What is the primary purpose of EN 13231-5?

The primary purpose of EN 13231-5 is to define the technical procedures and quality criteria for the acceptance of rail reprofiling works. It ensures that the restored rail profile on plain line, switches, and crossings meets specified geometric tolerances and is free from surface defects, guaranteeing safety and performance.

Does EN 13231-5 specify how to reprofile a rail?

No, EN 13231-5 does not dictate the method of reprofiling (e.g., grinding vs. milling). Instead, it focuses on the final result. It specifies the required quality of the finished rail surface and profile, which must be achieved regardless of the technique used. The standard is about acceptance criteria, not the execution process.

What are the main parameters measured for acceptance under EN 13231-5?

The main parameters measured are the transverse profile (the cross-sectional shape of the rail head compared to a target profile), the longitudinal profile (the smoothness of the rail surface along its length, checked for different wavelengths), and the surface condition (checked for cracks, thermal damage, and metal flow).

Why are there special procedures for switches and crossings in the standard?

Switches and crossings have complex and continuously changing geometries, different material properties (like in manganese frogs), and critical functional interfaces. Special procedures are required to ensure the reprofiling correctly restores these intricate shapes and guarantees the safe and smooth passage of wheels, which is more challenging than on straight, uniform plain line track.

Who uses the EN 13231-5 standard?

The standard is used by railway infrastructure managers, who specify the required quality levels in their contracts, and by contractors who perform the rail reprofiling work. It serves as the contractual basis for verifying and accepting the quality of the finished work, ensuring all parties have a common understanding of the requirements.

European Rail: EN 13231-5 Defines Reprofiling Quality & Safety

December 15, 2024 2:02 am

Understanding EN 13231-5: A Technical Guide to Rail Reprofiling Acceptance

EN 13231-5 is a European Standard that specifies the technical requirements and procedures for the acceptance of rail reprofiling works on railway tracks. It covers plain line, switches, crossings, and expansion devices, ensuring that restored rail profiles meet precise quality and safety criteria for modern railway operations.

This standard is a critical component of the EN 13231 series, “Railway applications – Track – Acceptance of works,” which provides a comprehensive framework for verifying the quality of track construction and maintenance. Part 5 focuses specifically on the final state of the rail head after it has been machined by grinding or milling to remove defects and restore its designed shape.

The Scope and Objectives of EN 13231-5

The primary goal of EN 13231-5 is to provide a unified, measurable, and contractual basis for infrastructure managers and contractors. It establishes a common language and set of criteria to determine whether a reprofiling job is acceptable. The key objectives include:

Quality Assurance: To guarantee that the reprofiled rail surface is free from significant defects and adheres to the specified geometric tolerances.
Safety and Performance: To ensure the wheel-rail interface is optimized, which is crucial for vehicle stability, passenger comfort, and reducing the risk of derailment.
Asset Longevity: To effectively remove surface defects like Rolling Contact Fatigue (RCF), corrugations, and wear, thereby extending the service life of the rail.
Standardization: To create consistent acceptance procedures across different networks and contractors, facilitating interoperability and clear contractual obligations.

The standard applies to all reprofiling activities, whether conducted by rail grinding trains or specialized milling machines, on both conventional and high-speed lines.

Key Technical Procedures and Measurement Parameters

EN 13231-5 outlines a detailed set of measurements and inspections to be performed after the reprofiling work is complete. The acceptance is based on quantitative data rather than subjective assessment.

Transverse Profile

The transverse profile refers to the cross-sectional shape of the rail head. The goal of reprofiling is to restore this shape to a specific “target profile.”

Measurement: This is checked using calibrated profile gauges, optical measurement systems, or other approved devices.
Acceptance Criteria: The deviation between the measured profile and the target profile must be within specified tolerances, typically measured in fractions of a millimeter. The standard defines different tolerance classes (e.g., Class 1, Class 2) to suit various operational requirements, such as line speed and axle load.

