Meidensha: Creating a better future with our people and technology.

This content is a reprint of "Meidensha: Creating a better future with our people and technology"
that was posted in the Nikkei Online Edition from March 2019.

Meidensha: Creating a better future with our people and technology.

Stage8 Using IoT to combat sudden localized downpours Inundation monitoring technology for community protection Visualization of the underground world in Kumamoto, an area of abundant water resourcesStage8 Using IoT to combat sudden localized downpours Inundation monitoring technology for community protection Visualization of the underground world in Kumamoto, an area of abundant water resources

Localized downpours occur frequently all over Japan. Urban areas have seen many instances of flood damage when water suddenly surges out of manholes. The living environments of communities in Japan are protected by sewer networks having a total length of 470,000 kilometers, even greater than the distance from the earth to the moon (380,000 kilometers). However, unexpected heavy rainfall due to abnormal weather can quickly overload a sewer network. Sewer maintenance and repair costs are expected to rise to ¥1 trillion per year, a worrisome problem for the national government and local governments. As a manufacturer of heavy electric equipment, Meidensha has supported water and sewage treatment infrastructure. The company uses cutting-edge information and communication technologies (ICT) to develop new anti-flooding solutions.

"Our house is about to get flooded at any minute due to heavy rains. Please bring sandbags immediately." Hitoshi Fujimoto, Director of Pipeline Maintenance Section of Maintenance Management Department at Kumamoto City Waterworks and Sewerage Bureau, sincerely responded to upset residents whenever heavy downpours struck. He piled about 300 sandbags at the site, and even worked to remove them afterward.

Kumamoto is traditionally known as the "land of fire," but it is also an area of abundant water resources. Unlike any other city with a population of over half a million in Japan, Kumamoto City relies on only groundwater for all of its tap water. With abundant groundwater from the western slopes of Mount Aso, Kumamoto City is dubbed "a town where mineral water flows from every faucet" and has never run out of water, even during a drought. Groundwater still wells up from the Kengun water source in the eastern part of the city, supplying a quarter of the tap water.

Hitoshi Fujimoto
Hitoshi FujimotoDirector
Pipeline Maintenance Section
Maintenance Management Department
Kumamoto City Waterworks and Sewerage Bureau

In the meantime, sudden localized downpours, such as the torrential rain that hit northern Kyushu, have been occurring more and more frequently every year. Rainfall intensity was recorded at up to 65.5 mm/hour in June 2001, 80.5 mm/hour in July 2003, and 86.5 mm/hour in June 2006. Many sudden localized downpours of over 60 mm/hour were causing significant problems. Mr. Fujimoto often traveled to see and photograph streets and roads flooded so severely that they looked like rivers. Using the footage he had shot, wearing out three video cameras in the process, he gave a presentation to the mayor and explained the importance of flooding countermeasures. His efforts were successful, and in 2008 Kumamoto City developed a plan for flooding countermeasures in sewerage works.

Heavy rains in August 2013 flooded the basement of apartment buildings in central Kumamoto City, and cars were submerged. Faced with the need for further disaster prevention measures, Mr. Fujimoto reflected, "We considered hardware-side measures such as upgrading rainwater pipes and rainwater retention pipes, but I decided that we needed, first of all, to determine and visualize the existing situation including water level changes in sewer pipes. Rainwater flows downhill from higher to lower elevations and into rivers, but the city's sewer network extends a total of 2,600 kilometers, nearly as far as from Kumamoto to Hokkaido. This made it difficult to determine the situation inside sewer pipes by conventional means."

Developing a smart manhole cover for flood monitoring; predicting water levels one hour in advance

Jointly with Meidensha, Kumamoto City began demonstration testing of a water level prediction system using IoT in June 2014. Meidensha worked on developing a smart manhole cover, an IoT device for sewer pipes. In conjunction with sensors installed in sewer pipes to monitor water levels in there, the antennas attached to manhole covers receive the data from the sensors and send them in real time to the cloud. The objective is to use artificial intelligence (AI) to predict water levels one hour in the future, based on information on water levels in sewer pipes combined with rainfall information and other data, and send this information by way of local governments in particular to residents, shops in underground malls, and others to protect against inundation.

Smart manhole cover mechanism for flood monitoring and countermeasures

"Of course we'll need to upgrade infrastructure on the hardware-side, but that will take time and money. It has to be done in combination with software side measures using ICT," said Mr. Fujimoto. With sudden localized downpours on the rise, a new vision for sewer infrastructure issued by the Ministry of Land, Infrastructure, Transport and Tourism calls for actively using ICT in disaster prevention and mitigation.

