With infrastructure involved in as many as a third of all accidents, beyond extending education and enforcement policies, safe road engineering supported by sound research can help ensure consistently high levels of safety along Europe's road networks. When road safety policy is analyzed, three main areas of action can be defined corresponding to the three main actors involved in road safety: human, vehicle, and infrastructure. The three of them, usually called "the three safety pillars" are addressed in different ways. However, this range of domains must be dealt with subject to budget limitations. Consequently, cost efficiency of systems and measures needs to be a decisive factor for policy making. In this context, RANKERS (RANKing for European Road Safety) pursues the ambitious objective of developing scientifically-researched guidelines enabling optimal decision-making by road authorities in their efforts to promote safer roads and eradicate dangerous road sections. RANKERS is a research project co-funded by the European Commission designed to gain new knowledge by performing research and empirical studies of the road's interaction with the driver and his vehicle in order to identify optimal road recommendations and predict their impact on safety. The main output of the project includes an index used for assessing and monitoring road safety and a comprehensive catalogue of road infrastructure safety recommendations ranked according to their cost-effectiveness. RANKERS proposes to address traditional passive safety measures ("forgiving roads") together with a better understanding of the accident causation scenarios, leading to a significant mitigation of the risks posed by the road and its environment. The roads design should be directly focused to the concept of making "self-explaining roads", that is to say, advocating a traffic environment which elicits safe driving behaviour simply by its design so that the road user is neither confused nor invited to take risks.