An amazing number of wires and pipes have been installed underground to distribute electricity, gas, water and telephone signals. The network keeps growing in Japan, making good use of subterranean space in a country where land is scarce.

Tokyo Gas Co., Ltd., provides district heating and cooling services through underground pipes, mainly in Greater Tokyo. For example, under the streets of Shinjuku, an important business district, pipes about 2 km long carry steam and chilled water through tunnels that are approximately 4 m in diameter. Both are used to keep offices at a comfortable temperature. The steam is heated at one place, making it possible to use the exhaust heat and ensure centralized control, for greater efficiency.

Wires, too, are going underground to serve the telecommunications industry. The two largest telephone corporations in Japan, NTT East and NTT West, have constructed tunnels for cables in different parts of the country. The tunnels have a total length of 641 km, and are located about 10 m under the ground. Inside the tunnels, masses of optical fiber cables and wire bundles are strung along the walls, leaving only enough space for one person to pass. Fiber optics have become a key element in telecommunications in Japan, and underground tunnels help ensure uninterrupted service.