7. Conclusion

The wheel-rail bearing, the foundation of the railway system, is involved in all its components: rolling stock, infrastructure, energy required for train movement, traffic, operation and safety. Although based on proven technology, its components - in terms of geometry, materials and mechanical architecture - are constantly evolving. The wheel-rail contact allows for an increase in transported loads. With precise knowledge of the force compatible with contact friction, it is possible to use the available grip at its limits. The speed of traffic also depends on this; recent experiments at speeds of over 570 km/h have shown that usable grip is significant and allows traction force to be applied.

The development of guided rolling on tires has enabled a significant increase in transport capacity in urban environments without compromising fuel efficiency.