Viaduc des Souverains: modernisation of a strategic 150-year-old bridge

Located in the 17th arrondissement of Paris, the Viaduc des Souverains is a key hub in the Île-de-France rail network. It spans 13 railway tracks, crossed every day by nearly 1,600 trains on lines J, L and RER C. This route also connects Normandy to the capital.

SNCF Réseau has begun the complete replacement of the 25 auxiliary decks. The aim is to guarantee the safety, reliability and performance of the network for decades to come, while limiting traffic disruptions.

A temporary auxiliary deck has been installed to keep trains running during the partial renewal of the structure between May and August – a first for ETF on this type of project.

An extraordinary construction site in the heart of a busy area

Bouygues Travaux Publics Régions France, the project manager, in partnership with ETF, is carrying out a complex construction project in the heart of a dense urban area. The configuration of the site, including a narrow tunnel only 15 metres wide, required rigorous logistics and millimetre precision at every stage.

The materials were transported by lorries and then installed using hydraulic jacks specially adapted to the site’s constraints. To meet these challenges, an innovative handling machine called Léonard was designed. This rail-mounted machine can move, lift, rotate and position elements weighing up to 50 tonnes, while reaching a height of 6 metres.

The presence of a dense network of underground electrical cables required constant vigilance: thanks to the rigour of the teams, no cables were damaged during the entire excavation work.

Strong measures to limit the impact

In order to minimise disruption to users, the most significant work is being carried out during specific periods: intensive operations

Since March, six of the nine planned weekends of work have already been completed: four weekends of preparation and two weekends of intensive work lasting 100 hours. The project will resume in August 2025 to finalise the work.

Innovation at the heart of the project

This project provided an opportunity to develop four major innovations designed to optimise deadlines, enhance safety and guarantee continuity of rail service:

• Léonard is an innovative railway lifting machine, specially designed for this project to replace the deck slabs from the RER C tunnel while maintaining surface traffic. Capable of pivoting, moving in all directions and lifting heavy loads, it adapts to the site’s demanding constraints thanks to hydraulic cylinders and a modular platform.
• New-generation temporary track supports have been deployed (innovative S4 supports). These ensure that adjacent rail traffic can continue during the excavation phases.
• Our catenary teams installed the new catenary gantry over five nights and a weekend in March.
• For the signalling gantry spanning the structure, SNCF opted for an ingenious solution consisting of reinforcing it at the base while the new foundation was being poured on the replaced deck, using a custom-designed beam and an extension of a secondary support on the downstream side. This choice made it possible to reinforce its stability while keeping the gantry active throughout the duration of the works.

280 experts mobilised

Thanks to meticulous planning and the unfailing commitment of the ETF teams (Ile-de-France agency, Caténaires, ETF Services) and its partners, the initial objectives have been achieved:

• Already 8 decks laid
• 6 tracks renewed
• 150 metres of catenary removed and replaced
• Zero accidents
• Deadlines met

This project embodies the major challenges of regenerating the historic rail network in a densely populated area: working on a heritage structureonial, tout en assurant la modernisation des infrastructures et la continuité du service ferroviaire.