Rabu 3hb Okt 2012 – Aku berkesempatan melawat Stesen Kabel Dasar Laut yang dikawalselia oleh Telekom Malaysia. Stesen ini terletak di Kuala Muda, Pulau Pinang. kawasan yang pernah dilanda Tsunami Acheh pada tahun 2004 dahulu. Untuk pengetahuan tuan puan pengguna internet tegar sekalian, dengan adanya stesen-stesen seperti ini beroperasi kita dapat menggunakan internet. Kabel dasar laut yang digunakan adalah jenis fiber optik.
About 99% of international telephone and Internet traffic travels through underwater cables.
WE are all accustomed to seeing roads being dug up and refilled for cable laying activities. How different is it then, when it comes to laying cables across rivers and open seas?
The fact is, digging could not be avoided as well, if such cables pass through areas that are used for ship anchoring, or are constantly trawled by fishing nets, or if the channel is about to be dredged to make it deeper for navigation.
While submarine cables appear sturdy, they are vulnerable to accidental damage from shipping and fishery activities, or natural phenomena such as strong currents or earthquakes.
Work in progress: A cable laying ship at work. The cable resting on the shore will eventually be buried to protect it from damage. Submarine cables are the unseen infrastructure that binds the modern world together. — Picture courtesy of Global Marine Systems
The submarine cable that carried Internet traffic (also known as data cables) near Taiwan broke at many points in the 2006 Taiwan earthquake, severely impacting connectivity between Asia and the United States. The major Tohoku earthquake in north-east Japan last March 11 also proved to be highly damaging to the cables located near the epicentre of the quake.
Captain Joe Hiew Heng Foo, managing director of RS&L Marine, the oldest local player in the cable installation and maintenance industry, has seen his fair share of submarine cables damaged or displaced by bottom trawl fishing nets and ship anchors.
“Sometimes the contractor did not bury the cable deep enough, so ship anchors ended up snagging them.”
Hiew had seen how dredging activities around Port Klang had damaged a telecommunications cable, even though its location was marked in navigational charts.
At times, cables are damaged due to theft.
“There was one incident in which thieves hoisted up a 10km stretch of fibre optic (data) cable in the sea, and cut it up to be sold as scrap. However, they did not realise that there is no copper or other precious metals inside the cable. Glass fibre has no value to a thief, but then the damage has been done,” said Datuk Baharum Salleh, CEO of Symphonet, an ICT business startup which is proposing to lay a new submarine cable to Vietnam and Indonesia from Malaysia.
And because cables near shallower waters are more susceptible to damage due to human activity, the task of laying cables in these waters is fraught with risk. According to Ian Douglas, managing director of the telecoms business unit of Global Marine Systems, a company runs the most risk of losing money when undertaking cable laying jobs in shallow waters and along short stretches.
“Laying fibre optic cables in deep water is actually quite low-risk. For example, if you are laying across the Pacific, you will soon get into a routine. The job may take a long time, but it is fairly low-risk,” said the engineer who has been in the business for 15 years.
“The job is a fairly simple process once the cableship starts laying at the deep water portions. You don’t have to deploy a plough (to bury the cable), there are no complex marine conditions, and no crossing of pipelines,” explained John Hibbard, a consultant in the submarine cable business, at the Submarine Networks World Conference in Singapore last year.
The rule of thumb: if the cable is laid in waters shallower than 50m, it would have to be buried to protect it. A trench should be at least 1.5m deep, though adequate protection against heavy anchors only start from burial depths of at least 5m.
“In anchorages, the cable is typically buried between 5m and 10m; we developed the 10m technology for use in Singapore and Hong Kong ports,” said Douglas.
In fact, the world record for cable burial (not a fibre optic, but a power cable) took place in Malaysia. In 2010, Global Marine Systems laid a power cable for Tenaga Nasional Bhd (TNB) to supply electricity from Port Klang to Pulau Ketam. The cable length is no more than 30km, but the logistics were mind-boggling.
“We had to create a special plough to enable us to bury the cable 14m under the sea bed, which is a world record for undersea cable burial. It was the deepest ever achieved, and that was on the edge of technology. Ships will get bigger, and the channel will have to be dredged in future. In a way, this is futureproofing against larger vessels.”
According to TNB, the project costs RM68mil – with RM42mil just for the undersea cable alone – and the utility does not think it will ever recover the cost of laying the cable from the limited number of consumers on the island.
Where burial is impractical, a cable protection zone may be enforced whereby all potentially damaging human activities are prohibited, though such measures are only as good as enforcement activities. Other than vessel patrols and monitoring of all ship movements, dialogue with other seabed users, along with public education regarding the importance of submarine cables, is also an effective protection measure.
According to Douglas, the financially high-risk jobs are the ones that are typically located in shallower waters, such as connecting an island and the mainland.
“Often, subsea conditions are rather difficult. You have to deal with currents, tides, and you have to bury quite deep. In short, there are lots of marine challenges on short systems, and when things go wrong, you have very few options to fix things in a way that would still turn in a profit. You tend to lose money on short jobs, and turn in a profit from the larger jobs,” he explained.
According to Hiew, sometimes the contractor has to take soil samples from the seabed (besides using sonar and underwater cameras to map the terrain to ensure that optimal alignment is chosen), and spot wrecks and other cables that are laid nearby.
