What is the primary purpose of EN 13232-2?

The primary purpose of EN 13232-2 is to specify the detailed requirements for the geometric design of railway switches and crossings. It establishes a common set of rules and parameters to ensure the safe, reliable, and interoperable passage of trains through complex track layouts like turnouts and diamond crossings.

Does EN 13232-2 specify which materials to use for switches and crossings?

No, EN 13232-2 focuses exclusively on geometric design. Material specifications, manufacturing requirements, and quality criteria for components like rails, bearers, and fastenings are covered in other parts of the EN 13232 standard series and other related standards.

How does EN 13232-2 relate to the maximum speed of a turnout?

The standard is directly related to speed. Key geometric parameters, such as the turnout radius and the switch entry angle, are the primary factors that determine the maximum permissible speed through the diverging route of a turnout. Larger radii and smaller angles allow for higher speeds by minimizing lateral acceleration and dynamic forces on the rolling stock.

Is compliance with EN 13232-2 mandatory?

As a European Standard (EN), its application can be voluntary unless it is cited in a contract or mandated by national or European regulations. However, for projects related to interoperability on the Trans-European Networks (TEN), compliance with relevant EN standards like this one is often a requirement specified by Technical Specifications for Interoperability (TSIs).

EN 13232-2: Europe’s Blueprint for Safe & Fast Rail Switches

December 15, 2024 2:02 am

Understanding EN 13232-2: Requirements for Geometric Design in Railway Switches and Crossings

EN 13232-2 is a fundamental European Standard within the railway sector that specifies the core requirements for the geometric design of switches and crossings. As a key part of the EN 13232 series, its primary function is to define the rules and parameters that ensure safe, reliable, and interoperable passage of rolling stock through turnouts, diamond crossings, and other complex track layouts.

The standard establishes a common technical language and a set of design principles for manufacturers, infrastructure managers, and engineers. By adhering to EN 13232-2, designers can guarantee that their switch and crossing units will function compatibly with a wide range of wheelsets and vehicle types operating on European railway networks, which is crucial for cross-border traffic.

Core Principles of Geometric Design in EN 13232-2

The entire standard is built upon the principle of safely guiding the wheelset from one track to another. This involves managing the complex interaction between the wheel flange and the rail. The key objectives of the geometric design as outlined in the standard are:

Defining a Continuous Running Edge: The standard details how to define the “fictitious running edge,” which is the theoretical line that the wheel’s flange root follows. This ensures a smooth path without abrupt changes in direction or support.
Controlling Wheel Transfer: It provides rules for managing the transfer of the wheel from a stock rail to a switch rail, and across the gap at the crossing nose (frog).
Preventing Derailment: All geometric parameters, especially flangeway gaps and check rail positions, are calculated to prevent flange climbing, incorrect routing, or dropping of the wheel into a gap.
Minimizing Wear and Dynamic Forces: A well-designed geometry reduces impact forces as wheels pass through crossings, leading to longer component life, reduced maintenance, and better ride comfort.

Key Geometric Parameters and Definitions

EN 13232-2 defines a comprehensive set of parameters that must be calculated and verified. These form the technical backbone of any switch or crossing design.

Turnout Radius

This is the radius of the curved path on the diverging track of a turnout. It is a primary factor in determining the maximum permissible speed through the diverging route. A larger radius allows for higher speeds, while a smaller, sharper radius is used in low-speed areas like yards and sidings.

Switch Entry Angle (α)

This angle is formed between the running edge of the stock rail and the switch rail at the point of the switch (the “toe”). A smaller angle provides a smoother transition and is essential for high-speed turnouts, whereas a larger angle is acceptable for low-speed applications.

Flangeway Gaps

These are precisely controlled gaps that allow the wheel flange to pass through the switch and crossing area. The standard specifies minimum and maximum values for the flangeway at various points to ensure the wheel is guided without being too constrained (risking seizure) or too loose (risking impact or misdirection).

Free Wheel Passage

This is a critical safety dimension at the crossing nose. It represents the minimum unobstructed gap through which the back of a wheel flange on one rail can pass while the other wheel is guided along its path. An incorrect free wheel passage can lead to a wheel striking the point of the crossing nose, causing severe damage or derailment.

Check Rails and Guard Rails

EN 13232-2 defines the geometric requirements for placing check rails opposite the crossing nose. The function of a check rail is to guide the corresponding wheel on the other rail, preventing its flange from taking the wrong path at the crossing. The distance between the check rail and the running rail (check gauge) is a critical safety parameter.

Types of Switches and Crossings Covered

The standard is applicable to a wide range of common trackwork designs, including:

Turnouts (Switches): The most common form, allowing a train to divert from a straight track to a branching track.
Diamond Crossings: Allowing two tracks to cross each other at an angle. These can be “fixed” (common) or “movable” (swing-nose) for higher speeds.
Single and Double Slips: A more complex arrangement that combines the function of a crossing with turnouts, allowing trains to switch between two parallel tracks in a compact space.
Scissors Crossovers: Two crossovers that overlap each other, often used at the entrance to major stations to provide flexible routing options.

Geometric Design Comparison: High-Speed vs. Low-Speed Applications

The application of EN 13232-2 principles varies significantly based on the intended operating speed of the track. The following table illustrates some key differences:

Parameter / Design Aspect	Low-Speed Application (e.g., Yard)	High-Speed Application (e.g., Mainline)
Turnout Radius	Small / Sharp (e.g., 190m – 500m)	Large / Gentle (e.g., 1200m – 7000m or more)
Switch Entry Angle	Relatively larger, allowing for a more compact design.	Very small (acute), ensuring a gradual change in direction to minimize lateral forces.
Crossing Type	Typically fixed (cast monobloc or fabricated) common crossing.	Often a movable (swing-nose) crossing to eliminate the gap and provide a continuous running surface.
Cant (Superelevation)	Generally not applied or minimal.	Often required through the diverging path to counteract centrifugal forces and improve comfort.
Design Complexity	Simpler geometry, focused on functionality and space-saving.	Highly complex geometry, optimized for minimizing dynamic forces and ensuring passenger comfort.

Conclusion: The Role of EN 13232-2 in Modern Railways

EN 13232-2 is more than just a document of rules; it is the cornerstone of safe and efficient switch and crossing design in Europe. It provides a standardized framework that promotes interoperability, ensures a baseline level of safety, and allows engineers to design trackwork that is appropriate for its intended use, from low-speed shunting yards to high-speed mainlines. Its focus on the precise geometric interaction between wheel and rail is critical for the performance, reliability, and longevity of the most mechanically complex components in the entire track infrastructure.