This article discusses the potential of Life Cycle Assessment (LCA) as a support tool for decision-making in transportation planning. After summarizing the LCA method, it applies it to a bi-articulated Bus Rapid Transit system built around Fort de France, in Martinique, and a standard diesel bus rolling stock alternative. The system boundaries include operation, and the vehicle and infrastructure components. This case study forms the basis for discussions over the inclusion of LCA in project processes, the issues and impediments, and its incorporation into mandatory Cost- Benefit Analysis in France. The results show the project’s contributions to environmental impacts, captured via a set of 13 indicators. Bus fuel has a low impact on some indicators like solid waste or aquatic toxicities but a substantial impact (35 to 57%) on acidification, eutrophication, and climate change, demonstrating the importance of considering the entire system. With regard to infrastructure, hubs account for 25% of impact, while lighting can be substantial (up to 20%). Bi-articulated buses are a better option than standard diesel buses on most indicators under the assumptions of this study. However, modal environmental performances are highly context- sensitive. The impacts are normalized against those of the average passenger car, and compared with those of high-occupancy car modes. LCA could be used at every stage of project or policy design, with varying precision. However, its implementation is restricted by several factors, notably understanding and adoption by decision-makers, which are affected by issues such as results interpretation, extra workload and lack of dedicated tools.