Patent ID: 7179019

Claim:
A method for laying communication cables in an underground pipeline wherein one or more branch pipes branch off from a main pipe constructed between pits and the communication cables are laid through the main pipe and the branch pipes, characterized in that, a plurality of high-strength low-elongation tension members, including at least one each of a trunk tension member and a branch tension member, are disposed along a trunk communication cable laid in the main pipe and a branch communication cable laid in a branch pipe, the tension members being slidable in the lengthwise direction with respect to each communication cable, and then each communication cable is inserted into the main pipe and the branch pipe by drawing in the trunk tension member placed along the trunk communication cable from one pit to the other pit within the main pipe and the branch tension member placed along the branch communication cable from said pit to a branch pipe box through the main pipe and the branch pipe, and subsequently each communication cable is laid in the upper space of inside the main pipe by tensioning each tension member thereby stretching the tension members inserted in the main pipe substantially straight in the upper space of inside the main pipe, and also the branch communication cable is laid in the branch pipe in such a way that it is prevented from becoming loose by tensioning the branch tension member inserted in the branch pipe.