ISO 12494:2017

Overview

ISO 12494:2017 - Atmospheric icing of structures provides principles for assessing ice accretion and the resulting loads on exposed structures. It guides designers and engineers in determining ice mass, wind actions on iced structures, and related effects (static, dynamic and falling ice). The standard emphasizes site-specific knowledge - especially the use of ice classes - and recommends designing for some ice rather than none to improve safety and resilience.

Key topics

• Scope and applicability: Intended for masts, towers, antennas, cables and stays, ropeways, ski-lift structures, buildings or parts exposed to icing, and special towers (e.g., wind turbines, transmission-line towers). Electrical overhead line icing is covered by IEC standards, but ISO 12494 can be used for associated mast structures.
• Icing types and fundamentals: Definitions and characteristics of glaze, wet snow, rime, and other icing types; topographic and height-related variations affecting accretion.
• Ice classes (IC): Use of site-based ice classes to represent “normal” icing amounts; guidance on estimating ice class where measurements are unavailable.
• Load effects: Static ice loads, increased wind load on iced members (increased exposed area and drag coefficient), dynamic effects, unbalanced ice loading on guys, and falling ice hazards.
• Wind action & drag coefficients: Treatment of single members and lattice structures, including angle of incidence and design implications.
• Annexes (informative): Formulae, standard measurement practices, theoretical icing models, climatic estimation of ice classes, and practical usage hints.

Practical applications

ISO 12494:2017 is used to:

• Determine ice mass and combined ice-plus-wind loads for structural design and safety checks.
• Inform retrofits, site selection, and maintenance planning where atmospheric icing is a risk.
• Support decisions where no local icing data exist by providing methodologies to estimate ice classes (consultation with meteorologists or local experts recommended).
• Evaluate parts of structures most vulnerable to icing (e.g., antenna elements, guy ropes, rotor blades).

Who uses it:

• Structural and civil engineers, design offices and consultancies
• Wind-turbine and telecom tower designers
• Utilities, ropeway and ski-lift engineers
• Infrastructure owners, asset managers, and meteorologists

Related standards

• Use in conjunction with ISO 2394 (general principles on reliability of structures).
• For electrical overhead lines, consult relevant IEC standards (ISO 12494 can still inform design of non-electrical support structures).

ISO 12494:2017 helps ensure safer, more resilient designs by integrating atmospheric icing considerations into structural engineering practice.