Why do we need an underground when we are building a tramway?

Trams generally run on the surface. However, the natural slope between the plateau and the Seine valley is too steep to allow the tramway to circulate in optimal conditions of comfort and safety. The construction of an underground section from the RN7 makes it possible to soften this gradient and allow the tramway to run on a more gradual slope, while maintaining a direct and fast route to Juvisy station.

Beyond this topographical constraint, the choice of an underpass also responds to major urban challenges. This solution makes it possible to limit the impact on a particularly dense urban fabric and to reduce as much as possible the demolitions that would have been necessary in the context of an entirely above-ground development.

It also helps to preserve the landscape and heritage qualities of the area. The insertion of the tramway underground limits the interventions within the park of the Juvisy Town Hall, preserves its historical perspectives and makes it possible to highlight remarkable elements such as the Ducastel building and the Camille Flammarion Observatory, classified as a historical monument.

The underground section will be approximately 900 metres long. It will include a fully covered section of about 600 metres, consisting of the tunnel, the cut-and-cover and the underground Observatory station, as well as a section of about 300 metres made in an open trench, where the tramway will gradually descend under the RN7 before emerging in the lower part of the Parc de la Mairie.

The use of an underground section is therefore the most suitable solution to meet the topographical, urban, heritage and environmental constraints of the territory, while guaranteeing the expected performance of the future tram line.