Heavy cargo is a load that exceeds the vehicle's maximum total weight or axle weight even if its dimensions remain within the legal limits. In Türkiye, when 40 tonnes for a combination with five or more axles, 10 tonnes for a single axle or 11.5 tonnes for a drive axle is exceeded and the load cannot be divided, a Special Load Transport Permit (Özel Yük Taşıma İzin Belgesi) must be obtained from the General Directorate of Highways (KGM).
Are heavy cargo and out-of-gauge cargo the same thing?
No. Out-of-gauge cargo exceeds the width, height or length limit. Heavy cargo stays legal in terms of dimensions but exceeds the weight limit. For example, a press 2.4 m wide, 6 m long and weighing 55 tonnes fits on a standard trailer; even so, it cannot be carried without a permit because it exceeds the legal combination weight. In practice, large transformers, castings and compact construction machines can fall into both categories at once.
Above what tonnage is a permit required?
The thresholds are in Article 128 of the Highway Traffic Regulation (Karayolları Trafik Yönetmeliği). Total weight and axle weight are checked separately; if either is exceeded, the vehicle is outside the limits.
| Vehicle / axle | Maximum weight |
|---|---|
| Non-driven single axle | 10 tonnes |
| Driven single axle | 11.5 tonnes |
| Tandem axle group on a semi-trailer (spacing 1.3–1.8 m) | 18 tonnes |
| Tri-axle group (spacing 1.3–1.4 m) | 24 tonnes |
| Four-axle vehicle with trailer or semi-trailer | 36 tonnes (38 tonnes if the semi-trailer axle group is 20 tonnes) |
| Combination with five or more axles | 40 tonnes |
| Three-axle tractor + semi-trailer carrying a 40 ft ISO container | 44 tonnes |
As the unladen weight of the tractor and trailer together is about 14–16 tonnes, the net payload a standard truck can carry is usually 24–26 tonnes. An indivisible piece exceeding this value is considered heavy cargo.
How does weight affect roads and bridges?
Pavement damage increases not linearly with axle load but roughly with its fourth power. According to this widely used engineering rule, when the axle load doubles, the damage to the asphalt grows about 16 times. That is why the aim in heavy cargo transport is to spread the total weight over many axles. On modular hydraulic trailers, the number of axle lines is increased so that the load per axle line is brought down to an acceptable level.
For bridges and culverts, what matters is the total effect of the load on the span. A 100-tonne load concentrated over a short distance is more demanding than the same weight distributed over a long vehicle. KGM may therefore carry out a separate review of the structures along the route for very heavy transports (see bridge and culvert checks).
How is a permit obtained, and who is responsible?
- Indivisibility: A permit is only granted for a load that cannot be broken down into parts. Equipment that can be dismantled is required to be shipped in parts (see indivisible load).
- Vehicle selection: The number and spacing of axles, and the weight on each axle when laden, are calculated.
- Application: The vehicle operator or the organiser applies to KGM via e-Devlet (Türkiye's e-government portal). The fee applied by KGM from 1 January 2026 is TRY 18,813.80 per permit.
- Transport: The route, time and escort conditions in the permit are complied with.
According to the regulation, for loads that are indivisible only in terms of their dimensions, more than one piece of the same load may be loaded provided the total weight limits are not exceeded.
What is the penalty for overloading?
Article 65 of Highway Traffic Law No. 2918 (Karayolları Trafik Kanunu), as amended by Law No. 7574 in February 2026, provides for separate fines for the operator and the consignor where the maximum laden weight is exceeded: starting at TRY 10,000 for overloading of up to 10% and rising to TRY 60,000 above 25%. If the excess exceeds 20%, the vehicle cannot continue its journey until the load is reduced. The fine for carrying a load subject to a permit without one is TRY 60,000.
How does Voltim Global support this?
In heavy cargo transport, Voltim Global plans the axle distribution together with the vehicle selection and handles the KGM application; on one shipment on the Voronezh–Mersin route, the permit process was completed in one day.