AS 7633 Railway Infrastructure - Clearances

The objective of this Standard is to manage the risks to safety arising from the interface between rail infrastructure and rolling stock during railway operations. It achieves this by setting out the minimum clearance standards for safe operation between:

• rolling stock (including loads) and trackside structures and equipment; and
• rolling stock (including loads) on adjacent tracks.

This Standard uses key inputs from AS 7507:2026

This product establishes a systematic method for determining kinematic envelopes, contingency outlines, structure outlines and track centres so that authorised rolling stock can operate safely within defined infrastructure clearances. It provides deemed‑to‑satisfy minimum structure outline dimensions and track centres for electrified, non‑electrified and interstate double‑stack operations, allowing these values to be used where suitable instead of undertaking bespoke calculations. It also embeds a risk‑based framework for managing outline infringements, monitoring and maintaining clearances and handling out‑of‑gauge loading, supported by a detailed hazard register and guidance appendices that strengthen consistency and assurance.

The latest review refreshes the clearance methodology and supporting material to align with AS 7507:2026 and contemporary infrastructure and risk management practices, creating a moderate level of change for organisations transitioning from the 2017 edition. Updates include revised structure, terminology and figures that clarify the relationship between AS 7507 and AS 7633 and improve usability, an enhanced calculation framework with clearer definitions and clauses for kinematic envelopes, contingency margins, contingency outlines, structure outlines and combined envelopes for multi‑fleet routes, and an updated deemed‑to‑satisfy clearance table and track tolerance guidance applicable to AS 7507 reference vehicles, speeds up to 160 km/h and double‑stack freight. The review also expands guidance content, including a more comprehensive ARRM hazard register and new or extended worked examples that assist users in navigating the standard and completing clearance calculations.

The product manages the risk of collision or side‑swipe between trains and trackside structures, particularly in constrained environments such as tunnels, platforms and bridges. It also mitigates the risk of train‑to‑train collisions arising from inadequate clearances or track centres under dynamic conditions, as well as the risk of derailment or infrastructure damage caused by insufficient clearance at elements such as side bearers, platforms, overhead equipment or turnout locations. Additionally, it controls risks associated with out‑of‑gauge loads or legacy infringements by ensuring that any departures from the standard are documented, assessed and governed through appropriate controls and operational measures.

Implementation can be achieved by aligning engineering standards and design procedures so that new works and renewals follow the AS 7633 clearance workflow, beginning with determining rolling stock kinematic outlines under AS 7507, calculating kinematic envelopes with track tolerances, applying contingency margins and then defining route‑specific structure outlines and track centres. Organisations can adopt Appendix B deemed‑to‑satisfy dimensions for greenfield or unconstrained locations, while using the calculation procedures and examples from Appendices C to F for constrained or brownfield sites requiring bespoke assessments. Effective implementation also requires establishing or refining risk‑based processes that maintain registers of approved infringements, define inspection and monitoring regimes for clearances and integrate AS ISO 31000‑aligned assessments into modification decisions, out‑of‑gauge approvals and overhead line clearance management.