Sharing information between stakeholders is a critical success factor for ecodesign projects. This sharing is based on indicators that can be interrelated, i.e., impacting each other. This article focuses on the perception of environmental performance indicators’ relationships during the design phase of projects. It uses a DEMATEL approach combined with a graph-database visualization linking environmental performance indicators. While the DEMATEL approach highlights the critical environmental indicators, the graph-based visualization maps the primary interrelations of these factors and defines the best scale to manage them. The novelty here lies in the complementary use of these two methods to facilitate environmental project monitoring. This research is applied to rail infrastructure projects. The main results insist on land optimization, landscape insertion, carbon footprint, economic benefits, and biodiversity measures as critical factors when designing these projects. The graph-based visualization maps the main oriented links between indicators, allowing managers to identify the gaps between the perceived knowledge and the ground truth, facilitating their project monitoring.