The H.U.S.H. (Harmonization of Urban noise reduction Strategies for Homogeneous action plans) project moves from the evidence that harmonization of noise action planning methods is needed, not only in Italy but also in all the European countries where a former Legislation about noise planning was existing at the moment of Environmental Noise Directive (END) 49/2002/EC adoption. The general aim is harmonizing national noise management standards with END for obtaining homogeneous noise Action Plans, in order to give contribution to the more general need of transposing, implementing and enforcing a common or harmonized environmental legislation among EU countries. Specific aims of the project are the following ones: a) to point out unsolved conflicts among current standards at Regional, National and European level; b) to define common methods for designing strategic and specific solutions; c) to define a new development system (procedures and database) for action planning by testing it in a pilot case; d) to design guidelines in order to build a system for action plan applications supporting Regional, National and European Law reviews. In this paper the results coming out from a specific action of HUSH project carried on by the University of Florence are described. This specific action focuses to build up the geographical data platform for city action planning. To achieve this aim, a few of city Action Plan data platforms - available in Italy and in European countries-were analyzed and compared referring to address the requirements set out by National, Regional and European regulations.