The Charles de Gaulle car park is located under the esplanade of the same name, close to the train station and the historical city centre of Rennes. Programmed as part of the esplanade development operation, this car park has eliminated on-street parking and given the square back to pedestrians and travelling events.
The constraints involved over vehicle capacity, excess surface load, and access to the different facilities led to a singular project featuring three underground levels connected by circular ramps. The 800-vehicle capacity of the car park required the creation of several confines and the volume was therefore split into two parking compartments plus a central compartment solely dedicated to the vehicle circulation ramps. This set-up helps to optimise the number of parking spaces by grouping them at the periphery of each level, near the exits. The construction is almost entirely concrete: the slabs and wide-span beams (16m) were prefabricated and the confinement walls were cast on site. The two car ramps, one up, one down, are concrete slabs. To support each roadway, we increased the number of posts in order to reduce the stress. These low-diameter steel posts rise to the very top of the building. The fact that no car parking spaces could be placed in the ramp compartment meant that the different levels could all communicate, hence the cathedral effect with its forest of pillars and a central void soaring 11m high. This three-tier space highlights and displays the two vehicle circulation ramps and the footbridge that cuts between them. The lighting design reinforces the verticality of the posts and monumentalises the space via two cylinders of light in the middle of the ramps. A ring of dotted lights in the centre of the ramp is a reference to the circular motifs that structure the esplanade above.