Development of 'Man Cage Protection Mat' Significantly Enhances Safety and Workability in Mountain Tunnel Construction

Tetsukensetsu Co., Ltd. (Headquarters: Chiyoda-ku, Tokyo; President and CEO: Masato Imai) has jointly developed a 'Man Cage Protection Mat' that can be retrofitted to drilling jumbos and shotcrete machines used in mountain tunnel construction, together with Nikken Lease Kogyo Co., Ltd. (hereinafter 'Nikken Lease Kogyo'; Headquarters: Chiyoda-ku, Tokyo; President and CEO: Hiroshi Kaneko) and Tekken Kousan Co., Ltd. (hereinafter 'Tekken Kousan'; Headquarters: Bunkyo-ku, Tokyo; President and CEO: Yasuhiro Noshiri).

Background of Development

In March 2024, the Ministry of Health, Labour and Welfare revised its 'Guidelines for Preventing Rockfall Accidents at the Face in Mountain Tunnel Construction,' specifying man cage guards as one of the preventive safety measures. However, conventional steel man cage guards have posed challenges by obstructing work with their support pillars, preventing sufficient proximity to tunnel walls and ceilings.

Usage of the Man Cage Protection Mat

The newly developed 'Man Cage Protection Mat' resolves these issues by adopting a flexible mat structure, enabling close approach to tunnel walls and ceilings. This allows the mat to conform to tunnel cross-sections, significantly enhancing both worker safety against rockfalls and operational efficiency. The product applies the 'Rockfall Protection Mat' manufactured by Tohko Co., Ltd. (Sapporo, Hokkaido), a group company of Nikken Lease Kogyo. It features a three-layer structure composed of foamed urethane and polycarbonate, ensuring excellent safety performance.

Key Features of the Product

The primary feature of the 'Man Cage Protection Mat' is its cantilevered protective mat extending from the center of the cage, which flexibly deforms to match the tunnel's cross-sectional shape, greatly improving wall proximity. Additionally, the mat is covered with a waterproof sheet, expected to improve working conditions even during operations involving drilling slurry, such as rock bolt installation. Furthermore, the product is equipped with a sliding mechanism, allowing adjustment of the mat's position according to the work area. An integrated lever hoist enables height adjustment, ensuring optimal working positions. (Patent pending)

Retrofit Compatibility with Drilling Jumbos and Shotcrete Machines

Future Outlook

The product will begin trial implementation in May 2026 at the Narusegawa Dam Bypass Tunnel Project (Miyagi Prefecture), which Tetsukensetsu is constructing. The company plans to conduct verification and improvements across multiple sites, aiming for full-scale deployment. *The 'Man Cage Protection Mat' is currently preparing for NETIS registration.

Tetsukensetsu aims to contribute to further enhancing safety in tunnel construction projects nationwide through the widespread adoption of this product.