In order to explore the long time influence on transportation planning, this article dissects the decision-making process of a by-pass project in Marseille, over 80 years. The methodology based on a long-term analysis allows to reconstruct the project story-line and to reveal a double dynamic of flexibility and irreversibility. Our analysis tends to show that we can go beyond the simple comprehension of blockings or progress in time-life project by a succession of conflicts or consensus between the stakeholders. By introducing a interpretation based on several temporalities, reversible and irreversible logics appears in the decision-making process and explain the persistence of a project out of alignment with current needs.
