AS 1657 is the Australian Standard that governs fixed platforms, walkways, stairways, and ladders — the access structures that let people work safely at height around plant and equipment. It is one of the most frequently referenced standards in Australian industrial design, and also one of the most frequently got wrong. Over the last 18 months we have reviewed more than 30 platform and walkway designs for civil, structural, and mechanical clients, and the same compliance failures keep reappearing.
This article walks through the seven we see most often, what the standard actually requires in each case, and — crucially — how to fix each one without tearing up the whole design. None of these are exotic. They are the ordinary mistakes that come from designing to memory rather than to the clause.
1. Guardrail height set to the wrong dimension
The most common failure of all: a top rail set below the minimum height the standard requires for the platform’s height above ground. Designers often carry a single “handrail height” number in their head and apply it everywhere, but the requirement is not a single universal figure. The fix is usually straightforward — raising the top rail and adjusting post lengths — and rarely forces a structural redesign, but it must be checked against the actual platform height rather than assumed.
2. Missing or undersized toeboards (kickplates)
Toeboards stop tools and debris falling onto people below, and they are mandatory on platforms above the relevant height. We regularly see them omitted entirely, or specified too short. Adding a compliant toeboard is one of the cheapest fixes on this list because it bolts to the existing edge structure — but it is also one of the most commonly flagged in audit, precisely because it is easy to forget at the modelling stage.
3. Stair pitch and going outside the allowed range
AS 1657 distinguishes between stairways, step-type ladders, and ladders by their angle (pitch), and each has a permitted range. A “stair” drawn at an angle that actually falls into the step-ladder band changes the going, riser, and handrail requirements entirely. We see designs that sit right on a boundary and unknowingly inherit the wrong set of rules. The fix is to confirm which access type the pitch puts you in before detailing the treads, not after — once the geometry is locked, correcting the pitch can cascade into the supporting structure.
4. Inadequate clearances and headroom
Walkways routed under pipework, cable trays, or structural members frequently lose the required headroom, and platforms tucked against equipment lose the required width or side clearance. These are layout failures rather than detailing failures, which is why they are expensive to fix late — the cure is often rerouting the walkway. Catching them early, during the general arrangement, is far cheaper than discovering them at the model-review stage.
5. Gaps and infill that exceed the allowable opening
The space between the top rail and mid rail, and between the mid rail and platform, is limited so that a person cannot fall through. Designs with a single mid rail on a tall guardrail often leave an opening larger than permitted. Adding a second intermediate rail or infill mesh closes the gap and is a minor addition to the rail assembly — but it has to be designed in, because retrofitting mesh to an installed rail is awkward and unsightly.
6. Ladders without the required safety cage or landing provisions
Fixed ladders above a certain height have requirements around fall protection and rest/landing provisions. We see tall single-flight ladders drawn without addressing these, usually because the height crept up during design without anyone rechecking the clause. The remedy depends on the height — sometimes a landing, sometimes an alternative fall-arrest provision — and it is much easier to allow space for it in the layout than to bolt it on afterwards.
7. Detailing to an outdated edition or a mix of editions
Finally, the quiet one: designing against an old copy of the standard, or mixing clauses from different editions because that is what was in the office template. Standards get amended, and a detail that complied a few years ago may not today. The fix is process rather than geometry — work from the current edition, and keep templates under version control so an outdated note does not propagate across every drawing in the set.
The pattern behind all seven AS 1657 mistakes
Almost every one of these comes from the same root cause: applying a remembered rule of thumb instead of checking the clause against the specific geometry in front of you. The platform height, the stair pitch, the ladder height — these are the inputs that decide which requirements apply, and they vary job to job. A design that was perfectly compliant on the last project can fail on this one simply because the height changed.
The good news is that most of these are inexpensive to correct when caught at the general-arrangement or model-review stage, and ruinous only when they reach fabrication. That is the argument for a compliance review before the drawings are issued for construction.
How an AS 1657 compliance review actually works
When a design lands with us for review, we work through it in a fixed order, because the inputs cascade. First we establish the governing dimensions: the height of each platform above the floor or grade below, the pitch of every stair and ladder, and the height of each ladder flight. Those three numbers decide which clauses apply, so they are settled before anything else is checked. A great many “failures” are really just a design built against the wrong assumption about one of these inputs.
From there we check the guarding: top rail height against platform height, mid rail and infill against the maximum opening, and toeboard presence and size on every exposed edge. Then access: stair going and riser consistency, ladder rung spacing, cage or fall-arrest provisions where the height triggers them, and landings on long flights. Finally clearances: headroom along every walkway and width past fixed obstructions. Each item is recorded as compliant, non-compliant, or needs-information, and the non-compliant items are sorted by how much they cost to fix — rail and toeboard changes are cheap, layout-driven clearance failures are not.
The output is a marked-up drawing and a short schedule of findings, so the engineer can see exactly which clause each item relates to and what the lightest-touch remedy is. The aim is never to redesign the structure — it is to get the existing design compliant with the smallest possible change.
Why these slip through in the first place
It is worth being honest about why competent engineers produce non-compliant access designs. It is rarely incompetence. It is that access structures are usually the last thing added to a model — bolted on around plant and structure that are already fixed — so they inherit whatever space is left rather than being designed to the standard from the start. By the time the platform goes in, the headroom under that pipe rack is whatever it is. Designing the access route early, while the surrounding geometry can still move, prevents most of the clearance and layout failures on this list before they happen.
If you have a platform, walkway, or access design you want checked against the standard before it goes out, that is work we do regularly. See our page on AS 1657 fixed platforms and walkways, and send us your general arrangement — we will tell you which of these seven (if any) apply and what the lightest-touch fix is for each.
Note: this article is general guidance, not a substitute for the current published text of AS 1657. Always design and verify against the latest edition of the standard.
