Grand Paris Express – Line 17 lot 2 :NGE and Cimolai Cross Europe’s Busiest Motorway
NGE (as lead contractor) and its partner Cimolai have reached a major milestone on Lot 2 of Line 17 of the Grand Paris Express, overseen by the Société des grands projets. During overnight operations, the joint venture installed the 200-metre viaduct for the future metro above the A1 and A3 motorways near Gonesse. Carried out during full motorway closures, the complex operation was successfully completed over the nights of 14, 15, 19, and 20 May 2025.
• France’s fourth-largest construction group, alongside its partner Cimolai, is delivering the elevated section of Lot 2 of Line 17
• The viaduct for the future metro now spans the 14 lanes of the A1/A3 motorways, following four nights of works
Highly technical and meticulously planned, the operation required a complete closure of the A1 and A3 motorways to ensure safe execution of the works. The viaduct structure was first assembled on a dedicated platform in Gonesse, before being moved into its final position using a launching method over four consecutive nights of traffic interruption.
The structure rests on six piers founded on piles, five of which are located on or adjacent to the motorway lanes.
This motorway crossing follows a series of major technical operations undertaken by NGE and Cimolai on Lot 2 of Line 17. Over the Easter weekend, another key milestone was achieved with the installation of three sections of the future metro viaduct, two of which span the RER B railway line. This operation, also carried out during a temporary suspension of SNCF rail traffic, was completed successfully and on schedule.