UITP-Aligned Urban Rail Standard | Cran Rail Clips Manufacturer Suzhou Xingrail

This technical guide covers the specifications for rails and fastening systems commonly used in metro and light rail transit (LRT) systems, aligning with the principles and best practices promoted by the UITP (International Association of Public Transport). The focus is on the unique requirements of urban rail, including specialized rail profiles for embedded track, and fastening systems designed for vibration damping and noise reduction.

Table of Contents

Urban Rail Profiles: Grooved and Vignole Rails

Urban rail systems use a combination of conventional vignole (flat-bottom) rails and specialized grooved rails, depending on the track’s location (e.g., in a tunnel, on a dedicated right-of-way, or embedded in a street).

Grooved Rails for Embedded and Street-Running Track

Grooved rails are essential for light rail and tramway systems where tracks are embedded in pavement, allowing road vehicles and pedestrians to cross safely. The profile features a groove that provides a channel for the wheel flange. The EN 14811 standard is the primary European specification for these rails.

Common Grooved Rail Profiles and Steel Grades

Profile	Mass per Meter	Key Application	Common Steel Grades (EN 14811)
59R2 (Ri59N)	~59 kg/m	A widely used profile for standard street-running applications with moderate traffic. Provides a good balance of durability and installation ease.	R200, R260, R290GHT
60R2 (Ri60N)	~60 kg/m	A heavier, more robust version of the Ri59, suitable for lines with higher traffic density, heavier light rail vehicles (LRVs), and mixed traffic.	R200, R260, R290GHT, R340GHT
53R1 (Ph37)	~53 kg/m	A lighter profile often used in depot areas, less-trafficked lines, or for track renewals where interfacing with older infrastructure is required.	R200
73R1	~73 kg/m	An extra-heavy-duty profile designed for the most demanding urban environments, such as tight curves in city centers or sections shared with buses.	R260, R290GHT, R340GHT

Steel Grades for Grooved Rails:

R200: Standard carbon steel for low-wear environments.
R260: A harder grade for increased wear resistance on straight sections and wide curves.
R290GHT: A heat-treated grade providing superior hardness and wear resistance, ideal for curves and high-traffic areas.
R340GHT: A premium, micro-alloyed heat-treated grade for extreme wear conditions, significantly extending rail life in critical locations.

Table of Nominal Dimensions for 60R2 (Ri60N) Profile

Parameter	Dimension (mm)	Description
Height	180.0	Overall vertical dimension.
Head Width	86.0	Total width across the running head and guard lip.
Base Width	180.0	Width of the rail foot, providing stability in the embedding material.
Groove Width	42.0	The width of the channel for the wheel flange.
Groove Depth	45.0	The depth of the flange-way.
Mass per Meter	60.99 kg/m	Nominal weight of the rail.
Moment of Inertia (Ix)	2005 cm⁴	Resistance to vertical bending.

Vignole Rails for Tunnels and Dedicated Rights-of-Way

In tunnels, on viaducts, or on segregated alignments, metro and LRT systems use standard vignole rails, similar to mainline railways. The choice of profile depends on axle loads and design speed.

49E1 (S49): A common choice for light rail and older metro lines, offering sufficient strength for typical LRV axle loads.
54E1 (UIC54): Used in modern metro systems and heavier LRT lines, providing greater stiffness and durability.
60E1 (UIC60): Deployed in the most demanding metro systems with high traffic frequencies and heavier trains, ensuring maximum track stability and longevity.

For these profiles, steel grades from the EN 13674 standard are used, typically R220 or R260 for tangent track and R320Cr or R350HT for curves.

Rail Clips and Fastening Systems for Urban Rail

Fastening systems in urban environments are a critical component for controlling noise and vibration. The choice of system is guided by the UITP’s focus on passenger comfort and environmental impact. The EN 13481 standard provides the performance framework.

Key Characteristics of Urban Rail Clips and Fastenings

Vibration Attenuation: This is the most important characteristic. Urban fastening systems use soft rail pads and elastic components to isolate the track from the structure (concrete slab or sleeper), preventing ground-borne vibration from reaching adjacent buildings.
Acoustic Performance: The system is designed to reduce rolling noise at the source by damping rail vibrations.
Electrical Insulation: High electrical resistance is mandatory for the reliable operation of signaling systems and stray current control. Stray currents can cause corrosion in nearby utilities and structures.
Adjustability: Systems must allow for precise adjustment of the rail’s vertical and lateral position to maintain tight track geometry tolerances, ensuring a smooth ride.

Performance Parameters for Vibration-Isolating Fastenings (Slab Track)

Parameter	Typical Metro/LRT Requirement	Rationale in Urban Environments
Dynamic Stiffness (kdyn)	Very Low: 10 – 40 MN/m	The single most important factor for vibration isolation. A low stiffness value means the system is “soft” and can effectively absorb vibrations from passing trains, crucial for tunnels under buildings.
Clamping Force	8 – 12 kN per clip	Must be sufficient to restrain the rail but not so high as to compromise the system’s elasticity.
Longitudinal Restraint	> 7 kN	Prevents rail creep due to thermal expansion/contraction and train forces, while allowing for the elastic behavior of the fastening.
Vibration Attenuation	> 30% (or specified in dB)	A direct measure of the system’s ability to reduce vibration transmission. Higher values are required for environmentally sensitive areas.
Electrical Resistance	> 10 kΩ	Ensures signaling integrity and provides a high level of protection against stray current leakage.

Specialized Fastening Systems for Metro and LRT

Several types of fastening systems are used to meet the diverse needs of urban rail.

1. Highly Elastic Slab Track Fastenings

These are the standard for modern metro tunnels. They are anchored directly to the concrete slab and designed for maximum vibration damping. A typical system (e.g., Vossloh 300 UTS, Pandrol Vanguard) includes:

Steel Baseplate: Anchored to the slab.
Elastic Rail Pad: A very soft, thick pad (often >10mm) made from rubber or a similar elastomer. This is the primary vibration-damping element.
Elastic Clips: Provide clamping force without creating a rigid connection.
Angled Guide Plates: Provide lateral support and gauge restraint. The guide plates are often separated from the rail by an elastic element to further reduce noise.

2. Embedded Rail Fastening Systems

For grooved rails in streets, the “fastening system” is the embedding material itself.

Continuous Support: The rail is continuously supported by an elastomeric grout or compound poured around it. This material fills the space between the rail and the concrete channel it sits in.
Function of the Grout: The elastomeric grout provides support, vibration damping, electrical insulation, and prevents water ingress. The properties of the grout (stiffness, adhesion) are carefully specified to ensure long-term performance.

3. Floating Slab Track (FST)

For the most sensitive locations (e.g., under concert halls or hospitals), a Floating Slab Track is used. This is an ultimate solution for vibration control.

System Design: The track slab (the concrete slab supporting the rails and fastenings) is not rigidly connected to the tunnel floor. Instead, it “floats” on heavy-duty rubber bearings or steel springs.
Isolation Principle: This creates a “mass-spring-damper” system that isolates the track slab from the main structure, achieving the highest possible level of vibration and secondary noise reduction (often >25 dB). The rail fastenings used on top of the FST are standard highly elastic systems.