Fujita – Osaka Marubiru Redevelopment ProjectThe Whole Story of Marubiru Demolition Work and the Care Taken for Stakeholder Safety and Security

Demolition work flow

The demolition work proceeded in the same sequence as for typical high-rise buildings: first, confirming and removing hazardous materials such as asbestos; next, dismantling interior fixtures like gypsum board and facilities equipment; and finally, demolishing structural components.
One of the biggest issues faced was the “construction period,” as it was decided that the site would be utilized as a temporary bus terminal during Expo 2025 Osaka, Kansai, Japan. For that reason, it became necessary for a construction period that would normally require two years, to be shortened to one year and six months. Given this, we formulated a plan whereby the structural components would be demolished at a rate of five days per one floor, and thoroughly streamlined work. For loading and unloading components, two tower cranes were operated alternately. By loading the next components while cutting and unloading, we minimized waiting time during operations. Moreover, we employed a two-shift system: during the day, we carried out demolition of structural components such as perimeter slabs and beams, including crushing operations at the ground-level demolition yard; and during nighttime hours, work was limited to quiet operations such as dismantling exterior precast concrete (PC) panels to avoid noise.

Safety measures in demolition work on upper floors

The psychological reassurance that comes with “lack of visibility”

We took great care to cover the building with scaffolding and sheeting so that absolutely no work activities were visible from the outside, striving to create a work site that was not only physically safe, but also visually reassuring. Regarding work at high places, ensuring that the building was “tightly covered” facilitated a sense of safety among nearby residents and those who were passing by.
Of course, in anticipation of any unforeseen circumstances, we took measures to ensure that bolts or debris fragments did not go flying, including by addressing the gap between the sheet and the wall. Even if a bolt were to pop off, the design is such that it would be caught by the sheet and, if it falls to the ground, it would pass within the sheet. Establishing these “second and third lines of defense” was how we took every precaution.

Thorough measures and a mindset to prevent dispersal focused on eliminating third-party accidents

The site of this demolition featured a unique structure built as a regular fifty-two-sided polygon, with scaffolding arranged in a straight-line configuration of regular twenty-six-sided polygons. Therefore, there was an inherent structural issue where gaps inevitably formed at the top of the scaffolding. However, safety was ensured by inserting pliable materials such as rubber or polystyrene foam into these gaps. The work site and the head office came together to seriously address the question, “How can we maximize safety?” In response, we implemented a series of improvements tailored to actual site conditions.
Furthermore, thoroughly implementing detailed safety measures had a positive impact on worker mindset. Over this long-term construction project, consistently demonstrating an unwavering commitment as the prime contractor led to maintaining each worker’s focus and discipline.

Environmental and safety measures in demolition work on lower floors

Noise and dust suppression

The lower floors, which had already been demolished, were used as a crushing yard where we crushed debris that had been lowered from the upper floors. Noteworthy, though, is our work to reduce noise levels by deliberately retaining the outer structural elements of those lower floors. Additionally, the upper section of the crushing yard was designed with dust prevention as the top priority. This involved installing a roof-like curing sheet, while also accounting for the range of movement needed by heavy machinery.
Furthermore, as this project falls under the category of specific construction work subject to noise regulations, at night time we did not use heavy machinery and only performed work that did not generate noise. After cutting the bolts on the exterior PC panels with gas, we lowered the materials using a crane and transported them directly to the disposal site without crushing on the ground level of the site.

Securing the safety of workers

We conducted a rigorous survey to check for asbestos prior to the demolition stage. Although asbestos was confirmed to be present in some areas due to the early construction year of the building, it was completely removed before demolition by heavy machinery began.
Additionally, when performing concrete crushing work on the ground level, all personnel are required to wear dust masks. Moreover, such work is performed while spraying water in order to suppress the risk of dust dispersion. Furthermore, when workers responsible for spraying water need to approach crushed materials, they carry mesh screens used as shields to protect themselves from any potential flying debris.