OSAKA, Aug 28 (News On Japan) - Ahead of Disaster Preparedness Day on September 1, NTT West opened to reporters an underground cable-tunnel network in Osaka that supports the city’s communications infrastructure. At its deepest point the tunnels run 40 meters below ground and house about 10 million fiber-optic lines and 6 million telephone lines.
Spanning roughly 100 kilometers beneath Osaka Prefecture, the network is equipped with fire- and water-resistant doors, flame-retardant cable covers made from materials similar to firefighters’ gear, and automatic drainage pumps. The covers are rated to withstand temperatures of up to 840°C, and the structure is designed to endure an earthquake with a seismic intensity of 7 on the Japanese scale.
For security, the exact locations are not disclosed and access is restricted to a limited number of NTT Group employees. The facilities are inspected and renewed regularly so they can continue operating during disasters, underscoring the often unseen systems that keep communications running.
Source: Television OSAKA NEWS















