Portable Warning Triangles: Carriage, Placement, and AS 3790

Portable Warning Triangles: Carriage, Placement, and AS 3790

Quick Answer: Every heavy vehicle with a Gross Vehicle Mass (GVM) over 12 tonnes must carry three portable warning triangles that meet AS 3790 (the Australian Standard for portable warning triangles). When the vehicle stops on or partly on a road and is a hazard to other traffic, you must place triangles to warn approaching drivers. On roads signed 80 km/h or higher, place the first triangle 200–250 metres behind; on roads under 80 km/h, place it 50–150 metres behind. Use all three triangles on high-speed roads; one is enough on lower-speed roads.

Why Triangles Matter

A broken-down heavy vehicle on a high-speed road is a lethal obstacle. A car travelling at 100 km/h covers roughly 28 metres per second — a driver who spots your truck only 100 metres away has under four seconds to react and stop. Triangles give approaching drivers warning time to slow down, change lanes, or stop safely. They are not optional courtesy; they are a legal requirement under the Heavy Vehicle National Law (HVNL) as applied in Victoria, and a core duty for any HR licence holder.

Carriage Requirements

How many triangles must you carry?

• Three portable warning triangles, carried in the cabin or an accessible storage compartment.
• The triangles must comply with AS 3790 — Portable warning triangles for motor vehicles. This standard specifies the reflective material, fluorescent orange-red colour, minimum size (typically 380 mm per side), folding mechanism, and stability in wind.
• Triangles must be in good condition — faded, cracked, or non-reflective triangles do not comply, even if they once met the standard. Inspect them in your daily pre-start check.
• Carry them in any heavy vehicle with GVM over 12 tonnes, including a rigid HR vehicle, whether loaded or empty. The requirement attaches to the vehicle, not the load.

When must you place triangles?

You must place triangles whenever your heavy vehicle is stopped on or partly on a road and could be a hazard to other road users. This includes:

• Breakdowns and mechanical failure
• Tyre failure or wheel issues
• Load shifts requiring re-strap
• Crashes, even minor ones
• Any stop on a freeway shoulder or in a live traffic lane

A planned stop at a designated rest area or truck bay does not require triangles, because you are not a hazard. A stop on a roadside shoulder or breakdown lane generally does, because other traffic is moving past you at speed.

Placement Distances

The placement rule is speed-limit-based. Know the speed limit of the road you are on before you place triangles.

Three-triangle placement on high-speed roads

On a road signed 80 km/h or above, place all three triangles:

1. First triangle — 200–250 m behind the vehicle, on the same side of the road, in or adjacent to the traffic lane the disabled vehicle is occupying.
2. Second triangle — 200–250 m behind, offset laterally so oncoming drivers see a graduated warning (some guidance places the second triangle a further 50–100 m back, but the HVNL baseline is the 200–250 m band for the warning zone).
3. Third triangle — beside the disabled vehicle or between it and the first triangle, so drivers who missed the first warning get a second before reaching you.

Always place triangles on the same side of the road as your vehicle. A triangle on the opposite side is harder to see and can be missed by the drivers who need it most.

Worked Example: Breakdown at 100 km/h

You are driving a 22-tonne HR rigid truck on the Hume Freeway, speed limit 100 km/h, and a rear axle bearing fails. You pull onto the shoulder and stop.

1. Switch on hazard lights and headlights immediately.
2. Check the speed limit: 100 km/h is 80 km/h or higher, so use all three triangles and place the first one 200–250 m back — round up to 250 m to give maximum warning at the higher speed.
3. Walk back along the shoulder, keeping off the live traffic lane. Pace or estimate 250 m (roughly 250 large paces).
4. Place the first triangle on the shoulder side, reflective face toward oncoming traffic.
5. Place the second triangle a further 50 m back (about 300 m total from your truck).
6. Place the third triangle between the first triangle and your truck.
7. Stay behind the barrier or well clear of the traffic lane. Call for assistance.

Worked Example: Breakdown at 60 km/h

You are on a regional road signed 60 km/h and your truck loses drive. Because the limit is under 80 km/h, place one triangle 50–150 m behind — choose the upper end (150 m) if you are just over a crest or round a bend, the lower end (50 m) if visibility is long and straight.

Common Exam Traps

• Trap 1: "Two triangles are enough on a freeway." Wrong — high-speed roads (80 km/h+) require three. One or two is a breach.
• Trap 2: "Place the triangle on the opposite side of the road for better visibility." No — same side as the vehicle, facing oncoming traffic.
• Trap 3: "Triangles are only required when loaded." No — the requirement is tied to GVM over 12 tonnes, not to the load. An empty HR rigid still needs them.
• Trap 4: "Any orange triangle will do." No — the triangle must comply with AS 3790. A homemade or non-compliant triangle does not satisfy the law.
• Trap 5: "You can skip triangles if hazard lights are on." No — hazard lights are required as well as triangles, not instead of them.

Inspection and Maintenance

• Check triangles in your daily pre-start: confirm three are present, clean, undamaged, and reflective.
• Replace faded or cracked triangles immediately — they no longer meet AS 3790.
• Store them where they will not be damaged by load movement or weather.
• If you drop a triangle on the road while placing it, do not chase it into live traffic; wait for a gap.

Victorian Enforcement

Victoria Police and the Transport Safety Service (TSS) can inspect your vehicle at any time, including at roadside stops and weighbridges. Missing, non-compliant, or incorrectly placed triangles are a separate offence from any breakdown-related offence. A breach of the HVNL triangle requirement typically attracts a fine and may add demerit points to your Victorian licence. The driver is the first person prosecuted, but under Chain of Responsibility, the operator can also be liable if they failed to supply compliant triangles.