Today, the French rail network has some 5,700 km of disused line, most of it single-track. The FLEXY system aims to revitalize these small lines by offering a decarbonized, shared alternative to privately owned cars, especially in rural and suburban communities. This new mobility solution is designed for 30-km segments of line with at least 5 stations and potential ridership averaging 300-500 passengers a day.

The FLEXY system is being developed by a 4-member industrial consortium—SNCF, Michelin, Milla Group and the Railenium research institute—with support from France’s Brittany and Burgundy-Franche-Comté regions. Slated to enter commercial service by 2028, FLEXY has 4 components:

• Carflex, a hybrid road-rail electric shuttle
• streamlined infrastructure and maintenance
• specially-designed operating and control systems
• special regulations

The biggest innovation is that Carflex can run on both rail and road thanks to dual-purpose wheels, specially designed in partnership with Michelin. “With these wheels, we can deliver road service to communities near the tracks, travel through level crossings that have been converted into road intersections, and boost service on single-track lines by creating passing zones,” says Nathalie Peignet, FLEXY Project Leader, within the SNCF Tech4Mobility programme².

Carflex is accessible for people with limited mobility, and can contain up to 12 seats. But the modular interior can also be reconfigured to carry bicycles and micro-freight.

FLEXY’s infrastructure includes 3 types of smart, cost-saving platform. Transition platforms let the shuttle shift from road to rail, and vice versa. Intersection platforms allow Carflex to switch to road mode in places where old level crossings have become crossroads. And passing platforms boost service frequency on single-track lines by letting 2 shuttles pass each other.

Infrastructure maintenance costs are significantly lower for FLEXY lines, which have no level crossings or switches. Stations and light passenger platforms are the only equipment they need.

The FLEXY project includes a digitalized control system to manage the biggest railway risks, such as rear-end collisions, head-on collisions, and obstacles. At transition platforms, the shuttle’s wheels will be rerailed automatically to ensure safe operation and keep Carflex moving at rated speed as it shifts back onto the rail line.

The Carflex shuttle is designed to run at a minimum speed of 70 km/h by rail and 80 km/h by road—subject to local speed limits, of course. This level of performance will help keep the FLEXY system competitive with coaches and privately owned cars. In addition, rail lines are straighter and more direct than roads, and trains are unencumbered by the restrictions of road traffic.

As a hybrid, the FLEXY project must meet the requirements for both road and rail, and it needs a special set of regulations to run on the rail network. We’re now working on this in talks with the French Railway Safety Authority (EPSF) and the STRMTG, France’s national safety agency for ropeways and guided transport.

Carflex will run on dedicated lines that won’t be shared by any other type of railway rolling stock, and it will be monitored by driver-assistance systems when it passes other shuttles and travels through road-rail intersections. We plan to hold a system safety demonstration for French regulatory authorities in 2028 as part of the certification process.

In 2023, the SNCF Tech4Mobility team ran trials on a closed segment of rail line between Rosporden and Concarneau in south-western Brittany. They used a testbed vehicle called a mule³ to assess the vehicle’s ability to enter the system’s road-rail transition platforms. Also present were representatives of the Centre for Rolling Stock Engineering (CIM), SFERIS (an SNCF Réseau subsidiary), the French Railway Test Agency (AEF), and FLEXY project partners Milla Group, Michelin and Railenium.

Another closed rail segment, this time between Autun and Etang-sur-Arroux in Burgundy-Franche-Comté, will host validation trials of the FLEXY system starting at the end of 2026.