The 16:40 Loading That Must Reach the Port Gate by 18:00
A medium flat-bed truck (車両総重量 7,980 kg, tare 3,200 kg, maximum payload 4,780 kg, rear-axle rating 5,200 kg, deck height 1,300 mm) is loaded at a factory in Aichi for a 40 km run to Nagoya Port. The consignment is 14 pallets of castings, 380 kg each, stacked two high. Loading finishes at 16:40 and the driver must clear the port gate before 18:00.
At the depot scale the axles read: front 2,750 kg, rear 5,770 kg. The top of the load stands 3,860 mm above the ground. The planned route crosses a bridge posted 3.5 m and a tunnel posted 3.8 m; both sit on the only road that avoids a 12 km detour. Light rain is falling and the pallets are uncovered. The driver says the scale must be faulty, because the truck 'sits level on its springs'.
1. Using the figures given, identify every limit the loaded vehicle exceeds. Which of these are legal limits and which are manufacturer ratings, and does the distinction change what the driver must do?
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Three figures fail at once.
Vehicle gross weight (legal). 3,200 kg tare + 5,320 kg load = 8,520 kg against a 車両総重量 of 7,980 kg - 540 kg over. This is the 過積載 prohibition of 道路交通法第57条, and the 車検証 figure is the ceiling: it applies even if the truck looks level and the springs have not flattened. Penalties fall on the driver, the operator and, under 貨物自動車運送事業法, the shipper who ordered the load.
Payload (legal). 5,320 kg against 4,780 kg - 540 kg over, the same excess seen from the other side.
Rear axle (manufacturer rating). 5,770 kg against 5,200 kg. This is not a road-law weight limit (the 車両制限令 axle limit is far higher), but exceeding it overloads the tyres, springs and rear brakes and changes handling. It is still a defect that must not be driven.
The distinction matters: the axle figure is a mechanical argument for redistributing load, but redistribution alone cannot cure the gross-weight breach. The truck must not leave.
2. The driver proposes sliding four pallets forward to bring the rear axle under its rating and then departing. Evaluate that plan and state what must be true before the truck leaves the factory.
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The plan is half-sound and wholly insufficient.
Moving four pallets (1,520 kg) forward will drop the rear axle reading and probably bring it under 5,200 kg, but the total stays 8,520 kg. Gross weight is independent of where the load sits, so the 過積載 breach survives the fix. The driver would also need to re-weigh to confirm he has not pushed the front axle past its own rating - a figure he has not been given and must look up in the 車検証 and the body builder's specification.
The minimum correct action is to remove at least 540 kg - in practice two pallets, 760 kg, giving 7,760 kg gross, a margin for scale error and road spray soaking the load. Then: re-weigh each axle; confirm front and rear are within their ratings; confirm the load height; confirm the route.
Until those four checks are done and recorded, the answer to 'can it go?' is no. The 18:00 cut-off is the dispatcher's problem, not a reason to drive an overloaded vehicle.
3. Assuming the load is cut back to a legal gross weight, what must be done about the load height, the route, and securing the load in rain?
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Height. The general limit is 3,800 mm (車両制限令), and 3,860 mm already exceeds it, so the vehicle needs a 特殊車両通行許可 from the road administrator - an application measured in days, not hours. More decisively, the 3.5 m bridge cannot be passed at any height above 3.5 m under any permit. Restacking to a single tier, roughly 2,560 mm on this deck, removes both problems and is the practical answer; the second tier travels on a second run.
Route. Even at a reduced height, confirm the chosen road against the posted limits rather than assuming the tunnel figure covers the bridge.
Securing. Rain on uncovered pallets adds water weight and lets banding stretch. Cover with a tarpaulin or シート for 飛散防止 and load shift, use at least four rated ラッシングベルト over the load, tension them evenly, and re-check tension after the first 10 minutes and again within the first 50 km. Castings are dense: a single shifted pallet will go through the headboard.