Intellectual Adventure Series

In Commemoration of the Awarding of the Japan Academy Prize to Distinguished YNU Professor Fujino:
“Bridge for Disaster Prevention to Cross into the Future” (Part 2)

As mentioned in the previous article, the paper (3) on suppression of vibration on the Great Toda Park Bridge and elucidation of synchronization of human walking was neglected and became quietly dormant. It was thought that this paper would just continue its slumber, but….

One day in 2000, the paper on the synchronization of human walking (3) suddenly woke up. The start of this story was another phone call, one that reminded Prof. Fujino of the Great Toda Park Bridge because it was about a consultation on “a pedestrian bridge that sways side to side when it is crowded”. However, unlike the call about Toda Park, this time the call was from London. The voice from the receiver said, “I am calling because I read your paper, Professor Fujino.”

That year, a new bridge was constructed on Thames River to commemorate the millennium. Named the “Millennium Bridge”, it was supposed to be a new spot to celebrate the beginning of the new millennium . However, after the opening ceremony, the bridge vibrated once people started to cross. It was an unexpected side-to-side swaying. The amplitude reached a maximum of 10 cm and the bridge was closed down just 2 days after its opening. This news spread throughout the world, together with images.

“We have to mitigate the vibration and reopen the bridge as soon as possible. So, we looked for previous researches, but as far as we can tell, Prof. Fujino, you are the only one who has written a paper about it. Would you please participate in the investigation and give us advice?”

Just by watching the video, Prof. Fujino could tell that is was synchronization of human walking. He was called in as an advisor and held discussions with engineers. He advised them about installing dampers. the bridge reopened18 months later, in March 2002 (4)(5).

As a result, Prof. Fujino's name resounded all over the world. His achievements were even written in a textbook on bridge engineering (Figure 4) and the synchronization of vibration by pedestrians on a bridge was explained in a science book for the general public (Figure 5).

Figure 4. Textbook “BRIDGES” (4) Cover and description of synchronization of human walking (P6), (underlined by this article’s author), Figure 5. “SYNC”, a science book for the general public (2)

Shueisha Shinsho’s “Non-linear Science: The Synchronizing World ” (6) provides an easy-to-understand explanation on vibration caused by groups of people. This book also comments on the Great Toda Park Bridge and the Millennium Bridge, together with the role that Prof. Fujino played (Figure 6).

Figure 6. Shueisha Shinsho “Non-linear Science: The Synchronizing World” (in Japanese)

Looking back, Prof. Fujino fondly reminisces about those times.

“If I hadn’t been in Toda Park, or if I hadn’t written a paper in English, who knows what could have happened? Back then, some people were astonished at what I was doing and would ask me, “Why are you working on something like footbridges? Why don’t you work on long-span bridges?” Why? - Because I thought it was an interesting work, but didn’t think it would become a major work. It is all very mysterious. Now, I can only say it is important to write papers even about small things!”

Back to the present, Prof. Fujino is the Principal Investigator for the research unit of “Safety and Resilience of Infrastructure and Infrastructure Systems” at the Institute of Advanced Sciences (IAS), YNU, and he is leading research on urban disaster prevention. “Even if bridges did not break, transportation would still stop if roads were blocked. It is necessary to also look at things other than bridges, such as traffic signs falling and cars overturning.”

Based on this belief, at YNU, he leads an industry-academia collaborative research titled “Research on Prediction of Damage and Measures Against Mega-Earthquakes Such as Tokyo Inland Earthquakes” with the Metropolitan Expressway Co., Ltd (Metropolitan Expressway) and “Risk Management in Expressway Facilities and Operation” with the East Nippon Expressway Co., Ltd. (NEXCO East).

Among these, those that are mainly led by staff at the IAS are “Risk Assessment of Expressway Transport of Vehicles Carrying Hazardous Materials”, a collaborative research with the Metropolitan Expressway involving Professor Atsumi Miyake (Deputy Director of IAS and Principal Investigator for the research unit of “Safety Engineering and Risk Management of Energy Systems”), and “Pre- and Post-Risk Management After Earthquakes and Other Disasters”, a collaborative research between Professor Kazuhiko Noguchi (Director of the Center for Creation of Symbiosis Society with Risk, IAS) and NEXCO East. Examples of studies involving institutes other than the IAS are “Investigation of the Impact on Industry of Blocking Traffic on the Metropolitan Expressway After an Earthquake” between the Metropolitan Expressway and Associate Professor Taku Ishiro (Graduate School of International Social Sciences), and Associate Professor Mamoru Kikumoto (Graduate School/Faculty of Urban Innovation (IUI)) predicting the range of liquidation of the ground after an earthquake. Other than these studies, many staff members at IAS/YNU are participating in collaborative research projects (7).

