Overview
TOKYO—Toshiba Corporation has developed technology and unified evaluation method for analyzing and visualizing the hidden interior damage of concrete bridge decks and determines internal soundness. The technology compensates for factors such as vehicle weight, speed or bridge structure.
In 2022, Toshiba developed a technology that analyzes and visualizes the internal soundness of bridge decks, and demonstrated its effectiveness with bridges on the Fukuoka Expressway in Kyushu, Japan, operated by the Fukuoka-Kitakyushu Expressway Public Corporation (Fukuoka Expressway Corp.)*. The technology uses sensors installed on the undersurface of the deck to acquire and digitize data from weak waves generated at the road surface as vehicles cross the bridge, analyzes the data to digitize internal damage and visualize as a soundness map.
In order to bring the technology into wider application, it was first necessary to validate its consistency in many different conditions. Continuing to work with Fukuoka Expressway Corp, Toshiba carried out verification tests on a test bridge and confirmed that, while different conditions yield variable evaluation results, the application of suitable adjustments realizes stable assessments. The refined technology enables evaluations of the internal soundness of a bridge based on a unified criteria, and makes it possible to tailor repairs to the condition of individual decks, and to validate repair effectiveness. Promoting the digitization of the technology will enhance maintenance efficiency and contribute to the long-term sustainability of social infrastructure.
Toshiba, working with Toshiba Plant Systems & Services Corporation, aims to launch a bridge maintenance survey service for concrete bridge decks in FY2024 (to the end of March 2025).
Development background
There is a growing global need for sustainable infrastructure maintenance, as many bridges, tunnels, and roads built during periods of rapid development are now aging and require attention and repair to maintain their safety and longevity. In Japan, a significant proportion of transport infrastructure is over 50 years old, and the challenge of delivering comprehensive maintenance is further compounded by workforce shortages.
A tragic 2012 ceiling collapse in the Sasago Tunnel on the Central Expressway in Yamanashi Prefecture, about 80-kilometers west of Tokyo, underscored the importance of proactive and efficient maintenance. It led to a wider understanding of the urgent need to optimize resources by adopting advanced maintenance technologies, and to regulatory reviews and updates.
Bridge deck deterioration is usually assessed through external visual inspections, which guides decision-making on what to repair and the methods to use. However, it remains difficult to detect internal deterioration and its progress from exterior appearances alone. It is also difficult to prioritize what to repair as part of a well-balanced maintenance plan, and to assess effectiveness once repairs are completed. If decisions could be made on the basis of internal damage as part of a maintenance plan with ordered priorities, repair work would be more effective. Beyond this, the ability to confirm internal improvements after repair would help to minimize any overlooked internal damage, and avoid the need for repeated repairs, promoting more efficient infrastructure maintenance.
Toshiba took on these challenges by developing a technology that visualizes deterioration, particularly internal damage invisible to exterior evaluation, and demonstrated its effectiveness in joint demonstrations with Fukuoka Expressway Corp. The next step was to arrive at systems for real-world conditions—with varied vehicle types and differing bridge structures—and to develop an evaluation method that applies consistent criteria across diverse conditions.
Features of the technology
In partnership with Fukuoka Expressway Corp., Toshiba conducted simulations on a 750m test course with a bridge. This setup allowed for controlled tests under various vehicle conditions, which are difficult to replicate on actual bridges. The testing used different concrete bridge decks and road pavement that replicated actual highway conditions, and vehicles of different weights driven at a range of speeds. The results revealed that factors like vehicle weight and pavement type impacted on the degree of damage shown on the soundness, making it appear stronger or weaker. Using this as a guide to appropriate adjustments to evaluations confirmed that the technology can be applied to different bridges and that it accurately assesses the internal soundness of bridge decks.
For example, heavier vehicles tend to lead to underestimations of damage levels, so the evaluation is adjusted by taking into account the percentage of heavy vehicle traffic on each bridge. Conversely, vehicle speed had little effect on results, except during severe congestion when speeds are exceptionally low, meaning no adjustment is typically necessary. By incorporating statistical data on bridge traffic volume and structural differences, the technology realizes unified evaluation method across diverse bridge conditions.
The technology facilitates the identification and visualization of internal bridge deck damage that cannot be confirmed through standard visual inspections, contributing to the extension of social infrastructure lifespan through efficient and appropriate repairs.
Future developments
Toshiba, with Toshiba Plant Systems & Services Corporation, aims to introduce a bridge maintenance survey service by the end of FY2024, which can also be applied to a broad range of concrete structures beyond bridges. Toshiba will seek to make the technology the standard in civil engineering, contributing to a circular economy and the digital transformation of infrastructure maintenance.
The developed technology includes outcomes from the “Robot and Sensor System Development Project for Infrastructure Maintenance and Disaster Surveys,” a research project commissioned by Japan’s New Energy and Industrial Technology Development Organization (NEDO).
- Toshiba press release announced in July 2022
https://www.global.toshiba/ww/technology/corporate/rdc/rd/topics/22/2207-01.html