By the end of 2020, line B of the Rennes metro will be up and running between Saint-Jacques - Gaîté (in the northeast) and Cesson-Viasilva (in the southwest). Colas Rail is responsible for supplying and laying the slab track and walkways, along with the central guide rail and power rail. The studies, installation and trials of the air conditioning and ventilation systems in six of the underground stations took place between mid-2018 and mid-2019 … using augmented reality! BIM (Building Information Modeling) holograms were created. This innovative, original method enables teams to inspect the structure rapidly and interact with the model’s objects. For a standard station, the inspection time has been reduced ten-fold, falling from thirty hours to three hours. It should be noted that Aximum’s teams are working alongside Colas Rail on parts of the project, particularly the walkways.