Different types of fibre optic cable armouring to meet different levels of cable protection required. As a rule of thumb, the closer to shore, the thicker the armouring should be. The thinnest armouring is for cables laid in the deepest seas, where they are unlikely to be damaged by fishing or anchoring.
“You have to be careful so that you do not damage the cable while handling it. The industry circle is small, and word of your mishaps travels pretty fast and wide.”
Currently, RS&L is capable of burying cables 6m deep in the seabed, and its equipment enables it to work up to a depth of 100m. It is looking forward to procuring more equipment to extend its reach so that it can bid for more complex maintenance jobs.
“It is rare to get requests to bury deeper than 6m, so we are able to handle most of the jobs around the region, and we do work in partnership with others in undertaking more complex jobs.
Diplomacy and negotiations are necessary when it comes to landing (connecting) the cables to the shore-based stations as shorelines and coastals are now used and administered by many parties. Other than technical skills, a cable laying contractor needs soft skills such as the ability to persuade and negotiate.
For example, a contractor in South Korea had to negotiate with seaweed farmers before they could land a cable, while in Japan, a settlement had to be reached with the fishing unions. Things can get complicated if you run across oil or gas pipelines (which means more negotiations and permission). One local authority in Israel refused to close off the beach for a short while so that a trench could be dug to bury the cable.
At the beginning of the submarine cable era, there was a widely held belief that the riches of the ocean were too vast to be affected by humans. Apart from shipping and regional fishing, there were few other uses of the sea and most of the marine environment (the little that was known) was still relatively pristine.
In view of the increasingly crowded seabed caused by many competing land uses, governments and authorities are placing more emphasis on regulating cable laying and other infrastructure development plans.
Other concerns include the environmental impact of submarine cable laying in shallow waters as there is some form of disturbance to the seabed due to trench digging and cable burial.
The industry argued that disturbances and impacts caused by cable laying and repairs should be viewed in the context of the frequency and extent of these activities. Clearance of debris from a path proposed for cable burial is usually followed, within days to weeks, by actual burial. Unless a cable fault develops, the seabed may not be disturbed again within the fibre optic system’s design life, which is typically between 20 and 25 years.
Capt Joe Hiew of RS&L Marine is one of Malaysia’s most experienced cable layers/ repairers.
“Furthermore, the once-off disturbance associated with cable placement is restricted mainly to a strip of seabed less than 5m to 8m wide. For comparison, bottom trawl and dredge fishing operations are repetitive and more extensive, with a single bottom trawl capable of sweeping a swathe tens of metres wide in one single passing, and this is likely to be repeated over a year at the same site.
“Cable burial, being a single-impact event, is believed to be much less impactful on the seabed environment compared to continuous, multiple or recurring impacts,” said a report jointly produced by the International Cable Protection Committee (www.iscpc.org), and the United National Environment Programme.
“Laying a transoceanic cable is not much different from pulling a garden hose (about 7mm thick) across the yard. It causes little or no damage whatsover,” maintains Hibbard, who argued that the industry’s low profile was a disadvantage when it comes to asking for protection for cables.
“We don’t go around telling people where the cables are located, but one of the consequence of this is that it can be hard sometimes to convince politicians and administrators to afford adequate levels of protection for the cables. Very few people understand it, and you sometimes get very peculiar interpretations of the laws and regulations. Sometimes you don’t get the necessary clearances, the right of way.”
Man-made damage to cables is not a recent phenomenon. In fact, the industry banded up to set up the Cable Damage Committee back in 1958, and the name was changed to International Cable Protection Committee in 1967 to better reflect the aims of the organisation.
Submarine communications cables are typically 69mm in diameter and weigh around 10kg per metre, with the rule of thumb being the deeper the ocean bed, the thinner and lighter the cable will be. At a depth of a few kilometres, the cable resembles the size of a typical garden hose. The closer the cable is to shore, the thicker it will be as there is a need for more shielding (armour) to protect the cable from various threats such as anchors, trawlers and dredgers.
The Tohoku earthquake (and the ensuing tsunami) that hit north-east Japan last March disrupted communications when many portions of submarine cables were damaged. Some of the cables that make landings in Japan that were damaged included the APCN-2 (an intra-Asian cable that forms a ring linking China, Hong Kong, Japan, South Korea, Malaysia, the Philippines, Singapore and Taiwan), the Pacific Crossing West and Pacific Crossing North, segments of the East Asia Crossing network, a segment of the Japan-US Cable Network, and the PC-1 submarine cable system.
Many cables were damaged at the same time in the same area at depths ranging from 2.2km to 6.4km. A total of 15 breakages were found in three international cables by the four cable ships rushed to the scene.
Though the first cable ship arrived at the site on March 22, the job was completed only on Aug 5. In the end, about 500km of cable needed to be replaced.
The massive repairs required after the Tohoku earthquake were made all the more difficult with the risk of radiation from the stricken nuclear reactors at Fukushima.
According to submarine cable consultant John Hibbard, repairing a damaged undersea cable in deep waters is an amazing feat.
“Attempting to fish out a portion of a cable located at 7km to 8km under the sea using nothing more than feel is an amazing achievement. Just for illustration, it is akin to being in a jumbo jet and looking out of the window trying to find someone’s garden hose. And when you do, you use a rope to pick it up. That is what repairing a deep sea cable is about.”