In winter, heavy snowfall can create drifts that cover railways. When a train passes at high speed, snowflakes swirl up and accumulate on its underbelly, where cold air solidifies the snow and transforms it into a heavy block of ice. When 2 trainsets pass each other, they create suction, and shards of ice fly off like projectiles.

This happens primarily on high-speed lines, where impacts can reach 600 km/h. Under severe conditions, a shard of ice can crack a window—and even damage critical components, such as sensors under the train that relay data to the driver’s cab.

Every year, we draft a Winter Preparedness Plan, with a range of measures to prevent and repair ice damage:

• The fairings (front portions) and shells of our TGVs protect sensitive components such as sensors and brake circuits from the cold.
• We apply de-icing fluid to the underside of our trainsets to prevent snow from sticking.
• We set up a nationwide network of emergency response teams, plus repair teams at our specially equipped maintenance centres.

In addition, our TGVs feature double-paned windows 5 cm thick, with a plastic film to create the best possible seal on the inside. If a window cracks, we use the resin injection method to repair it.

To reduce the hazards of flying shards of ice, a train may slow down along all or part of its route, which can increase running time and cause delays.

For example, the normal travel time for a TGV between Grenoble and Paris-Lyon station is 3h03. But that can change if it’s forced to slow down on part of the high-speed line:

• if the TGV runs at 220 km/h instead of 300 km/h, running time is 15 minutes longer
• if it runs at 160 km/h instead of 300 km/h, running time is 35 minutes longer

When blocks of ice remain stuck to the underside of coaches over several days, the risk of flying ice persists, and we continue to run at lower speeds.