Boulevard des Batignolles is deeply gutted in its part which overlooks the railway tracks of Saint-Lazare station.

In the open trench, a metal bridge was built; in its iron cage, the metro rolls in the open air.

On either side of this bridge, two others, similar, will be placed. They will carry below them, in a cement formwork, the various pipes which pass under the boulevard. At this time, what remains of the Batignolles tunnel can be demolished.

Boulevard des Batignolles will span the railway tracks on three metal bridges, without traffic being interrupted at any time during this important work, neither that of the Metro nor that on the surface.

During the construction of the central bridge, traffic was diverted to the shoulders. It will only be done via this bridge, as long as the construction of the other two lasts.

The demolition of the tunnels, it should be remembered, was undertaken in October 1921. The demolition of the vaults, up to Boulevard des Batignolles, over a length of 256 meters, lasted two years. It was necessary to build two immense retaining walls, lining the vaults with iron arches, in order to demolish them without interrupting traffic.