Track ballast

Track ballast forms the bed upon which railroad ties (US) or railway sleepers (UK) are laid. It is packed between, below, and around the ties. It is used to facilitate drainage of water, bear the load from the railroad track, and to keep down vegetation that might interfere with the track structure. The ballast also holds the track in place as the trains roll over it. It typically consists of crushed stone, although other, less suitable materials have been used such as burnt clay. The term "ballast" comes from a nautical term for the stones used to stabilize a ship.

Composition

Track ballast is typically made from crushed stone, the sharp edges and size variety of the stones help them lock together to provide a stable foundation. Materials used can vary regionally, and can include limestone, granite, basalt, and slag. The choice of material depends on the availability of resources, the load that the track must bear, and the weather conditions it will be exposed to.

Functions

The primary functions of track ballast include providing stability to the tracks, ensuring proper drainage, and maintaining the correct track alignment. The ballast achieves this by being angular and interlocking, which helps it stay compact and resist movement. Proper drainage is crucial to prevent water from pooling around the tracks, which can cause the wooden ties to rot and the track to become unstable.

Maintenance

Over time, the ballast is subjected to the wear and tear of continuous train traffic, which can lead to a phenomenon known as "ballast fouling." This occurs when the ballast becomes contaminated with broken down pieces of the ties, soil, and other debris, reducing its drainage capability and stability. Maintenance of the track ballast involves periodic cleaning and adding new ballast. The process of cleaning the ballast is known as "ballasting," which involves removing the old ballast, screening it to remove any debris, and replacing it with fresh material.

Environmental Considerations

The extraction and use of track ballast can have environmental impacts, including habitat destruction and the use of non-renewable resources. Efforts are being made to use recycled materials and to find more sustainable sources of ballast. Additionally, proper management of ballast can minimize its environmental footprint, such as using ballast that is locally sourced to reduce transportation emissions.

See Also

• Railroad tie
• Railway sleeper
• Railroad track
• Limestone
• Granite
• Basalt
• Slag

References

This railway related article is a stub.