How important a lifeline mobile telephones have become was brought home to many people in the recent earthquake disaster. Immediately after the earthquake struck on March 11, mobile telephones were unable to connect across a large area, including the Tokyo capital region, the reason being a concentrated and enormous volume of calls “reaching an unprecedented increase of 60 times normal levels.” (Fukushima Hironori, Director of the Disaster Countermeasures Office at NTT DOCOMO) The three mobile operators, DOCOMO, au (KDDI) and SoftBank Mobile, were forced to impose strict service restrictions of maximum 70-90%. Mobile phones were the first choice for confirming safety, a pattern of behavior completely different from the time of the Great Hanshin-Awaji Earthquake.
In addition, all the communications companies suffered unprecedented damage. Many communications facilities were swept away in the tsunami and there were power outages across large areas. Even facilities that had sustained no damages were out of operation. Base stations for mobile phones are equipped with emergency batteries but, normally, they only carry a charge lasting about three hours. From the day of the earthquake to the next day, the number of base stations out of service at the three companies increased to reach a total of about 14,000 stations (among them, 6,720 NTT DOCOMO stations). “We have had many complaints asking why the phones worked immediately after the disaster, but then did not connect.” (Matsuki Akira, Director of the Business Planning Department at NTT DOCOMO Tohoku)
The NTT East Miyagi Kitakami building
destroyed in the tsunami ©WEDGE
According to announcement by the three companies, by early April, the number of base stations out of service had dropped to a total of 1,000 stations (690 stations for DOCOMO as of March 28, 2011). During April, the untiring efforts of all the communications companies normalized communications in nearly all areas. According to tweets in Iwate Prefectures, DOCOMO was first to restore services. Actually, one week after the disaster, when groups of reporters entered Kamaishi City in Iwate Prefecture, DOCOMO was providing normal calling services, much to the appreciation of the Self-Defense Forces and others.
Fuel shortages beyond what was expected“Based on the manual, the Tokyo Head Office took command of the situation and immediately set up the Disaster Countermeasures Headquarters. Before even one hour had passed since the earthquake, systems were in place and work to understand the situation was underway. It was the result of the regular drills.” (Araki Yuji, Director of NTT DOCOMO Tohoku)
The entire DOCOMO Group conducts annual disaster response drills. The premise for the drill in October last year was that an earthquake had struck the Tokai region, something that proved to be of great service for the initial response to this disaster.
Predicting the damage, we conceived of a wide area of personnel and material support including mobile base station vehicles from all branches around the country, and we created scenarios for setting up the Disaster Countermeasures Headquarters and a series of commands and responses, on the basis of which we conducted the response drill. The Disaster Response Office created these scenarios over a period of several months, consulting with external experts and “conducting exhaustive searches to make sure no stone was left unturned.” (Fukushima, Director)
Even so, “the scale of this earthquake disaster exceeded expectations.” (Fukushima) For example, the emergency batteries mentioned previously. The batteries at the base stations stopped and the emergency generators for the relay stations bundled with the base stations ran out of fuel, but it was beyond expectation that the shortage of fuel would extend even to the gasoline for the trucks delivering fuel.
With respect to the base stations that were destroyed in the tsunami, the response included approximately 30 mobile base stations from all over the country and the large zone scheme, whereby a single base station is spread wide and thin to cover multiple base stations. Satellite and micro-wireless circuits were used to deal with the interruptions to the transmission lines linking the superordinate relay stations to the base stations. The micro-wireless circuit is a technology that was used for the second generation of mobile phones before the current third generation that is now in widespread use. “The volume of communications has increased with the third generation, so there has been a shift to optical fiber, but on this occasion, the micro-wireless circuits proved extremely useful for rebuilding the networks at a low cost.” (Matsuki, Director of Business Planning Department)
Incidentally, the damage to transmission lines was also beyond expectations. The backbone transmission lines between dual-system relay stations (optical fiber) were severed in places. Here, it was not possible to use wireless circuits designed for small volumes of communications as a replacement. Not only NTT DOCOMO, but all the mobile phone companies use the NTT East optical fiber network for many transmission lines in the Tohoku region, so we were forced to wait for these lines to be restored. Wireless communications are also dependent on fixed communication networks.Take, for example, NTT East’s Tomioka Building, which lies within a 10-kilometer radius of the Fukushima No. 1 nuclear power plant. On April 13, ten maintenance staff from NTT East, including Nakajima Yasuhiro, the Director of the Disaster Countermeasures Office, and four maintenance staff from DOCOMO headed to the site.
