Automated inspection system for large underground concrete pipes under operating conditions

The Emschergenossenschaft based in Germany is currently planning the Emscher sewer system, arguably the largest residential water management project in Europe in years to come. In 2002, the Emschergenossenschaft engaged the Fraunhofer Institute for Factory Operation and Automation (IFF) in Magdeburg, Germany as the general contractor to develop automatic inspection and cleaning systems to meet the requirements stipulated by the legal guidelines. The systems must operate continuously in a sewer line, which has diameters ranging from 1400 to 2800 mm and is partially filled, 25% at minimum, all the time. To construct the Emscher sewer system, the Emschergenossenschaft favors a one-pipe line in long sections. A walk-through or inspection by personnel is impossible in every phase. The Fraunhofer Institute IFF has completed an extensive concept study for the inspection and cleaning systems and has developed as prototypes all systems for motion along the sewer and all sensor s ystems, achieving a new quality of inspection under these difficult conditions. This article describes significant project results and important components of the inspection and cleaning systems such as the inspection systems, pipe axis measurement, system positioning and sensor systems for damage detection. Fundamental for the development of the inspection systems are a detailed inspection going far beyond the video inspection common today and the capability of taking comparative measurements throughout the sewer system's period of operation to describe the development of damage.