – the elements of the cable system that “go into the seas and oceans,” explained Zutshi. “That’s the [optic fibre] Cables themselves, the repeaters required to maintain the power level [consistent], and the branching units, which branch the cables to different countries if required. “
And then there are common boxes. “Joint boxes connect different types of cable systems and different sections of a cable system because it is not possible to construct thousands of kilometers of cable at once,” said Zutshi. The cables are armored and insulated over a large area, with systems being harder at greater depths. The “dry system” on land connects the cable network with terrestrial networks and feeds the cables (and the repeaters, which are placed under water at regular intervals) with electricity. Submarine cables ideally end up on beaches where a large amount of sand can be dug up and quickly replaced to protect the cable. On land, the place where the cables end is named Landing stations.
- Naval operations: Before the cable is actually laid, engineers have to plan ahead and find out what the bedrock will look like – what the ocean floor will look like. “Naval operations are all about laying the cables in the sea, maintaining them and repairing them,” said Zutshi. “There are some important components [in this phase]; the first of these is the Marine Route Survey. Before we start laying the cable, we need to do a survey of the seabed to understand the contours of the seabed and plan the cable route accordingly. The planning is called marine technology; this decides how the cable must be laid and laid in order to ensure the long-term safety of the cable. Because once the cable is laid, it has to stay there for a few decades, at least 20 to 25 years, ”said Zutshi. Marine ops also step in when a submarine cable fault needs to be repaired; It does this by fishing the cable up to sea level, closing the bug and throwing the cable back into the seabed.
- Land cable suffers more damage: “Ironically, it is the land cable that suffers more damage than the submarine cable,” reveals Zutshi. While cable cuts are known to occur underwater, they are far more common on land, as the cables are closer to the ground and activities such as construction and excavation can damage the cables, which is virtually nothing to fear on the ocean floor.
List of activities when laying a CANI-like system
Zutshi outlined several activities that go into building submarine cable systems from start to finish. These are:
- Desktop study and coordination before the survey: This step involves designing a pre-survey cable route that gives a rough idea of what the route will look like before the ship’s engineers figure out the details. Coordination before the survey, Zutshi said, means “you need to examine all landing sites to see if the sites are suitable and what kind of insulation is needed”. [for the cable] and how the survey should be carried out. “
- Measurement of the sea route and coordination after the measurement: In this step, the seabed is examined and the particularities of the route are mapped. And then there are permits. “In principle, many permits are required for the construction of a cable landing station and the submarine system, depending on the country,” said Zutshi. In India, he said, survey permits should be obtained for the crew and the ship, with permits from the Ministry of Defense and the Interior. “There are higher mountains under the sea than over the land. In some places along the seabed there are very steep areas, so special care must be taken when laying the cables. It’s a very exciting and interesting world under the sea, ”said Zutshi.
- System assembly and loading: Equipped with information from the route survey, heavy equipment – and hundreds of kilometers of cable – is loaded onto the ship that is laying the cables. One end of the cable is tied to land and the line reels out and falls to the seabed as the ship moves offshore to the other landing station. “Regardless of the length of the cable, be it a few hundred or a few thousand kilometers, the entire length is manufactured in one operation – submarine cables are not manufactured in individual parts. It is a continuous cable that is loaded into the ship, ”said Zutshi. However, the cable is always cut open when a repeater has to be inserted to amplify the fiber optic signal.
- Presentation grapnel run: Before the cable is laid, the ship sweeps debris from the seabed, literally clearing the way for the cable to be laid. “This is done to remove debris or other hazardous materials from the ocean floor to prevent damage to cables. It is mainly carried out along the route where the cable must be buried. So if the funeral takes place in a place where there is a lot of rubble, the funeral equipment will be damaged and the cable itself can be damaged, ”said Zutshi.
- Cable landing, laying and laying: After the cable has been laid, the route and the line are inspected and the shaft on the beach, where the cable comes into contact with the land, is buried in the sand. A gigantic “plowing machine” cuts the seabed as the ship moves to secure the cable so that it not only rests on the seabed but is buried in it – this does not happen if the seabed is made up of corals or rocks. “As soon as the cable is laid, the end-to-end system is tested, which is known as segment test and integration. This is followed by the final commissioning and acceptance test for the entire system, followed by the necessary maintenance training for the resources, ”said Zutshi.
Challenges in laying subsea networks
Submarine networks cannot always be built, and their location can be a headache.
- When can they be built? “Of course, it is important to do marine activities when the weather is good. So the monsoon season is a no-go. You cannot do any activities during the monsoons. Whether measuring or cabling, everything has to be carried out in good weather conditions, i.e. after the monsoon, ”said Zutshi. For CANI, this meant a four-month window between January 2020 and April 2020.
- Transport: In the Andaman and Nicobar Islands themselves, transportation and accommodation for engineers working on the project were scarce. “We had to rent helicopters at many locations,” said Zutshi, adding that NEC engineers had to apply for accommodation in state guest houses due to a lack of hotels.
- Landing stations had to be built from scratch: The buildings for the network equipment and the landing stations had to be rebuilt at every landing site (except for Port Blair). That delayed things, but Zutshi said things were speeded up in a somewhat unusual way: “We did something that is normally not done in any project. We put very expensive equipment in one of the rooms when the building was still under construction. We did that in the interests of completing it on time. “
- Fischer protests: “There have been some procurement-related issues that fishermen protested in some places, particularly in Chennai. There were some environmental issues raised by these people; fortunately we overcame that with the support of the BSNL, ”said Zutshi. These protests have not yet been reported.
- Airlifting Japanese engineers: When the lockdown struck, Japanese engineers working with NEC were stranded in the Andaman and Nicobar Islands. “They [the local administration] arranged permission to evacuate them directly from the island. Otherwise, they would have had to go back to Chennai to return. So they arranged the immigration clearance on the islands themselves and they could return, ”said Zutshi. That may have been a significant relief considering how much a trip back to Chennai – over 2,000 kilometers from Port Blair – could add to travel time in the East Asian country.
- Beach erosion and repairs: While this is not a problem that CANI has necessarily faced, beach erosion is a growing phenomenon around the world due to the rise in sea levels caused by climate change. It can essentially expose shafts that are laboriously covered by a lot of sand by simply eroding the coast. SEA-ME-WE, a cable system that lands in Chennai, had a beach manhole slide into the seasaid Zutshi. While the cable that ended up in that duct was not damaged, such issues can disrupt connectivity, he warned. “Fortunately for CANI, the entrance to the beach is right on the roadside [bordering the beach]. So there is enough distance from the beach entrance to the sea, ”he added. There are also activities like fishing, anchor throwing, and more that can result in cable damage. It is time consuming and requires approval to get a ship out to fix such errors.
Quotations have been edited slightly for the sake of clarity.
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