Out-of-gauge (oversize) cargo is an indivisible load that, once loaded onto a vehicle, exceeds at least one of the limits in Article 128 of the Turkish Road Traffic Regulation (Karayolları Trafik Yönetmeliği): 2.55 m width, 4.00 m height, 16.50 m length for a tractor and semi-trailer, or 40 tonnes gross weight. Such cargo may only be moved with a special permit from the General Directorate of Highways (KGM), on a designated route and under set conditions.
What does the gauge concept measure?
Gauge refers to the external dimensions a vehicle is permitted to have so that it can travel safely on the road, whether loaded or empty. Width, height and length are measured for the vehicle and the load together. On the weight side, not only the gross weight but also the load each axle transfers to the road is limited. Even if the load itself is small, the transport is considered out of gauge if the vehicle combination exceeds these dimensions.
| Criterion | Legal limit (KTY Art. 128) | What it means in practice |
|---|---|---|
| Width | 2.55 m (2.60 m for refrigerated bodies) | The widest vehicle that stays within a standard lane |
| Height | 4.00 m | Clearance under overpasses, tunnels and power lines |
| Length | 16.50 m (tractor + semi-trailer), 18.75 m (truck + trailer) | Turning radius at junctions and bends |
| Gross weight | 40 tonnes (combinations with 5 or more axles) | Capacity of bridges and road structures |
| Axle weight | 10 tonnes non-driven, 11.5 tonnes driven single axle | Load-bearing capacity of asphalt and engineering structures |
For the detailed table, see the entry on legal dimension limits on the road.
Why is it treated as a separate type of transport?
The regulation allows cargo exceeding the limits to be transported only when the load cannot be divided and there is no alternative to road transport. That is why the indivisible load requirement is the foundation of the permit process. If the load can be dismantled to bring it within legal dimensions, shipment in parts is required instead of a special permit.
Obtaining the permit does not end the job. An out-of-gauge transport requires the following additional elements:
- route, time and speed conditions set by KGM,
- a lowbed, extendable trailer or modular trailer suited to the size of the load,
- escort vehicles depending on width and length, and police escort where needed,
- advance checks of bridges, culverts, overpasses and power lines.
Which loads are out of gauge?
The main equipment of energy and industrial projects falls into this class. Power transformers, industrial boilers, petrochemical columns, wind turbine blades, large construction machinery and bridge girders are typical examples. Nuclear power plant equipment is an extreme example: the reactor pressure vessel manufactured for Unit 3 of Akkuyu NPP weighs about 350 tonnes and is 11.45 m long, while each of the VVER-1200 steam generators delivered to the same plant weighs 340–355 tonnes and is 14–15 m long.
Where do road, sea and site differ?
On the road, the decisive factor is the KGM permit. At sea, the same load can be carried in a flat rack or open top container, as breakbulk or on a RoRo vessel; here the limits are set by the ship's hold, ramp capacity and port cranes (see shipping out-of-gauge cargo by sea). At the project site, the load is put in place using SPMTs, jacking-skidding and a crane lifting plan.
Common mistakes
- Giving the dimensions of the load without packaging; crates, skids and lashing elements can add several centimetres to the width.
- Calculating the height without adding the trailer deck.
- Seeing that gross weight is below the limit and not checking axle loads.
- Committing to a delivery date before a route survey has been carried out.
How does Voltim Global help?
In out-of-gauge and heavy cargo transport, Voltim Global plans the permit, vehicle selection and escort arrangements together. For example, on the Voronezh–Mersin shipment the KGM special permit was obtained within one day of the application. The step-by-step process is described in the guide to out-of-gauge cargo transport.