Given the demands of mass transit, upgrading the network to meet 21st-century requirements is vital. For SNCF Réseau, the challenge is to complete these upgrades while keeping as many trains as possible in service.

In 2026, SNCF Réseau will invest €2 billion in the Paris Region network, including over €800 million devoted exclusively to renovations. These upgrades include replacing tracks, switches, catenaries, switching stations and electrical systems—all critical to ensure a reliable network, keep trains running on time, and prepare for the introduction of next-generation rolling stock such as the RER NG.

Major projects in the Paris Region in 2026 include:  

• Replacing 40 switches in the underground sections of Paris-Nord and Paris-Lyon stations to enhance services on RER lines B and D. This work will take place from 25 July to 17 August.
• Renewing 150km of track and rails using a track renewal train – a specialized workhorse well-suited to the challenges of the Paris Region’s dense network.
• Connecting the new tracks and switches at Plaine Stade de France and Aulnay-sous-Bois stations to the traffic control unit in Saint-Denis, northern Paris. These new connections with existing infrastructure will allow greater operational flexibility during service disruptions.

When renewing infrastructure, SNCF Réseau does more than replace equipment. Each renovation is an opportunity to install innovations that make the network more climate-resilient. For example, new catenaries are designed to withstand extreme temperatures – from –10 °C to +60 °C – while also requiring less maintenance. Next-generation rails are engineered to absorb extreme heat, reducing the risk of deformation and ensuring consistent train speeds.