Detailed Analysis and Standard Applications of Rail Types and Lengths

1. Types of Rails and Their Characteristics

【 Classification and Application of Rails 】

Rail types are generally classified by their mass per meter. In China, commonly used rail types include 75kg/m, 60kg/m, 50kg/m, 43kg/m, and 38kg/m. All these rails utilize an I-beam (or I-shaped) cross-section, which offers excellent bending resistance and features key components such as the rail head.

The 43G, 50G, and 60G rails are ingeniously composed of the web, head, and base. To ensure stability under various forces, their heights, as well as the areas and heights of the head and base, have been carefully designed. At the same time, the thickness of the web and base have been optimized to guarantee both strength and operational comfort.

In practice, 38kg/m rails are no longer produced, while 60kg/m and 50kg/m rails are mostly used for main lines. For station lines and dedicated tracks, 43kg/m rails are more commonly chosen. On heavy-haul railways or especially busy sections, 75kg/m rails are preferred. Furthermore, to meet the needs of special structures such as turnouts, large bridges, and seamless tracks, China has also introduced special-section rails (I-beam type, but asymmetrical to the central axis). Among them, low-profile special-section rails, known as AT rails, are widely used due to their unique advantages.

【 Bending Resistance and Design Considerations 】

The 43G, 50G, and 60G rails, composed of the web, head, and base, are specifically designed to withstand various forces, ensuring both strength and comfort.

 

2. Rail Lengths and Their Application

【 Standard Rails and Short Rails for Curves 】

In terms of length, the standard rail sizes in China are 12.5 meters and 25.0 meters. Extra heavy and heavy-duty tracks most commonly use 25.0-meter rails, while other tracks may use either 12.5 or 25.0 meters as needed. Notably, the "Interim Technical Requirements for 60kg/m Rails on 250km/h Passenger Dedicated Lines" stipulate that the standard rail length for 250km/h passenger lines (which may also serve freight transportation) is 100 meters.

For curved tracks, shorter rails known as curve short rails are used to better accommodate the curvature. There are various options, such as rails that are 40, 80, or 120mm shorter than the 12.5m standard, or 40, 80, or 160mm shorter than the 25.0m standard, among others.

Source: Internet