The subject of this work is the risk assessment, concentrating on the constructions' workplaces of EU countries. Two significant methodologies (adapted from the scientific litterature), as well as a combined elaboration (joint analysis) of their results, are used for this purpose. The first one, is the Proportional Risk Assessment Technique (PRAT) (see [1], [2], [3]) and the second one, is the analysis of Time Series Processes (TSP) (see [4], [5]), concerning occupational accidents. In particular, real data of occupational accidents in Greece, Cyprus, France, Germany and Spain, are analyzed (PRAT-TSP joint analysis). These data have been collected from different official State sources or databases, throughout various time intervals, namely: (i) for Greece by "SEPE" (Labor Inspectorate, Ministry of Employment) regarding the years 2001-2011 (ii) for Cyprus by the "Department of Labor Inspection of Cyprus" (DLIC) concerning the years 2003-2011 and (iii) for the countries Greece, France, Germany and Spain from the "Eurostat" database covering the period 1996-2007. The relevant results, show that the estimated value for the magnitude of risk (R) in the worksites of the constructions sector (Constructions and Public Works) is, in some cases, greater than 200, that proves, according to the scientific litterature, the necessity of taking measures no later than one year, in order to downgrade the direct risk of arising fatal accidents.