Meidensha engineers were working on a manhole near JR Kumamoto Station on the morning of December 14, 2018. They opened the manhole cover, weighing about 50 kilograms. There was a communication device fitted with an antenna and battery on the back of that heavy cover. "We can see the water levels in sewer pipes in real time. It's only seven or eight centimeters right now, but the level can quickly rise to more than two meters during the rainy season," explained Ryutaro Kawaguchi of Meidensha's WIS System & Business Development Section, WIS Product & Ecosystem Development Division, Water Infrastructure Systems (WIS) Business Unit, while showing past water level data records on the screen.

This is a combined sewer pipe for rainwater as well as sewage. Warm air is drifting through the pipe, but there is hardly any odor. Looking down from above, it appears that the water is flowing just down below, but it's actually about five meters from the bottom of the sewer to the manhole cover. Kumamoto City is not a place that most people would associate with inundation damage. However, the Japan Meteorological Agency finds it extremely difficult to predict the times and locations of localized heavy downpours caused by abnormal weather. "Inundation damage may occur even in places that do not experience heavy downpours, because the sewer network is complicated and there are issues of topography as well. It is very difficult to predict the water levels. Inundation monitoring is very important for the area," Kawaguchi emphasized.

Ryutaro Kawaguchi
Ryutaro KawaguchiWIS System & Business Development Section
WIS Product & Ecosystem Development Division
Water Infrastructure Systems (WIS) Business Unit

Demonstration testing in a sewer pipe subject to many risks; Creating a robust system through trial and error

Mr. Kawaguchi, who is from Kyushu, has witnessed disastrous flood damage. He recalled, "I have a friend whose house was washed away due to the heavy downpours that hit northern Kyushu in 2017. Drifting timber and all kinds of debris were washed from the Chikugo River into the Ariake Sea. All around, it was a terrible sight." As a student, he lived in Saga, in an area that has many small waterways called "creeks," and frequently experiences flood damage. After joining Meidensha, he wound up participating in demonstration tests of a water level prediction system in Kumamoto starting in 2013, encountering one difficulty after another. In addition to multiple torrential rainstorms, the Kumamoto earthquakes struck in 2016, damaging part of the sewer system.

There are essentially many dangers inside sewer pipes. There are risks of anoxia and hydrogen sulfide poisoning due to toxic gases, so a toxic gas detector is always used to check inside the pipe, and special qualifications are required for work inside sewer pipes. "There is a harsh environment inside a sewer pipe, with high heat and humidity. I entered that environment hundreds of times for repeated testing. Sometimes the equipment was damaged and became unusable," he said.

Many risks lurk inside sewer pipes.

Mitsuhiro Nakashima, General Manager for Special Task of WIS Product & Ecosystem Development Division, Water Infrastructure Systems (WIS) Business Unit, who promoted the development of the smart manhole cover, explained, "We needed to install the antenna on an iron manhole cover, but the iron cover was not very compatible with radio waves. We placed the antenna on the upper side of a manhole cover in a public road, so it needed to be able to withstand the weight of passing cars. Sensors to measure the amount of water are placed at the bottom of the sewer pipe, but in large cities, some sewers are more than 50 meters deep and 6 meters in diameter. Because large volumes of water flow through at once, of course, we needed to find ways to ensure that the communication devices, batteries, sensors, and other equipment could withstand intense water pressure."

Meidensha partnered with a variety of municipalities, engaging in trial and error to develop a robust and highly reliable smart manhole cover system. Our demonstration testing began with installation of a prototype in a sewer in Tokyo in 2013, and in Kumamoto City a joint research was performed with demonstration testing at a total of 14 manholes.

Mitsuhiro Nakashima
Mitsuhiro NakashimaWIS Product & Ecosystem Development Division
Water Infrastructure Systems (WIS) Business Unit

Using front-line capabilities to develop a water level prediction system; over 80% accuracy

As sudden localized downpours cause increasing problems in society, other IT service companies are offering similar systems for inundation monitoring. "Even IT service companies can get involved if just a supply of communication systems such as clouds is called for. However, Meidensha has supported water and sewage infrastructure nationwide for many years, including electrical equipment for sewage treatment plants. Therefore, we have first-hand information from the field. We understand which points should be measured to obtain effective data. Our strength lies in our front-line capabilities," said Mr. Nakashima.

