High-Speed Rail Standards

This technical guide outlines the stringent requirements for rails and fastening systems used in high-speed rail standards applications. The focus is on the specific material properties, dimensional controls, and performance criteria mandated by key European and international standards to ensure safety and reliability at speeds exceeding 250 km/h.

Table of Contents

High-Speed Rail Profile Specifications

High-speed rail standards (HSR) demands exceptionally high-quality rails to manage extreme dynamic forces, ensure ride comfort, and minimize wear. The primary standard governing these rails is the EN 13674 series, with specific grades and profiles selected for their superior performance characteristics.

EN 13674-1: Advanced Steel Grades for HSR

For high-speed applications, only the most robust, heat-treated steel grades are suitable. These grades are designed to offer exceptional hardness, wear resistance, and fatigue strength to withstand the millions of high-velocity load cycles.

Grade	Hardness (HBW)	Tensile Strength (Rm) MPa	Key Characteristics and HSR Application
R350HT	350 – 390	≥ 1175	(Heat Treated) The standard choice for many high-speed lines. It provides an excellent balance of wear resistance and ductility, suitable for tangent tracks and large-radius curves.
R350LHT	350 – 390	≥ 1175	(Low-Alloy, Heat Treated) A premium grade with a refined microstructure for enhanced fatigue resistance and weldability. Often specified for the most demanding HSR routes.
R400HT	≥ 390	≥ 1280	(High-Hardness, Heat Treated) A super-premium grade developed for tracks with extreme wear conditions, such as sharp curves or sections with heavy acceleration and braking.

These HSR grades undergo rigorous non-destructive testing, including enhanced ultrasonic inspections, to ensure they are free from internal defects that could lead to catastrophic failure under high-speed operation. Purity is paramount, with strict limits on elements like phosphorus (P), sulfur (S), and hydrogen (H).

Common High-Speed Rail Profiles and Dimensions

The 60E1 (UIC60) profile is the most widely adopted standard for high-speed rail in Europe and many other regions. Its robust design provides the necessary stability and strength. A newer profile, the 60E2, offers an optimized head design for improved wheel-rail contact and reduced wear.

Table of Nominal Dimensions for 60E1 and 60E2 Profiles

Parameter	60E1 Dimension (mm)	60E2 Dimension (mm)	Description
Height	172.0	172.0	Overall vertical height, providing bending stiffness.
Head Width	72.0	75.0	The width of the running surface. The wider head of 60E2 improves load distribution.
Base Width	150.0	150.0	The width of the rail foot, ensuring stability within the fastening system.
Web Thickness	16.5	16.5	Thickness of the vertical section connecting the head and foot.
Mass per Meter	60.21 kg/m	~60.34 kg/m	Nominal weight of the rail.
Moment of Inertia (Ix)	3055 cm⁴	~3100 cm⁴	Resistance to vertical bending, critical for maintaining track geometry under load.
Section Modulus (Head)	335 cm³	~353 cm³	A measure of the rail head’s strength against bending stress.

Dimensional Tolerances for High-Speed Rail

To ensure a smooth ride and minimize dynamic forces, HSR rails must be manufactured to extremely tight tolerances, significantly stricter than for conventional tracks.

Tolerance Parameter	Typical HSR Requirement	Consequence of Deviation
Straightness	< 0.3 mm over 1.5 m	Prevents high-frequency vibrations and ensures passenger comfort.
Height	± 0.4 mm	Maintains consistent running surface height, crucial for vehicle stability.
Head Width	± 0.5 mm	Ensures predictable wheel-rail contact mechanics.

Rail Clips and Fastening Systems for High-Speed Lines

Fastening systems for HSR are highly engineered components governed by standards like EN 13481. They must secure the rail against immense forces while also providing necessary elasticity and vibration isolation.

EN 13481: Performance Requirements for HSR Fastenings

The standard defines specific categories for fastening systems. For high-speed lines (speeds > 250 km/h), only systems meeting the most stringent performance criteria are used. These systems are typically installed on concrete sleepers or slab tracks.

Critical Functions of HSR Rail Clips

Rail clips for high-speed applications must deliver consistent performance under extreme conditions. Their design is a balance of stiffness and elasticity.

High Clamping Force: To prevent any micro-movements of the rail, HSR clips provide a very high clamping force, typically between 18 kN and 25 kN per clip. This robust force is essential to resist the powerful longitudinal waves generated by passing trains.
High Fatigue Resistance: HSR clips are subjected to intense, high-frequency loading. Standards require them to be tested for a very high number of load cycles (often exceeding 5 million) without any loss of performance or material degradation.
Controlled Stiffness: While strong, the fastening system must have a defined elasticity (stiffness) to help attenuate vibrations and manage dynamic wheel-rail forces, reducing noise and protecting track components.
Fail-Safe Design: The clip and its associated components are designed so that even if a component fails, the system maintains a degree of rail restraint, preventing immediate track gauge failure.

Key Performance Parameters for HSR Fastening Systems

Parameter	Typical HSR Requirement	Rationale and Importance in High-Speed Applications
Clamping Force	> 18 kN per clip	Resists powerful longitudinal forces from train passage, preventing rail creep and ensuring track stability. The force must remain consistent over decades of service.
Longitudinal Restraint	> 9 kN (for slab track > 11 kN)	Measures the system’s total resistance to rail slippage. A high value is critical to maintain the integrity of continuous welded rail (CWR) and prevent stress build-up.
Dynamic Stiffness (kdyn)	20 – 60 MN/m	This specifies the system’s elasticity under load. A lower value provides better vibration damping, crucial for passenger comfort and for tracks in urban or environmentally sensitive areas.
Attenuation of Impact Loads	> 25%	The ability of the rail pad and fastening to absorb shock. This protects the sleeper or slab from impact damage and reduces rolling noise.
Electrical Resistance	> 10 kΩ	High electrical insulation is mandatory to ensure the reliability of advanced signaling and train control systems (e.g., ETCS) by preventing signal interference.

Fastening Systems for HSR on Slab Track (EN 13481-5)

Slab track is the preferred foundation for many new HSR lines due to its stability and low maintenance needs. The fastening systems used here are even more advanced.

A typical HSR slab track fastening system (e.g., Vossloh 300-1 or Pandrol Fastclip FCA) includes:

Anchor Studs: Securely cast into the concrete slab.
Iron Baseplate: Provides a stable, adjustable platform for the rail.
High-Elasticity Rail Pad: A thick pad placed under the rail, specifically designed for high-frequency vibration damping.
Elastic Clips: Provide the high clamping force.
Angled Guide Plates: Precisely hold the rail to maintain gauge and resist lateral forces.
Adjustment System: Allows for fine-tuning of the rail’s vertical and lateral position to achieve the sub-millimeter geometric accuracy required for HSR.

These systems are designed as a complete unit to provide a specific dynamic response, forming a crucial link between the ultra-smooth rail and the rigid concrete foundation.