NTT DOCOMO mobile base
station vehicles used at
Higashi-Matsushima City in
Miyagi Prefecture ©WEDGE
By restoring services at this building, NTT East was able to restart operations at another five telephone companies linked to the building, and since the lines used by NTT DOCOMO base stations are stored at the Tomioka Building, we were able to restore services at seven base stations.
Wanting to witness the work of restoring the fixed communications networks that support the base for wireless communications, on April 19, I went to the NTT East Kitakami Building in Ishinomaki City, Miyagi Prefecture to cover the restoration work. Located close to the mouth of the Kitakami River in the northern part of Ishinomaki, the Miyagi Kitakami Building had been reduced to a ruin.
In a system of fixed-line telephones, each household is connected to a subscriber switchboard at the nearest telephone exchange and, also, to a trunk exchange. Then, this is reversed to connect to the destination telephone in the household you want to call. The buildings that house the subscriber switchboard and the trunk exchange are referred to as the “communications buildings.” The communications building that houses the trunk exchange (superordinate building) controls multiple communications buildings where the subscriber switchboards are housed (subordinate buildings). The Kawakami Building is one of these subordinate buildings.
According to NTT East, a total of 41 communications buildings in Iwate, Miyagi and Fukushima Prefectures were completely destroyed or sustained damages from flooding in this disaster. The tsunami had hit the structure of the Miyagi Kitakami Building, destroying the walls, and the inside of the building was a mess of mud and rubble. In addition, since the ground on the site had been gouged out and rubble was everywhere, the crew had prepared a container-like box for housing the SBM exchange. The SBM was installed on a lot rented from JA some distance away.
In front of the Miyagi Kitakami Building, pole construction work was underway. The workers were erecting utility poles to connect the SBM and the building housing the trunk exchange with transmission lines. There were several steel utility poles behind the construction workers. Digging holes one and a half meters into the ground to erect the poles was relentless work in the chill and drizzle. Moreover, it was all done manually. When I asked why they were not using machines, a veteran worker carefully said, “If we use a machine to dig and we find a body under the mud here, what do we do then?” For a fact, right next to us, there were policemen from Gifu Prefecture carrying long poles and searching the ground for bodies.
Maybe because the area was hit by the tsunami, but whenever a new hole is dug, water flows from the ground without stopping. I could hear the worker let out a sigh, “This is hopeless.” When I asked about digging somewhere else, the answer came back, “Since the places for erecting utility poles were decided in consultation with local residents, we can’t randomly change them.”
To stop the walls of the holes from collapsing with the water, resin pipes are inserted in the hole. Even using a steel bar to drive the pipe all the way into the hole from above is hard work. When the young worker said, “It won’t go any deeper,” the veteran worker said, “It will go,” taking his turn with the heavy steel bar. To look at them, the young worker looked the stronger, but when the veteran worker struck at the pipe, it rapidly settled into the ground.
“I think we can dig a bit more with this,” he said and handed over a tool. It was a post hole digger, a special tool only used to dig holes for utility poles. It has two handles, and at the end of the handles, there is a scoop with two blades turned toward each other. When the handles are open, the scoop is also open, penetrating the soil, and when you bring the handles together to close them, the scoop also closes, making it possible to capture the soil. When the veteran worker was digging, the tool spat out mud, but when the young worker tried digging, he mostly scooped up water.
Thinking about the endless hours spent at this work, you really have to take off your hat to them. They were expressly rushed here from Kanagawa where they work for a company affiliated with NTT and, normally, they specialize in laying cables. When I told him how impressed I was, the veteran worker laughed with embarrassment saying, “It’s something I learned in the old days.”
Getting communications links up is not possible without very hard work in a harsh environment and the contributions of many people.
Translated from “Tayorininatta Kunren to beteran no dorokusasa,” WEDGE, June 2011, pp. 26-27. (Courtesy of WEDGE, Inc.)