The paper presents the findings of a research project aiming to quantify and subsequently classify several infrastructure-related road safety measures, based on the international experience attained through extensive and selected literature review and additionally on a full consultation process including questionnaire surveys addressed to experts and relevant workshops. Initially, a review of selected research reports was carried out and an exhaustive list of road safety infrastructure investments covering all types of infrastructure was compiled. Individual investments were classified according to the infrastructure investment area and the type of investment and were thereafter analysed on the basis of key safety components. These investments were subsequently ranked in relation to their safety effects and implementation costs and on the basis of this ranking, a set of five most promising investments was selected for an in-depth analysis. The results suggest that the overall cost effectiveness of a road safety infrastructure investment is not always in direct correlation with the safety effect and is recommended that cost–benefit ratios and safety effects are always examined in conjunction with each other in order to identify the optimum solution for a specific road safety problem in specific conditions and with specific objectives.