In order to cope with their growing traffic problems, cities throughout the world deploy Intelligent Transport System (ITS) applications in various fields of urban networks. The decision making process for the installation of ITS is a dialogue between the political instance of the municipalities and the planners. The strategic concept and the detailed planning are undertaken by transportation experts in the respective planning authorities and is based on a vast variety of measurements and evaluations (Reed et al., 1993). The decision for funding the systems however is taken on a political level and is based on the consideration of expected benefits, economic aspects but also public debates and controversies. It is obvious that this dialogue within an inhomogeneous group of stakeholders needs a common basis for the consideration of benefits of ITS as a counterpart to the often obvious costs.In order to deliver this common basis of discussion, a transparent methodology to calculate and present the benefits of ITS has to be elaborated.This methodology should support the decision making process in several aspects:? to identify best practice applications already operational in similar cases in other cities;? to decide on the installation of the system on a technical and a political level;* Technische Universität München† IUAV University of Venice‡ Imperial College London§ Technion, Israel Institute of Technology2. to monitor the performance of the deployed application over a longer period of time;to weigh the investment and operational cost compared to thebenefits of the system. Several solutions to this problem were proposed within the EU FP7 project CONDUITS (2009 - 2011). They included the elaboration of a set of Key Performance Indicators (KPI) targeting different categories of ITS and providing a single, measurable value for their benefit. The following paper gives an overview of the definition process for the KPI, explains their function and gives an example for the calculation of the KPI based on real-life data provided by the city of Rome
