Roads are the main transport infrastructures of industrialised countries. Because of increasing traffic demands, roads generate more and more environmental impacts i.e. raw materials consumption, air pollution, noise. Most of industrialised countries have therefore introduced regulations imposing environmental evaluations before any new construction. Nevertheless, decisions concerning roads, and infrastructures constructions in general, are still mainly based on mechanical and economical criteria. Furthermore, technical choices (materials, geometry…) are delegated to competent technical services, in which tools based on mechanical analysis are operated. The Sustainable Development Team of Laboratoire Central des Ponts et Chaussées (LCPC) works to elaborate an environmental tool, which enables a global analysis of roads, including initial construction and maintenance, all along road service life. Besides, the aim of this work is precisely to provide available informations, allowing to bring environmental assessment with into initial decision making, without forgetting technical road parameters. The Life Cycle Analysis (LCA) standard framework (ISO 14040-43, 1997-2000), is well adapted to consider simultaneously technological and environmental parameters during the life cycle of manufactured products. This methodology has thus been applied on the environmental assessment of one material of a specific road case. However, this particular study showed the limit of the standard method in its application to road infrastructures (Ventura et al, 2003). Hence, a dedicated tool has been developed. The Elementary Road Modulus (ERM) uses an environmental model which derives from the LCA methodology. But on the contrary of the LCA functional unit concept, the ERM is elaborated to be fully modular in order to be easily adapted to various case studies. ERM modelling performs an inventory of input/output flows, focusing on pavement service life (construction and maintenance during exploitation). The next step of modelling is called Global Road Modulus (GRM). This second step consists in selecting existing (or developing new) impacts indicators, that takes territory aspects into account. The link between ERM and GRM modelling is based on an intermediate phase, which consists in calculating inputs/outputs inventory for subsystems involving territory dependent parameters. Among concerned subsystems, transport is highly linked to the road location. Hence, accounting for transport requires to work on a given case study belonging to French network in order to use realistic calculations distances as input parameters instead of fixed mean distances as input parameters like it was previously done for ERM modelling. The full inventory calculations model developed for every subsystem cannot be detailed in this paper and will be part of the phD report of T. Hoang that will be published in 2005. This paper only focuses on the model developed for transports inventory calculations. It carefully examines the choice of the case study to highlight distance influence. It first details Road Modulus tool principles and thus describes the case study particularities. Results such as energy and natural resources consumptions, as well as a selection of airborne emissions (CO2, NOx, and SO2), are then presented. (Author/publisher)
Samenvatting