In Australia, the safety, reliability, and interoperability of the railway network depend on a robust set of engineering guidelines. The Australian Standard (AS) for rails, primarily AS 1085.1, provides the definitive specifications for the design, manufacture, and properties of railway rails. These standards ensure that every rail section can withstand the country’s demanding operational conditions, from heavy haul freight in the Pilbara to urban transit networks.
This technical guide offers a detailed look at the AS Rail Standard, focusing exclusively on the rail profiles and the critical rail clips used to secure them. We will examine the specifications of common AS profiles and the types of fastening systems that maintain track integrity.
Understanding AS Rail Profile Designations
Australian Standard rail profiles are designated by their nominal weight in kilograms per meter (kg/m). For example, an AS 60kg rail weighs approximately 60 kilograms for every meter of length. This system provides a quick reference for the rail’s size and strength. Heavier rail sections are engineered for greater stiffness and wear resistance, making them suitable for mainline tracks with high axle loads and significant traffic, while lighter sections are used for yards, sidings, and industrial applications.
AS 1085.1 outlines the precise geometry, chemical composition, and mechanical properties for each rail profile, ensuring consistency and quality across the industry.
Technical Specifications of Common AS Rail Profiles
The following table details the key dimensions and properties of standard rail profiles as specified under AS 1085.1. These profiles are used across Australia’s diverse rail networks, including heavy haul, freight, and passenger lines.
|
Profile |
Weight (kg/m) |
Height (mm) |
Base Width (mm) |
Head Width (mm) |
Web Thickness (mm) |
|
AS 31kg |
31.5 |
117.5 |
108.0 |
63.5 |
11.5 |
|
AS 41kg |
40.8 |
136.5 |
127.0 |
63.5 |
13.1 |
|
AS 47kg |
46.5 |
141.3 |
127.0 |
70.0 |
14.3 |
|
AS 50kg |
50.6 |
154.0 |
127.0 |
70.0 |
15.0 |
|
AS 53kg |
53.0 |
157.1 |
146.0 |
70.0 |
14.7 |
|
AS 60kg |
60.6 |
170.0 |
146.0 |
70.0 |
16.5 |
|
AS 68kg |
67.5 |
185.7 |
152.4 |
74.6 |
17.5 |
Material Properties and Performance
Beyond dimensions, AS 1085.1 specifies the crucial mechanical properties and chemical composition that dictate a rail’s performance. The standard defines grades for both plain carbon steel and “Head Hardened” (HH) rails, which undergo a special heat treatment process to increase the hardness of the rail head for enhanced wear resistance.
Mechanical Properties (Minimum Values)
|
Profile |
Grade |
Tensile Strength (MPa) |
Surface Hardness (HBW) |
|
AS 31kg, 41kg |
Plain Carbon |
≥ 700 |
– |
|
AS 47kg to 68kg |
Plain Carbon |
≥ 880 |
≥ 260 |
|
AS 50kg to 68kg |
Head Hardened |
≥ 1130 |
≥ 340 |
Chemical Composition (%)
The chemical makeup is tightly controlled to produce steel that is strong and wear-resistant but not so brittle that it fractures under stress.
|
Element |
AS 31kg, 41kg (%) |
AS 47kg to 68kg (%) |
|
Carbon (C) |
0.53 – 0.69 |
0.65 – 0.82 |
|
Manganese (Mn) |
0.60 – 0.95 |
0.70 – 1.25 |
|
Silicon (Si) |
0.15 – 0.58 |
0.15 – 0.58 |
|
Phosphorus (P) |
≤ 0.025 |
≤ 0.025 |
|
Sulfur (S) |
≤ 0.025 |
≤ 0.025 |
These specifications ensure that every rail manufactured to the AS standard can perform reliably, whether it’s part of a heavy haul iron ore line in Western Australia or a passenger line in a major city.
Rail Clips in Track Stability
A rail system is only as strong as its weakest link. Rail clips are a vital component of the track fastening system, tasked with holding the rail securely to the tie (sleeper) and tie plate. A failure in the fastening system can lead to serious track defects, such as gauge widening or rail rollover, which pose a significant derailment risk.
The primary functions of rail clips are to:
- Maintain correct track gauge.
- Provide a strong clamping force to prevent vertical movement of the rail.
- Offer longitudinal restraint to manage the expansion and contraction of continuously welded rail (CWR).
Common Types of Rail Clips Used in Australia
The type of rail clip used often depends on the application, the type of sleeper (timber, concrete, or steel), and the operational demands of the track.
1. Elastic Rail Clips
Elastic clips are the modern standard for most freight and passenger lines in Australia. Made from high-grade spring steel, they are designed to provide a consistent clamping force while allowing for the small, dynamic movements of the rail as a train passes.
- Design: These clips often feature a “J” or looped shape, like the widely used Pandrol e-Clip or Fastclip systems. They are driven into a cast-in shoulder on a concrete sleeper or a housing on a steel or ductile iron tie plate.
- Function: Their spring-like nature is their key advantage. They can absorb energy and flex without permanent deformation, ensuring the rail remains clamped. This is essential for managing the high thermal and dynamic stresses in CWR track, preventing buckling and pull-aparts.
- Application: Used extensively with heavier profiles like AS 60kg and AS 68kg rail on concrete sleepers in heavy haul corridors and mainlines.
2. Bolted Clips
Bolted clips are a more traditional fastening method but remain in use for specific applications where high clamping force and rigidity are prioritized.
- Design: These systems use a rigid metal clamp that is tightened against the rail flange with high-tensile bolts. The bolts are anchored into the sleeper or tie plate.
- Function: They provide a very secure, non-yielding grip. However, their lack of elasticity can be a disadvantage under heavy dynamic loads, as vibrations may cause bolts to loosen over time.
- Application: Often found in special trackwork (e.g., turnouts and crossings), on tracks with jointed rail, and in industrial settings like crane runways where longitudinal rail movement must be strictly prevented.
3. Welded Fastening Systems
The Welded clips are a specialized solution for securing rails to steel structures, such as on bridges or in port facilities.
- Design: This system involves a baseplate or lower component that is welded directly onto a steel girder or deck. A separate forged clip is then bolted to this welded base to clamp the rail.
- Function: This method creates a strong and reliable fastening point without the need to drill holes, which could compromise the structural integrity of the steel support structure.
- Application: The primary use is for crane rail installations and for track on steel-deck bridges where a direct rail-to-steel connection is required.
Welded Crane Rail Forged Fastening Clamp XINGRAIL 9220/20/45
XINGRAIL Welded Crane Rail Forged Fastening Clamp 9116/08/3
Welded Crane Rail Forged Fastening Clamp XINGRAIL 9216/08/40
XINGRAIL 7216/20/39 Welded Crane Rail Forged Fastening Clamp
Welded Crane Rail Forged Fastening Clamp XINGRAIL 9120/15/38
The Australian Standard, through documents like AS 1085 series, ensures that rails and their associated components are manufactured to a high degree of quality and consistency. By defining everything from dimensional tolerances to material properties, these standards provide the foundation for a safe, efficient, and interconnected national railway network. The proper application of these rail profiles, combined with robust and reliable fastening systems, is fundamental to the successful operation of Australia’s railways.
