This is the first of a series of papers on a consistent model independent analysis of the complete experimental information on the reaction πN → ππN at pion momenta up to 500 MeV/c. The paper summarizes the theoretical approach and details of the computational procedure. The complete database on total cross sections in 5 ππN channels is given together with a critical discussion of their model independent analysis. * This work was funded by the Deutsche Forschungsgemeinschaft (DFG), Bundesminister für Forschung und Technologie (BMFT), and the Kernforschungsanlage Jülich (KFA) and Russian Ministry of Education Grant G13.018 0