Conduit inspection robot and small conduit after-laying method

The construction of a new optical fiber cable communication system involves the costly operation of installing the cables underground, and, in addition, such installation work is subject to numerous regulations. It is therefore preferable, to incorporate new optical fiber cables within existing conduit, into which power cable has already been installed. However, if any collapse or blockage has occurred within the existing power cable conduit, this may make the inclusion of optical fiber cables impracticable. Therefore, it is necessary to have a device which is capable of inspecting the condition inside of the existing power cable conduit, prior to the optical fiber cables being installed. Tokyo Electric Power Company and Fujikura Ltd. have jointly developed the self-advancing conduit inspection robot, and the `small conduit after-laying method´ for including a small conduit for optical fiber cables, within an existing power cable conduit. The authors describe the robot and experience with it in practice