Meidensha commenced sales of smart manhole covers in 2016. This technology can be used by simply replacing a manhole cover. Costs were reduced through smart use of battery power and the latest communication technologies. Mr. Nakashima said, "We can predict the water level one hour in advance with an accuracy of over 80%. The level of radar weather forecasting by the Japan Meteorological Agency is expected to improve in the future, contributing to even greater accuracy. To allow vulnerable persons such as the elderly to evacuate smoothly, we want to be able to offer highly accurate water level predictions not just one hour in advance, but two or three hours in advance."

In addition to ensuring the safety of the community, rapid forecasting of water levels can have additional benefits. Analyzing the accumulated data will make it possible to determine which sewers need to be upgraded first. This will also contribute to the effective utilization of existing equipment. According to Mr. Fujimoto of Kumamoto City, "Optimizing the operational management of pumping stations based on water level forecasts could help to improve the efficiency of sewer maintenance, thereby reducing costs."

Meidensha's front-line capabilities are a great advantage in supporting water infrastructure.

Applications in tourism and medical care in addition to disaster prevention; Promoting data sharing

"I think it is highly meaningful to be able to visualize information under the ground that could not be seen in the past," said Kazuyuki Hirai, General Manager, WIS Product & Ecosystem Development Division, Water Infrastructure Systems (WIS) Business Unit. He is also the project team leader for the Public Sector Infrastructure Project Planning & Support Office of Meidensha. Information from inside sewer pipes may have applications in a variety of fields, in addition to disaster prevention. Even when some roads are likely to be flooded by localized downpours in a certain area, the sun may be shining in a neighborhood area where there is no impact on traffic. Connecting water level forecast information with traffic information could be beneficial for fields such as tourism and logistics," he said. Microorganisms could be monitored inside sewers for early detection of infectious disease outbreaks, and this could be used to help develop a support system for medical care that would send information to the community.

Using electric technology, Meidensha has supported various types of infrastructure including water and sewer systems and railways. Mr. Hirai emphasized, "We are not planning to keep all of the data we have gathered through infrastructure to ourselves. We want to share this data with the national government, local governments, and other companies, etc. for uses that benefit the community." "For example, when tens of thousands of people gather at some event such as a soccer game, they will all use the toilets and check their smartphones at halftime. That places a heavy load on sewage treatment and radio frequencies. Then when the event is over, the roads and railways will become very crowded. It should be possible to prevent or reduce problems before they happen by predicting these kinds of information and allowing each type of infrastructure to get prepared in advance in a coordinated way," he said.

Kazuyuki Hirai
Kazuyuki HiraiWIS Product & Ecosystem Development Division
Water Infrastructure Systems (WIS) Business Unit

In Minami Aso Village, which was afflicted by the Kumamoto Earthquake, evidence of landslides can still be seen. Bridges, roads, railways, and other infrastructure have not yet been completely restored. Natural disasters such as earthquakes and torrential rainstorms may strike at any time. However, using infrastructure IoT devices to collect and share various types of data may contribute not only to safety and peace of mind for the community, but also to stable and efficient operation and management of a variety of services.


Sewer system construction progressed rapidly in Japan beginning in the 1970s, attaining a coverage rate of 78%. Public sewer systems are used by 100 million residents of Japan. The service life of a sewer system is generally 40 years. Most of them are due for equipment upgrades, but this is difficult for municipalities facing financial challenges. Meidensha's share of electrical equipment for sewers is about 18%; sewage for as many as 18 million people is treated using Meidensha equipment. The sewer water level prediction system that Meidensha has developed, based on many years of experience and expertise along with the latest IoT technologies, is expected to help minimize inundation damage and promote smart rainwater management.

Meidensha ICT solutions

Explanation of terms

IoT devices for infrastructure
There has been explosive growth in devices that are connected to the Internet, known as IoT devices. The scope has expanded from information terminals such as smartphones and PCs to cars, home appliances, offices, and manufacturing sites, and also to infrastructure, including water and sewer systems and roads. IoT devices for use in infrastructure include sensors, antennas, and other communication devices. However, in order to put them into practical use, difficult challenges must be overcome. In many cases, the communication environment is challenging, and the devices must stand up to many years of use. Therefore, we use LPWA, the latest in wireless technology, for long-distance data communications with low power consumption.
*Honorifics omitted.

Meidensha: Creating a better future with our people and technology.

  • Stage1 Powering the excitement.
  • Stage2 Protecting water resources and infrastructure that nurture the community.
  • Stage3 Driving force for a new automotive era.
  • Stage4 Pursuing greater safety and stability in railway transportation.
  • Stage5 AI for water treatment protection.
  • Stage6 Efficient energy management.
  • Stage7 Lightning Protection.
  • Stage8 IoT to protect from heavy rain.
Return to the top of this page