Conclusion
Railroads - Components, construction and maintenance

The railroad, whose principle has remained unchanged for two centuries, has benefited, as has the entire railway system, from the development of a number of different applications: metallurgy for the rails, and civil engineering for track laying and bedding. Technological advances have increased performance in terms of rolling loads and speeds, while reducing maintenance costs and environmental impact. All track components contribute to the safety and reliability of rail traffic, at the highest level of land transport.