A semi-trailer combination can be perfectly legal on total weight and still get pulled over for an axle violation. The kingpin can be carrying too much, the drive axle of the tractor can be over the limit, the trailer tridem can be sitting on more than it is allowed. Total weight is one number, but European law cares about every axle independently. Two truckers leaving the same warehouse with the same 24 tonnes of cargo can end up with very different results at the next weighbridge, depending on where the heavy pallets are sitting.
This guide walks through the European axle load limits, why distribution matters more than most people assume, and how the live axle view in the 3D Load Planner takes the guesswork out of it.
The live axle view in LoadPlanner
The 3D Load Planner shows the axle loads of the selected vehicle in real time, updated as you add, move, or remove cargo. When you pick a vehicle template, the planner reads its axle configuration; when you place cargo, it updates the readings on the front axle, drive axle, and trailer axles continuously. If an axle goes over its limit, the bar turns red.
The video above shows the panel as cargo is added and moved around the trailer. The axle bars react to every change. Drop a heavy pallet near the front and the drive axle reading climbs immediately; slide it back and both the drive and trailer readings re-balance. There is no save, no recalculate button. The numbers move with the cargo.
This makes the planning loop fast: place cargo where you think it should go, glance at the axle bars, adjust if anything is red. The whole cycle for a typical 33-pallet load takes a few minutes instead of being a guess that gets checked at the weighbridge.
A note on accuracy: the readings are theoretical, based on the axle positions and empty weights set in the vehicle template. They assume a level surface, even tire pressure, no fuel sloshing, no driver weight, none of the dozen smaller factors that change the real reading at the weighbridge by a few percent. Use them as a planning tool. The official number is still what the weighbridge prints.
The EU axle load limits
Directive 96/53/EC sets the maximum permitted axle load for every common configuration on European roads. The headline numbers, the ones that catch most loads:
| Axle configuration | Maximum load |
|---|---|
| Single non-driving axle | 10 000 kg |
| Single driving axle | 11 500 kg |
| Tandem non-driving (≥ 1.8 m spacing) | 20 000 kg |
| Tandem driving (≥ 1.8 m, air suspension) | 19 000 kg |
| Tridem on trailer (≥ 1.4 m spacing) | 24 000 kg |
Member States can apply slightly different domestic rules in some categories, but these are the values used for cross-border transport, and they are the ones that show up on every weighbridge ticket. Most enforcement focuses on three points: the front (steering) axle of the tractor, the drive axle of the tractor, and the trailer tridem.
The total combination is capped at 40 tonnes for general transport (44 tonnes for intermodal containers in many countries), but that ceiling is separate from the per-axle ceiling. A 40-tonne combination with 13 tonnes on the drive axle is overloaded even though the total is fine.
Why total weight alone is not enough
Imagine the same load planned three different ways: 24 tonnes of palletised cargo on a standard tractor + semitrailer, gross combination weight 38 tonnes. All three are under 40 t total. None of them are equally legal.
Plan A: heavy pallets stacked at the front of the trailer, near the kingpin. The drive axle of the tractor takes a disproportionate share of the cargo weight, and on top of the empty tractor's drive-axle load it ends up at around 12.5 tonnes. Over the 11.5 t limit. The trailer tridem is sitting at 17 t, well under its 24 t limit, but that does not save the plan. The next weighbridge prints a violation.
Plan B: heavy pallets at the back of the trailer, near the rear doors. Now the trailer tridem is carrying most of the cargo and shows 25 t at the weighbridge. Over the 24 t limit. The drive axle is fine at 9 t. Same total cargo, different overload.
Plan C: heavy pallets distributed across the length of the trailer, with the centre of mass roughly between the kingpin and the trailer tridem. Drive axle 10.5 t, trailer tridem 21 t, steering axle 7 t. Every axle under the limit, total still 38 t. Legal.
The cargo did not change. The placement did. And the difference between legal and illegal is not visible to the driver from the outside of the trailer.
What happens when an axle is overloaded
Overload is one of the few violations that has consequences across legal, financial, and operational dimensions at the same time.
Legal: most European countries fine on a sliding scale from a few hundred euros to several thousand, depending on the percentage of overload and the country. Repeat offences carry driver licence points. In some jurisdictions a serious overload means the trailer is impounded until the load is partially removed and reweighed, which means an unscheduled stop, an unscheduled forklift, and an angry customer waiting at the destination.
