Life Cycle Analysis and Decision Aiding: An example for roads evaluation.

Road infrastructure building in civil engineering implies high initial cost investments whereas environmental effects have extensively been considered: i) before the construction regarding infrastructure localisation inside a given territory ii) only taking into account possible impacts on territory during infrastructure exploitation. A more global approach of environmental impacts through the whole infrastructure life cycle would therefore be of great interest to give more complete evaluation for decision aiding. Among possible methods available for such an approach, Life Cycle Analysis (LCA) is a methodology considering together resources extraction and materials manufacturing, construction steps, exploitation and maintenance during life time of a manufactured product. Although LCA can be applied to road materials evaluation, the methodology has to be adapted for the full infrastructure because of different road layers service life cycles. Anyway, economic evaluation remains a valuable mean for choosing between several road variants. Economical aspects coupled with an LCA environmental evaluation can threfore provide a relevant multicriteria approach to the decision-maker. However, before such methodology application, the use and place of LCA in a decision process should be defined without ambiguity. Hence, this paper deals with similarities and differencies between LCA and what we call a Decision Aiding Process. Both processes are compared and analysed to determine how LCA can be used for taking decision