Now, let us discuss why Prof. Fujino chose IAS as his base for various collaborative research projects through his own words.

“I am more suited to organizing a lot of people to work, rather than diligently working on my own. The role of IAS is to make YNU more active. There is more power if we try things by combining various researchers in YNU. We have the potential, so it is possible if we work hard.”

Other than “synchronization of human walking”, Prof. Fujino’s achievements for the Japan Academy Prize also include “structure control” and “health monitoring”. Let us see what these mean as well.

“Structure control” is the technology for preventing disasters by installing dampers and aseismic/seismic isolation systems for structures such as bridges using knowledge on control engineering. “Health monitoring” is the technology for observing deterioration over time and the effect of earthquakes and transportation by installing accelerometers on bridges and other structures.

As an example that is deeply connected to Yokohama, over 30 accelerometers were installed on the Yokohama Bay Bridge to conduct measurements on over 80 types of ground movements and responses to accurately investigate the behavior of the bridge during an earthquake (8). This has led to better preparations against earthquakes.

In this way, Prof. Fujino has pioneered new fields by fusing knowledge of other research fields, such as control and measurement, with civil engineering. He thinks that this suits his style.

“Among researchers, there are the type who dig deep into their field of expertise and the type who venture into new places by connecting their field of expertise with other fields. I am the latter type,” he said.

Prof. Fujino worked on this type of research from in the early 1990s. His research has now developed into a new discipline “infrastructure disaster prevention and urban disaster prevention”. It has become popular through the Great Hanshin-Awaji earthquake (1995), Great Eastern Japan earthquake (2011) and a terrible highway accident caused by the collapse of Sasago Tunnel (2012).

It may be appropriate to think that the professor had good foresight, but Prof. Fujino humbly claimed that, “I only conducted the kind of research that I thought should be done. All the attention just came afterwards”.

So, what sort of research is “research that should be done”? Prof. Fujino said that, “Research that should be done is research that is interesting and research that is helpful to society. If it is either, that research is worth doing.”

In order to do such researches, he said that, “Essences to create new things are encountering diverse cultures and ways of thinking, and ideas from the study and research of other fields. However, make your home base to depend upon first, it is important to deepen your knowledge in your own expertise.”

The final figure, the watercolor painting titled “Yokohama Bay Bridge” (Figure 7), was painted by Prof. Fujino when he attended a landscape painting class with students. He said that paintings were helpful in understanding the characteristics of bridges because unlike photographs, they could have dramatic exaggerations and deletions.

Figure 7. Yokohama Bay Bridge (2015, Yozo Fujino)

Note: This article was written based on an interview with Prof. Fujino in April 2019 and by referring to supporting documents and materials. Prof. Fujino’s words have been edited and reconstructed. The reference numbers and figure numbers are serial numbers that continue from the first half of the article.

What are your thoughts after reading this two-part series, In Commemoration of the Awarding of the Japan Academy Prize to Distinguished YNU Professor Fujino, “Bridge for Disaster Prevention to Cross into the Future”? With the remaining space, I would like to write about my thoughts.

The word “innovation” did not appear in this article at all. Prof. Fujino never mentioned it as well. However, as I investigated the reference materials and actually started writing this article, I got convinced that this is true innovation. By combining bridge engineering and control engineering, he created new fields called structure control and structure health monitoring. They have spread widely throughout the government and industry as something that is beneficial to society. What other word would be appropriate to express such achievement other than “innovation”? Maybe really important innovations happen without us realizing them as such.

1. The Japan Academy
2. Strogatz, S. (2004). Sync: The emerging science of spontaneous order. Penguin UK.
3. Fujino, Y. et al. “Synchronization of human walking observed during lateral vibration of a congested pedestrian bridge” Earthquake Engineering and Structural Dynamics. (22) 741-758 (1993) 4. David Blockley “Bridges: The science and art of the world's most inspiring structures” Oxford University Press (2010)
5. Fujino, Y, (2007). An experience on vibration problems in Millennium Bridge, London. In Japanese.
6. Kuramoto, Y. (2014). Non-linear Science: The Synchronizing World. Shueisha Shinsho, in Japanese.
7. IAS Research unit: Safety and Resilience of Infrastructure and Infrastructure Systems
8. Uokohama National University (Eds.)(2018). RISK KYOSEI. Maruzen Publishing.

(Masahiro Nakagawa, IAS Strategic Planning Manager)