Ballast is a major track component made from stone or rock, and SNCF Réseau uses enormous quantities of it. It takes about 2 tonnes of ballast per meter of line to ensure track stability, and for TGV lines that figure can go as high as 5 tonnes. In all, our network contains nearly 100 million tonnes of ballast—about 2,300 times the weight of the aircraft carrier Charles de Gaulle, or 10,000 times the weight of the Eiffel Tower!

When we renovate a railway line, we also have to replace the ballast on every kilometre of the works. Each year, we upgrade around 1,000 km of track, often using kilometre-long factory trains that consume some 2 million tonnes of ballast annually.

We’re working to shrink our environmental impact on many fronts—reducing the carbon footprint of our lines, reusing the materials we remove when we upgrade track, managing a rail recycling facility, slashing waste, and more. This is what inspired our effort to reclaim ballast—a product extracted from nature in a process that takes a heavy toll on biodiversity and water resources.

By 2025, we want to use 25% of recycled ballast in our rail network annually. That’s around 500,000 tonnes of ballast that won’t be extracted from mountains.

Until recently, we processed used ballast right on the line, but with that method, only 30% of the aggregate removed could in fact be re-used. The breakthrough we’ve made in the past 2 years is to process ballast on a platform near project sites. 
This recycled ballast performs at least as well as newly extracted product.

The key steps are:

• optimizing the washing process,
• creating a closed circuit to save water,
• monitoring particle size continuously for real-time production control,
• using a compact, mobile production unit.

Giving ballast a new lease of life requires 3 steps. Used ballast is collected, then screened in factory trains, washed and processed. Finally, it is sorted into different categories based on particle size and other characteristics.

Processed ballast can be:

• re-used in the rail system, to stabilize high-speed lines or France’s network of small rural lines
• re-purposed as aggregate to create roadways running parallel to railway lines
• sold to the construction industry

• at some sites, up to 72% of ballast has been returned to the track,
• a local industrial-scale environmental protection centre to reclaim co-products from the ballast treatment process has been created in Lille,
• our “100% local” strategy has reduced our greenhouse gas emissions and transport costs,
• it now costs less to process used ballast than to buy it new, thanks to our partnership with an SME,
• our facilities processed over 200,000 tonnes of ballast in 2022.

Every year, 2.6 million tonnes of material are removed from the railway network during track maintenance and upgrades. By working to collect, sort, re-use, repurpose and recycle ballast, we’re combining responsible corporate engagement with efficient business practices.