The objective of the research project is the investigation of effects to traffic safety, that are related to the age of heavy vehicles. Analytically, the following will be examined (a) the characteristics of heavy vehicles that deteriorate over time and make these vehicles prone to traffic accidents, (b) the influence of the age of heavy  vehicles in Greece and worldwide, (c) the condition of heavy vehicles in Greece and (d) the impacts of the age of heavy vehicles to traffic and the infrastructure.