Kumamoto Castle
Reconstruction Observation Path

Kumamoto Castle was heavily damaged in the Kumamoto Earthquake of April 2016.
Stone of the Castle were heavily damaged. Nearly 30% of the total surface areas of approximately 79,000 square meters were damaged, and over 10% collapsed. It’s restoration work on the castle will last for about 20 years. The approach of focusing on restoration work while limiting access to the site was considered, but on the other hand, Kumamoto Castle is an important tourist resource, and it was necessary to expand the area open to visitors as soon as possible for the revitalization of the local economy. Therefore, to significantly accelerate the opening of the area to visitors while safely conducting restoration work, the proposal for an observation path was made. The concept of "revealing the restoration work itself" led to not only the development of a new tourist attraction but also a new step towards the future opening of cultural properties.
In order to realize the special observation route, it was necessary to consider challenging design conditions and the landscape of Kumamoto Castle within the restricted area of the historic site. It’s prehistoric site condition with remains of both under and aboveground prohibit either to excavate or to remove tree roots, and the project has to evade where underground remains had been identified. Piling was also forbidden and the foundation was designed as concrete footing on grade. The stone ramparts had collapsed in numerous places and still carry danger from further collapse. The project required sit away from the danger zone. Additionally, since restoration work was planned to continue, it was necessary to provide a separate observation route from the construction route to ensure safety. Furthermore, efforts were made to minimize tree cutting within the site.
Considering these special conditions, a 350m long observation path was established, much like threading a needle. As a result, a large-span arch structure of 50m and a "Ring Girder Structure" were adopted. The framework supporting the floorboards was made thin with a triangular lattice frame, and scenic view points were provided to enjoy the landscape of Kumamoto Castle and the city.