Soil Burial Tests: Soil Burial of Materials and Structures

In the late 1950s, the Bell System started to bury exchange area plant directly in the soil and now some SO percent of annual additions to service individual homes are buried. By 1975, almost all newly 1 2 T H E BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1972 installed distribution plant will be in this environment. Figure 1, from H. Southworth, 1 shows the trends in the underground, aerial, and buried telephone cable plant over the last sixteen years. The advantages of buried plant over conventional aerial plant are that it is potentially lower in first cost, less subject to service interruptions by natural causes, not affected by trees, faster to install, and more aesthetic. 2 In contrast to this, it is less flexible and additions are costly while workmen in other operations may cause damage to buried lines. In addition, armored cable and wire must be used in rock and gopherinfested areas. In the mid-1950s, the accelerating trend to bury the telephone distribution circuits to homes was thwarted somewhat by problems in the areas of wire and cable design, materials, and construction techniques. The long-range economy of buried plant depends in large measure on the ability of materials to withstand factors in soil environments