Overview
ISO/TS 18973:2025 - Railway infrastructure - Rail fastening systems - Two directional test method for resistance to repeated loading - specifies a laboratory test procedure to determine the resistance of rail fastening assemblies to repeated, two‑directional loads that simulate real traffic forces. The method uses out‑of‑phase load cycles (a pair of actuators) to generate forces in two directions and takes into account the effect of two consecutive axles. It applies to surface‑mounted rails on sleepers, bearers and slab track and is intended for testing a complete fastening assembly.
Key topics and technical requirements
- Test principle: Static and repeated loads of constant amplitude are applied by two actuators operating out of phase to reproduce realistic lateral and vertical load combinations (see clauses 5, 8.8, 8.9).
- Test sequence: Data collection on a normal rail is followed by tests on a modified test rail for the two‑directional static and repeated load tests.
- Scope limits: Not applicable to web‑supported rails or embedded rails (cannot be tested with modified test rails).
- Apparatus and specimens:
- Pair of actuators and a load application head configured for two‑directional loading.
- Test rail sections (approx. 0.5 m long), displacement and force measuring instruments, strain gauges for rail clips, and fixtures (clause 6).
- Calibration and verification procedures for measuring instruments (clauses 6.5–6.6).
- Measured properties and procedures:
- Clamping force and uplift stiffness (8.3; referenced ISO 22074‑7).
- Longitudinal rail restraint, vertical stiffness (8.4–8.5) and lateral stiffness (8.6; Annex A normative).
- Calculation of test loads and loading angles (8.7; Annex B provides calculation method).
- Detailed static load test (8.8) and repeated load test conditions and results required (8.9).
- Reporting: Test report contents and required results are specified (clause 9).
Applications and users
ISO/TS 18973:2025 is aimed at organizations involved in the design, verification and quality assurance of rail fastening systems:
- Manufacturers testing product durability and compliance during development and production.
- Independent testing laboratories performing type tests and acceptance tests.
- Railway infrastructure owners, designers and maintainers validating fastening performance under service‑representative dynamic and lateral loading.
- Certification bodies and standards committees using standardized methods for comparison and compliance.
Practical benefits include robust assessment of fastening fatigue life, improved prediction of maintenance needs, and consistent benchmarking of fastening solutions under realistic two‑directional loading.
Related standards
- ISO 22074‑1: Vocabulary for rail fastening systems
- ISO 22074‑2: Test method for longitudinal rail restraint
- ISO 22074‑4: Test methods for resistance to repeated loading
- ISO 22074‑7: Test method for clamping force and uplift stiffness
- ISO 22074‑8: Test method for vertical stiffness
Keywords: ISO/TS 18973:2025, rail fastening systems, two directional test method, resistance to repeated loading, railway infrastructure, out‑of‑phase loading, clamping force, uplift stiffness, lateral stiffness.