In January 2025, a prefectural road cave-in accident occurred in Yatsushiro City, Saitama Prefecture, prompting NTT East (Tokyo) to innovate a technology aimed at early detection of cavities that may lead to such incidents. The breakthrough utilizes communication optical fiber cables located beneath roads as 'sensors,' marking a significant advancement in infrastructure monitoring.
The development comes in response to the growing concern regarding road safety, as approximately 10,000 road cave-ins happen annually due to the creation of voids caused by damages to underground utilities like sewage pipes. The new technology is expected to enable the detection of cavities deep underground, which are often challenging to locate using traditional radar techniques from the surface.
NTT East has initiated the application of this innovative method, targeting a one-year timeline for operational deployment. Optical fiber cables, typically installed about 1 to 2 meters underground, will measure vibrations transmitted through the surrounding ground., specifically those caused by vehicle traffic. This data will help the company detect changes in vibrations due to cavities’ presence and the movement of soil or sediment.
In February 2025, the company commenced collecting vibration data in a section of approximately 1.8 kilometers in Saitama Prefecture, where sewage pipes run in a parallel alignment with the cables at approximately 7 meters underground. This real-time monitoring aims to analyze how effectively this technology can identify anomalies associated with underground voids.
According to the Ministry of Land, Infrastructure, Transport and Tourism, the challenges posed by subterranean cavities, especially in urban areas where utilities lie deeper, necessitate reliable detection methods. With approximately 490,000 kilometers of sewage pipes across Japan, the innovative nomethod NTT East employs could revolutionize how the aging infrastructure is managed and potentially prevent future road cave-ins.
"This technology will allow for the exploration of the deterioration conditions of water, gas, and electric conduits beneath roads," NTT East communicated in an official statement. "We aim to connect this innovation with the realization of sustainable infrastructure."
The application of this technology, if successful, could prove critical in addressing the urban infrastructure's vulnerabilities and enhancing road safety. As NTT East continues to analyze movement data and collaborate with local governments, the pressing question remains: can this method effectively resolve the issue of undetected voids that lead to dangerous road conditions?
Given the structure of Japan's older urban environments and the labyrinth of underground utilities, this technology could serve as an invaluable tool. It underscores a proactive approach not simply to respond to accidents after they occur but to prevent them through innovation and smart monitoring.
As NTT East gathers more data and refines its processes, there will undoubtedly be a keen interest in its success not only in Saitama Prefecture but potentially in urban settings across Japan where similar issues lurk beneath the surface. The integration of communication technology into civil engineering represents a modern shift that could redefine infrastructure paradigms and ensure safer, more resilient road networks for the future.
