Chugai Technos Corporation

The Atomic Bomb Dome, a symbol of peace in Hiroshima, the site of the atomic bombing, is a building that was exposed to radiation from the first nuclear weapon used in human history during World War II. It was registered as a UNESCO World Heritage Site in 1996.
Since the first preservation work was carried out in 1967, a total of five preservation works have been carried out up to the present (2024). In addition, since 1992, a "soundness survey" has been carried out every three years to check the deterioration of the bricks and mortar of the exterior walls.
In order to solve the issues that have arisen with traditional soundness surveys, we are working on our survey work by making full use of new technologies such as drones.

In previous inspections of the structure's integrity, scaffolding was set up all over the Atomic Bomb Dome, which was then covered with sheets to conduct a close-up visual inspection.
As a result, the Atomic Bomb Dome was not visible during the several months that the survey was conducted, causing disappointment among many tourists who had traveled far away.
In addition, the transportation and installation of scaffolding materials placed a heavy burden on the Atomic Bomb Dome and its foundation, which are required to be preserved for the long term as a World Heritage Site.

Hiroshima City, the client, has begun conducting health inspections using drones since fiscal 2024, replacing the traditional close-up visual inspections using scaffolding.
Our company, which is in charge of the survey, took photos using a large drone (DJI Matrice 300 RTK) to survey the exterior of the Atomic Bomb Dome, and a small drone with collision prevention capabilities (Skydio 2+) to survey the interior. This allowed us to check for cracks of 0.2 mm or more, and to compile a soundness survey with the same accuracy as a conventional close-up visual inspection.
Drones cannot perform the hammering inspections that were previously performed in parallel with conventional close-up visual inspections. However, by eliminating the need for scaffolding, the drones can carry out the inspection while solving major issues such as minimizing the impact on tourists and the damage to the building itself.