6.3 Load Placement, Distribution, Overhang Limits, and Load Security Checks

A load that is beautifully restrained can still roll the truck, overload an axle, or scrape a cyclist at a kerb if it is placed badly. Placement and distribution are tested alongside restraint because they are part of the same legal duty under Part 3.4 of the HVNL.

Centre of gravity: low and centred

The single most important placement principle is to keep the centre of gravity (CoG) low and near the vehicle centreline. A high CoG raises rollover risk because cornering forces act on a longer lever arm from the contact patch; an off-centre CoG biases weight to one side and makes the vehicle unstable in swerves and on cross-fall roads. Practical placement rules:

• Place heavy items at the bottom of the stack and light items on top.
• Stack items so that the combined CoG sits as close to the longitudinal centreline of the vehicle as possible — for asymmetrical loads, counterbalance rather than pile to one side.
• Where possible, place dense items over or just ahead of the drive axle group, where the chassis is strongest and the mass is carried by the suspension designed for it.
• Avoid loading the rear overhang with heavy items — mass behind the rear axle group unloads the steer axle and reduces steering control, and it magnifies the vertical bounce of overhanging mass.

Axle mass distribution

Mass must be distributed so that no axle exceeds its legal mass limit and the steer axle retains enough loading for steering. Key limits relevant to a heavy rigid vehicle (from the NHVR mass limits, as applied in Victoria):

• Steer axle: 6 t (single-tyred steer).
• Single drive axle: 10 t.
• Tandem drive axle group: 16.5 t (road-friendly) or as specified for the vehicle.
• GVM: the manufacturer's plated gross vehicle mass — the sum of all axle loads must not exceed it.

A poorly distributed load can put a vehicle over an axle limit even when the total mass is under GVM. Load forward of the drive axle adds to the steer axle; load behind the rear axle subtracts from it. The aim is an even spread that keeps every axle within its limit and leaves the steer axle with enough load for positive steering (typically at least 25% of the steer axle's rated capacity).

Overhang limits

Beyond the loaded mass, the dimensions of the load are capped by the HVNL dimension limits. Projecting loads are allowed within strict overhang limits; beyond them the load is over-dimension and requires a permit, flags and often pilot vehicles.

Note the rear overhang is the tighter of two tests — you take the smaller of 3.7 m and 60% of wheelbase, not the larger. A rigid truck with a 5 m wheelbase has a 60% value of 3 m, so its rear overhang limit is 3 m, not 3.7 m. This is a classic exam trap.

Any load that projects beyond these limits is treated as over-dimension: it must display flags (visible during the day) and clearance lights at night, may need a pilot/escort, and usually requires an oversize/overmass permit from NHVR or VicRoads. The driver must plan the route around approved OD routes and avoid low-clearance structures.

Pre-departure load security checks

Before driving off, walk around the load and inspect every component of the restraint system. Restraint equipment fails in serviceable-looking ways — the defect is often invisible until you look closely.

Chains

• Look for stretched, bent or cracked links — stretch indicates the chain has been overloaded; cracked links are immediate withdrawal-from-service defects.
• Check the lashing capacity stamp is legible; if you cannot read the LC, you cannot prove the chain meets the standard.
• Ensure the chain is tensioned with a turnbuckle or over-centre dog, not just pulled up by hand and hooked.
• Verify edge protectors are in place wherever the chain contacts a sharp load edge.

Turnbuckles

• Check the threads are clean and the body is not bent; a bent turnbuckle can fail to hold tension.
• Confirm the turnbuckle is locked (either a jam nut or safety wire) so vibration cannot back it off.
• Make sure the turnbuckle has threads showing both ends — fully screwed in one end means it cannot take up any future slack.

Shackles and connectors

• Check the pin is fully screwed in and secured (cotter pin or mouse if applicable).
• Ensure the shackle body is not side-loaded — shackles are rated for in-line loads; side loading dramatically cuts their capacity.
• Verify rated shackles only — never use lifting shackles of unknown provenance for transport restraint.

Twist locks

• For containerised or flat-deck ISO loads, confirm every twist lock is positively engaged and in the locked position (the handle should be in the locked detent, not just resting).
• Visually confirm each corner casting is seated on the twist lock with no gap.

Tarpaulins and load covering

• Inspect the tarpaulin for tears, holes and worn patches — a flapping tarp can shred in the wind and either depart the vehicle or whip a following road user.
• Check rope ties, eyelets and tie-down rings are intact and tight; loose rings let the tarp flap and wear through.
• Confirm the tarp is not carrying load restraint duty unless it is a purpose-built restraint tarp — most tarps only cover the load, they do not restrain it.

In-trip checks

Restraint is not "set and forget." Two checkpoints matter:

1. First-stop re-tension. After 20–50 km, stop and re-tension every lashing. New dunnage beds in, webbing stretches under load, and chains seat into the load. The first stop is when the system settles and most slack appears.
2. Periodic walk-around. At every rest stop, fuel stop and work-diary break, walk around the load. Look for shifted items, loose or cut straps, bent chains, dropped turnbuckles, torn tarps and any sign of movement. Re-tension anything that has relaxed.

A load that has shifted is a warning, not a curiosity: if it moved once, the restraint in that direction is not meeting the 0.8g / 0.5g / 0.2g standard. Re-stack and re-restrain before continuing — a second shift may take it off the vehicle.