Axle overload and inadequate restraint on a steel-plate load
You are loading twelve steel plates, each 12 m long and 2.2 t, onto a flatbed semi-trailer. The tractor has three axles and the trailer three axles. The weighbridge reads: steer axle 6.8 t, drive axles 14.2 t, trailer axles 25.5 t, total 46.5 t. The permit allows 44.0 t gross, with limits of 7.5 t on the steer axle, 13.0 t on the drive group and 24.0 t on the trailer group. The plates are stacked 1.9 m high, their front edges 1.2 m behind the trailer headboard, and secured with two 50 mm ratchet straps over the top. The steel is dry and unpainted. The loader says the load “has never moved before” and wants to depart immediately because the customer is waiting.
1. Calculate the overload and identify which axle groups are over their limits.
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Total is 6.8 + 14.2 + 25.5 = 46.5 t, which is 2.5 t over the 44.0 t permit. The steer axle is 6.8 t against 7.5 t, so it is legal with 0.7 t spare. The drive group is 14.2 t against 13.0 t, so it is 1.2 t over. The trailer group is 25.5 t against 24.0 t, so it is 1.5 t over. The axle-group excesses total 2.7 t, slightly more than the gross excess, which shows the load is both too heavy overall and poorly distributed. Simply moving plates rearward would make the trailer group worse; moving them forward would add load to the steer and drive axles. The driver must not depart. At least 2.5 t must be removed, the remaining load repositioned, and the vehicle re-weighed before a permit-compliant dispatch decision.
2. How should the load be redistributed and secured for the journey?
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First remove enough plates to bring gross and every axle group within the permit, then re-weigh each axle. Distribute the remaining plates so the centre of gravity sits as low and as near the trailer's designed load centre as possible, without overloading the drive or trailer groups. Steel plates are slippery and have little friction, so two straps over the top are inadequate. Use direct restraint: rated chains or straps through or around the plates, with edge protectors, tensioners and anti-slip matting. Use at least four restraint points, arranged in pairs to prevent forward, rearward and lateral movement; longitudinal restraint is critical during braking. Recheck tension after the first few kilometres, then at each stop. The driver remains responsible for confirming the load is secure, even if a loader or customer disputes it.
3. What records and communication should follow if the loader refuses to reduce the load?
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The driver should refuse to move and inform the transport manager or dispatcher in writing, stating the weighbridge readings, permit limits, the calculated excess and the securement deficiency. The weighbridge ticket should be retained and the refusal recorded in the vehicle or defect log. The customer should be told that the vehicle cannot legally or safely depart until the load is corrected. If the operator pressures the driver to proceed, the driver should escalate the matter and, where required, report it to the relevant authority. The key reasoning is that an overloaded vehicle affects steering, braking and tyre capacity, while an unsecured steel load can shift or penetrate the cab in a stop. “It has never moved before” is not evidence of adequate restraint; physics and the permit limits decide the issue.