Insurance: a cargo or vehicle insurance claim can be reduced or denied if the vehicle was overloaded at the time of the incident. This is the quiet one. The fine is unpleasant; the denied claim after an accident is the one that closes companies.
Tire wear: an axle that is 20% over its limit wears its tires roughly twice as fast. This is not linear, it is closer to a fourth-power relationship. A persistently overloaded axle is a hidden cost line on every set of tires the operator buys.
Suspension and brakes: shock absorbers, air bellows, brake drums and discs all wear faster on overloaded axles. Braking distance also increases, which matters in any emergency.
Road damage: this is why the limits exist in the first place. A heavy axle does dramatically more damage to road surfaces than a light one, which is why some countries charge tolls per axle and why the limits are enforced. As an operator, the relevance is mainly that road authorities treat axle overload as a serious matter and enforcement is rising in most countries.
How to distribute weight properly
The principle is simple: spread the centre of mass of the cargo across the length of the trailer so that no single axle group is forced to carry a disproportionate share. The execution is harder, especially with mixed cargo.
A few rules of thumb that hold for most loads:
- Heavy items toward the middle of the trailer, roughly between the kingpin and the trailer axle group. This is the "sweet spot" where a kilo of cargo splits roughly evenly between the tractor and the trailer.
- Avoid concentrating all heavy pallets at one end. Even if there is empty trailer space at the other end, an unbalanced load is what triggers axle violations.
- Stack heavier items at the bottom, lighter on top. Beyond the stacking limits of the cargo unit itself, the centre of mass also matters for stability around corners and on lateral grades.
- For multi-stop loads, think about what comes off first. As the trailer empties, the weight distribution changes. A trailer that is well balanced fully loaded can become overloaded on one axle group after the first drop if all the weight was at the front.
- Check axle weights before departure, especially on heavy loads. Some weighbridges allow individual-axle readings.
These are the easy rules. The hard part is doing them with a heterogeneous load, mixed pallet weights, and a tight schedule. This is where planning software becomes useful.
Why intuition is not enough
Working out axle loads correctly is harder than it looks. Every axle in a tractor + semitrailer combination sits at a different distance from the kingpin and from the centre of mass of the cargo, and the share of weight that each axle ends up carrying depends on those distances and on the empty weight of the tractor and trailer themselves. Doing the maths by hand for a 30-pallet load with mixed weights is theoretically possible. In practice, nobody does it. Most loads are arranged by intuition: by what looks balanced, by the way the last similar load was done, by a driver's experience.
Intuition gets close. It does not get exact. And the difference between close and exact is what fines, denied claims, and unscheduled reloads are made of. A trailer that should have read 21 t on the tridem and actually reads 22.5 t can quietly cross a hundred weighbridges before someone enforces the limit, and then the operator pays for all of those trips at once.
Calculated distribution flips this. With the load plan computed up front, the placement specification can be sent to everyone involved before loading even starts: the driver knows where each pallet goes, the loader at the warehouse knows the sequence, the customer or shipper sees what is coming. Loading happens once, correctly, instead of being done by feel and re-done at the weighbridge stop. The plan, the load, and the weighbridge ticket all agree, and the cost of an unscheduled reload (driver hours, forklift availability, missed delivery window) disappears from the operation.
This is the part the planner does that paper cannot: compute the share of weight on every axle as cargo is placed, against the legal limits for the specific vehicle template selected, and produce a sharable specification of the result.
A pre-departure checklist
If you are using the live axle view, a short pre-departure check covers most situations:
- Every axle bar in the green, including with a partial unload simulated if the route has multiple drops
- Cargo positions match what the planner shows (no last-minute reshuffling on the loading dock without re-planning)
- The driver has the PDF load plan with axle figures so they can defend the load at a weighbridge if asked
- Heavy items secured against shifting forward under braking, which can turn a well-balanced load into a front-overloaded one in a single hard stop
The cost of a violation is high. The cost of opening the planner for two extra minutes is zero.
Summary
European axle load limits exist for road safety, road preservation, and equal treatment between operators, and they are enforced. A combination can be perfectly legal on total weight and still be overloaded on an axle, and the difference is purely about where the cargo sits on the trailer. Distributing weight across the length of the trailer, keeping heavy items near the middle, and watching for the axles that empty last in a multi-stop sequence are the standard practices that keep loads legal. The live axle view in the 3D Load Planner turns this from a guess into a fact, visible while planning instead of confirmed at the next weighbridge.
Next in this series: planning load order, why the sequence in which cargo is placed matters as much as the placement itself, and how to think about multi-stop loads.