Rail Weight Per Metre

The rail weight per metre is the single most important identifier for a rail profile, serving as a primary indicator of its strength, load-bearing capacity, and intended application. This metric, expressed in kilograms per metre (kg/m), directly correlates with the rail’s dimensional properties, such as height, head width, and base width. A higher rail weight per metre generally signifies a more robust rail designed for heavier loads and higher speeds, as seen in heavy-haul freight and high-speed passenger lines. This technical guide explores the specifications of common rail profiles categorized by their weight and details the corresponding fastening systems and clips required to support them.

Heavy-Duty Rail Specifications (Above 55 kg/m) and Rail Weight Per Metre

Rails with a rail weight per metre above 55 kg/m are engineered for the most demanding railway applications. This category includes the profiles used for mainline heavy-haul freight, high-speed passenger routes, and mixed-traffic corridors with high tonnage. The increased mass comes from larger cross-sectional dimensions, providing the necessary stiffness and strength to handle extreme dynamic forces safely and durably. The most common profiles in this category are the 60E1 (UIC60) and the 54E1 (UIC54).

Common Heavy-Duty Rail Profiles

The 60E1 profile is a global benchmark for modern, high-performance railways. Its rail weight per metre of approximately 60 kg makes it suitable for both high-speed lines and routes with significant freight traffic.

Material Grades and Properties

Heavier rails are manufactured from advanced steel grades to maximize their service life. The steel must possess high hardness to resist wear and exceptional internal cleanliness to prevent fatigue failures.

• R260 Grade: A standard-strength carbon steel with a tensile strength of at least 880 MPa. It is used on mainline tracks with moderate traffic.
• R350HT Grade: A premium heat-treated grade with a tensile strength exceeding 1175 MPa. This is the standard for high-speed and heavy-haul applications, offering excellent wear resistance and fatigue strength.
• Alloyed Grades: For the most extreme wear conditions, such as sharp curves on heavy-haul lines, alloyed steel grades containing elements like chromium (e.g., R320Cr) are used to further increase hardness and durability.

Fastening Systems and Clips for Heavy Rails

The fastening systems for rails with a high rail weight per metre must provide exceptional clamping force and longitudinal restraint. The clips are designed to secure the rail against immense forces generated by heavy trains and thermal expansion.

• Elastic Clips for Heavy Haul: Systems like the Pandrol e-Clip or Vossloh W-series are engineered to provide a very high clamping force, often exceeding 18 kN per clip. These clips are made from high-quality spring steel and are used with robust cast-iron shoulders anchored into concrete sleepers.
• High-Speed Fastenings: While still providing high clamping force, these systems are also designed for vibration attenuation. They incorporate soft, elastic rail pads to reduce noise and improve passenger comfort. The dynamic stiffness of the system is a critical, specified parameter.

Medium-Weight Rail Specifications (40-55 kg/m) and Rail Weight Per Metre

Rails in the medium-weight category are versatile profiles used for a wide range of applications, including regional lines, light rail transit (LRT), metro systems, and industrial tracks. The rail weight per metre in this range offers a good balance between load-bearing capacity and economic efficiency. Common profiles include the 49E1 (S49) and various national standards within this weight class.

Common Medium-Weight Rail Profiles

The 49E1, with a rail weight per metre of approximately 49 kg, is a widely used profile for secondary lines and urban rail systems across Europe and other regions.

Material Grades and Properties

The steel grades for medium-weight rails are typically standard-strength carbon steels, as the operational demands are less severe than on primary mainlines.

• R200 & R220 Grades: These are the most common grades, with tensile strengths of 700 MPa and 780 MPa, respectively. They provide good toughness and adequate wear resistance for moderate axle loads and traffic frequencies.
• Harder Grades for Urban Curves: In urban rail systems, especially in tight curves, harder grades like R260 or even heat-treated rails may be used to combat high rates of side wear and extend rail life.

Fastening Systems and Clips for Medium Rails

Fastening systems for medium-weight rails vary widely depending on the application.

• Direct Fixation: For urban slab track (LRT/metro), the rails are often secured using highly elastic fastening systems anchored directly into the concrete. These systems are designed for maximum vibration and noise reduction, featuring soft rail pads and resilient components. The clamping force is moderate (~10 kN) to allow the system to remain flexible.
• Sleeper-Based Systems: On regional and industrial lines with concrete or timber sleepers, a variety of clip systems are used. These can range from simple rigid clips bolted to a baseplate to more modern elastic clips that reduce maintenance needs. The primary goal is to hold the track gauge securely and prevent rail movement.

Light-Duty Rail Specifications (Below 40 kg/m)

Rails with a low rail weight per metre (under 40 kg/m) are used for light-duty applications where loads and speeds are minimal. This includes mine railways, temporary construction tracks, amusement park rides, and light industrial sidings. The American ASCE series of rails are common in this category.

Common Light-Duty Rail Profiles

These profiles are designed for economy and ease of handling. The designations often refer to the weight in pounds per yard.

Material Properties and Fastening Systems

Light-duty rails are made from standard, low-cost carbon steel. The fastening systems are typically simple and purely functional.

• Rail Spikes: For tracks laid on timber sleepers, traditional rail spikes are the most common fastening method. They are driven into the wood to hold the rail in place.
• Bolted Clips and Hook Bolts: For rails laid on concrete or steel structures, simple bolted clips or J-shaped hook bolts are often used. These provide basic clamping force and are easy to install and adjust. The performance requirements are low, as the forces involved are minimal. These systems prioritize cost-effectiveness over the high performance seen in mainline railway applications.