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Overloaded flatbed: scale ticket, tie-downs and a posted bridge

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Overloaded flatbed: scale ticket, tie-downs and a posted bridge

You are hauling lumber on a 5-axle combination: a tandem-drive tractor with a tare of about 15,000 kg and a tridem flatbed trailer. The load is 14 bundles of kiln-dried lumber, each 6.1 m long, total mass 25,400 kg. The yard scale prints:

  • steer axle 5,600 kg
  • drive tandem 18,600 kg
  • trailer tridem 21,200 kg
  • gross 45,400 kg

The carrier's operating limits are: steer 5,500 kg, drive tandem 17,000 kg, tridem 24,000 kg, gross vehicle weight 39,500 kg. The bundles are held down by six chain tie-down assemblies, each with a working load limit of 2,270 kg; two of them pass over the bare steel edge of the top bundle with no protection. The load is 2.6 m wide and 4.1 m high overall. Your route crosses a bridge with a posted load-limit sign just before the span; the dispatcher says the bridge is "the same as any other on that road, everybody crosses it."

1. Which limits are exceeded, by how much, and exactly what has to change before you leave the yard?

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Compare each line to its limit:

  • Steer: 5,600 vs 5,500 → over by 100 kg.
  • Drive tandem: 18,600 vs 17,000 → over by 1,600 kg.
  • Tridem: 21,200 vs 24,000 → under by 2,800 kg.
  • Gross: 45,400 vs 39,500 → over by 5,900 kg.

Reasoning about the fix: because gross is the largest overrun, no amount of sliding the load around the deck can solve this. Redistribution moves weight between axles; it does not remove it. You must take mass off the trailer.

At 25,400 kg for 14 bundles, each bundle is about 1,814 kg. Removing 3 bundles takes off about 5,443 kg and leaves the gross at roughly 39,957 kg - still 457 kg over. Removing 4 bundles takes off about 7,257 kg, bringing the gross to roughly 38,143 kg with real margin. Take them from the rear first so the tridem, which has room, gives up the weight - then re-check the drives, because the steer is already 100 kg over and any forward shift makes that worse.

Then weigh again. Do not do this arithmetic on paper at the gate and leave. The only number that counts is the printed ticket from a scale with the final load on it, showing every axle and the gross under its limit. Leaving over gross to "sort it out at the next scale" converts a loading error into a series of offences.

2. Assess the cargo securement as loaded, and state what the tie-down system must actually achieve.

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Aggregate working load limit: 6 chains × 2,270 kg = 13,620 kg. The minimum required is 50% of the cargo mass: 0.5 × 25,400 = 12,700 kg. So the aggregate number passes - but only by about 900 kg, and after the load is cut to 10 bundles (about 18,140 kg) the requirement drops to 9,070 kg and six chains are more than ample.

Minimum tiedown count: articles longer than 1.52 m and up to 6.1 m require at least two tiedowns. Your 6.1 m bundles are at the top of that band, so two per article is the floor; six chains over the stack is above the count minimum.

What the aggregate calculation does not tell you:

  • Edge protection. Two chains run over bare steel with nothing between chain and edge. A chain bearing on a sharp edge can be notched or cut, and the edge crushes. Corner protectors are required wherever a tiedown contacts a sharp or wearing surface. A chain with a damaged link has a working load limit of zero, and one failed chain redistributes its share to the others.
  • Tension and binders. Chains must be tight enough that the load cannot move, and over-centre binders need a retaining device so they cannot open.
  • Forward restraint. An aggregate WLL check does not prove the load is blocked against forward movement under hard braking. The stack needs to bear against the headboard or be blocked, not merely pressed down.

Fix the two unprotected chains with corner protectors, check every link and binder, re-tension, then re-scale and re-inspect the load before moving.

3. What does the posted bridge limit mean for you, and how do you handle the dispatcher's comment?

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A posted load limit is a prohibition based on the actual weight of the vehicle and load at the moment of crossing - not the registered weight, not the design weight, and not what other trucks on that road happen to do. If your weighed gross exceeds the posted figure, you may not cross, full stop. You either re-route or you reduce the load until the actual weight is under the posted limit.

The dispatcher's "everybody crosses it" is not information about your weight. It is information about other vehicles whose weight you do not know. The liability and the decision sit with the driver, who is the only person on the scene who can read the sign and the scale ticket together.

The same route check applies to everything else on the way: overall height (you are at 4.1 m, which is close to the general limit - measure it, do not trust the loading sheet), any prohibitory signs on the approach, and any route restrictions that apply to heavy vehicles. A route plan that ignores signs is not a route plan.

If the corrected load is still over the bridge limit, call the dispatcher back with the number and ask for a re-route. That is a normal operational conversation; crossing an over-posted bridge is not.