Longitudinal Profile

The longitudinal profile measures the smoothness of the rail running surface along its length. It is critical for controlling noise, vibration, and dynamic forces on the track.

Measurement: Assessed using trolley-based measurement systems or integrated systems on grinding/milling machines that record the rail’s surface geometry.
Acceptance Criteria: The standard defines acceptable limits for wave-like defects (corrugations) across different wavelength bands (e.g., short, medium, and long waves). The criteria are typically expressed as a maximum peak-to-peak amplitude for each wavelength range. For example, short-wavelength defects can cause high-frequency noise, while long-wavelength defects impact ride comfort and vehicle dynamics.

Surface Condition and Visual Inspection

After geometric measurements, a thorough visual inspection is required to identify any remaining surface defects that could compromise the rail’s integrity.

Metal Flow (Lipping): Excessive metal flow at the gauge corner or field side must be removed, as it can hide underlying defects and alter wheel-rail contact.
Surface Cracks: The reprofiled surface must be free of visible cracks, particularly those associated with RCF.
Thermal Damage (Grinding Burns): The surface must be checked for signs of metallurgical damage caused by excessive heat during grinding, often visible as blue or dark discolorations. Such areas can be brittle and prone to premature failure.
Surface Finish: The texture and pattern of the grinding or milling marks are also evaluated to ensure they are within acceptable limits and do not create adverse contact conditions.

Acceptance Criteria Comparison Table

The following table summarizes the key parameters and general acceptance principles as defined in EN 13231-5. Note that specific tolerance values are determined by the contract and the chosen tolerance class.

Parameter	Area of Application	General Acceptance Principle	Measurement Method
Transverse Profile	Plain Line, Switches & Crossings	The measured rail head shape must conform to the target profile within a specified tolerance band (e.g., ±0.3 mm for a high-quality class).	Profile measurement gauge, optical/laser systems.
Longitudinal Profile (Short Waves)	Plain Line	Peak-to-peak amplitude of waves in the 10-30mm wavelength range must be below a defined threshold to control noise.	Recording measurement trolley, on-board systems.
Longitudinal Profile (Medium/Long Waves)	Plain Line	Peak-to-peak amplitude of waves in the 30-300mm+ wavelength range must be below a defined threshold to ensure ride comfort and limit dynamic forces.	Recording measurement trolley, on-board systems.
Surface Defects	All areas	No visible evidence of cracks, thermal damage (blueing), or significant surface imperfections.	Visual inspection, sometimes aided by dye penetrant or magnetic particle inspection if required.
Metal Flow / Lipping	Gauge Corner	Any overhang of displaced metal must be completely removed.	Visual and tactile inspection.

Special Considerations for Switches, Crossings, and Expansion Devices

Reprofiling in complex track sections like switches and crossings (S&C) is significantly more challenging than in plain line. EN 13231-5 provides specific guidance for these areas due to their intricate geometries and critical functions.

Complex Geometries: The standard requires careful attention to the transition zones between different components, such as between the switch blade and the stock rail, or at the crossing nose (frog). The transverse profile changes continuously in these areas.
Material Interfaces: Crossings are often made of high-manganese steel, which has different properties from standard carbon steel rails. The reprofiling process must be adapted to avoid damaging this material.
Functional Integrity: The primary objective in S&C is to ensure a smooth and safe transfer of the wheelset from one line to another. The reprofiling must maintain or restore the precise geometric relationships between all components to guarantee this functionality.
Measurement Points: Acceptance measurements must be taken at specific, critical locations defined in the work specifications to verify that the complex profiles are correct.

Conclusion: The Importance of Standardized Acceptance

EN 13231-5 serves as an indispensable tool for the modern railway industry. By providing clear, objective, and technically sound criteria for the acceptance of rail reprofiling, it bridges the gap between the infrastructure manager’s requirements and the contractor’s delivered work. Adherence to this standard ensures that maintenance investments result in a track that is not only free of defects but is also optimized for safety, performance, and a long service life. It is fundamental to maintaining the integrity and reliability of the entire railway network.