Daniel Buren’s project is based on the regular installation, at each stop on the West-East line, of line 1 (except at Porte Jeune) of two arches that mark the stations and create a feeling of continuity along the tramway route. The arches symbolise an entrance door and an exit door whose spacing is close to the length of the tramway trains; they span the platform. The arches have a rectangular cross-section. On three of the four sides of the arches, different colours have been used. Each station has different colours, creating a new world at each stop. On the outer curve, five black and white stripes of equal width extend in a straight line from the ground on either side of the arch, giving the appearance of stripes. Daniel Buren is known to have made the columns of the courtyard of the Royal Palace or the bridge arch of the Salves in Bilbao.