The scope of this paper is to recognize the needs, restrictions and priorities in developing effort of a breaking through technology that will achieve to enable Cooperative Intelligent Transportation System (C-ITS) applications in existing road infrastructure, to make roads self-explanatory and forgiving for all road users and all vehicle generations with reduced maintenance cost, full recyclability and added value services, as well as supporting real-time predictive road maintenance functions. The enhanced broad functionality of the system on multiple levels imposes emerging needs and demands that will constitute the groundwork of the Use Cases for the implementation of the project, which are extracted through an iterative user-centered methodology approach and correspond to the target applications of the system. More particularly, the needs, views and priorities of all the relevant stakeholders have been captured through the outputs of 431 respondents participated from 10 countries in on-line and in-depth surveys. From the infrastructure point of view, the complementary investigation of relevant accident/incident and gaps/priorities was based on literature while the legal/operational limitations have been based on the study of relevant Directives and the view of experts. These sources provided important qualitative as well as quantitative outcomes, the aggregation of which led to the prioritisation of the target applications, two of which (last in ranking) are considered to be secondary in the sense that can be implemented with some flexibility.