The SHANTI COST Action has coordinated research efforts on data harmonization for transport surveys across Europe. Guidelines for harmonizing surveys are not only a statistical problem, because each country also needs to analyze survey results throughout time (time series in the perspective of previous surveys on the same thematic issues with normally the same design) and changing the protocol or the definitions may have an impact on indicators in the sense that the changing behavior could be confused with changes in methodology. Therefore a bottom up approach relying on the skills of the researchers involved in the field of national travel surveys and so quite well knowing their particularities sounds more promising and could lead to more acceptable guidelines. To make results of different survey approaches comparable - it is necessary to develop a methodology or heuristic in which way a transition from one design to another can be derived and how the results of either survey approach can be "translated" or transformed into the results of another