Moving an abnormal load is one of the most heavily regulated jobs in road transport, and for good reason. Oversized and overweight loads carry real risks to other road users, bridges and infrastructure, so the law sets out exactly how they must be planned, notified and moved. This guide explains what counts as an abnormal load, how the STGO categories work, and what training operators and drivers need.
What is an abnormal load?
An abnormal load is a vehicle or load that exceeds the normal legal limits for weight, width, length or axle loading. In broad terms a load becomes abnormal when it weighs more than 44,000kg, is wider than 2.9 metres, or is longer than the standard limits for an articulated vehicle. Because these movements fall outside the everyday Construction and Use rules, they are governed by separate regulations.
What does STGO mean?
STGO stands for Special Types General Order, the framework that allows abnormal loads to move on public roads under defined conditions. Vehicles operating under STGO are grouped into three categories based on their weight:
- Category 1 for the lightest abnormal loads, up to 46,000kg.
- Category 2 for loads up to 80,000kg.
- Category 3 for the heaviest movements, up to 150,000kg.
Each category carries its own speed limits, axle weight rules and notification requirements. Getting the category right is fundamental, because it determines who you must notify and how the movement must be carried out.
Notifying an abnormal load movement
Depending on the size and weight of the load, operators may need to notify the police, highway authorities and bridge owners before a movement, giving specified notice periods. Larger movements require more notice and more detailed route planning to avoid weak bridges and unsuitable roads. Failing to notify correctly is a common and costly mistake.
Why training matters
Planning and moving abnormal loads safely takes specialist knowledge that goes well beyond a standard HGV role. Drivers and transport office staff need to understand the categories, the notification process, route planning and load security. Proper training reduces the risk of prohibitions, delays and accidents, and it shows enforcement bodies that your operation takes its responsibilities seriously. Our Abnormal Load Transportation course covers the rules, categories and practical planning that operators and drivers need.
Frequently asked questions
Do I need a special licence to move an abnormal load?
You need the correct vocational driving licence for the vehicle, and the operation must comply with STGO and notification rules. Specialist training is strongly recommended, and often expected, even though it is separate from the driving licence itself.
What is the difference between STGO Category 2 and Category 3?
The categories are defined by maximum weight, with Category 2 covering loads up to 80,000kg and Category 3 up to 150,000kg. Higher categories have stricter speed, axle and notification requirements.
Who do I need to notify before moving an abnormal load?
Depending on the movement this can include the police, highway authorities and bridge or structure owners, each with their own notice period. The heavier and larger the load, the more notification is required.
Move special loads the right way
Abnormal load movements reward careful planning and punish shortcuts. The right training gives your team the knowledge to move heavy and oversized loads safely and legally.
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