The Special Types General Order (STGO) is UK legislation that allows certain vehicles to operate on public roads even when they exceed the normal construction, weight or dimensional limits set by standard road vehicle regulations.
STGO, formally the Road Vehicles (Authorisation of Special Types) (General) Order 2003, provides a legal framework for vehicles that cannot comply with conventional limits but still need to travel on the public highway, typically when transporting abnormal or indivisible loads.
What STGO allows
Under standard Construction and Use regulations, vehicles must comply with defined limits for weight, axle loadings, width and length. STGO allows specific exemptions from these limits, provided strict operating conditions are met.
These exemptions are controlled to ensure that road safety and infrastructure are protected. Conditions may include route planning, speed restrictions, and advance notification to authorities.
Recent updates to STGO (2023 amendment)
Amendments introduced in 2023 expanded the scope of STGO to include certain vehicle types that do not necessarily exceed traditional weight limits but still fall outside standard Construction and Use regulations.
This includes longer semi-trailers (LSTs), which may operate within normal weight limits but exceed standard length restrictions. As a result, they are authorised under STGO conditions rather than conventional vehicle regulations.
This reinforces that STGO is not limited to heavy or abnormal loads. It also applies to vehicles that differ from standard regulatory limits due to their design, dimensions or operating conditions.
STGO categories
STGO defines different operating categories based on vehicle weight and configuration. These categories determine the conditions under which a vehicle may operate.
- STGO Category 1: up to 50 tonnes gross vehicle weight, with defined axle load limits
- STGO Category 2: up to 80 tonnes gross vehicle weight
- STGO Category 3: up to 150 tonnes gross vehicle weight
Higher weight categories typically involve additional requirements such as stricter route planning and greater involvement from authorities.
Vehicles that operate under STGO
Vehicles operating under STGO are generally used for transporting loads that cannot be divided into smaller parts without excessive cost or risk, or where the vehicle itself exceeds standard regulatory limits.
- Heavy haulage vehicles transporting abnormal loads
- Low loaders and modular trailers carrying large machinery or infrastructure components
- Specialist engineering transport equipment
- Longer semi-trailers and other authorised specialist vehicle types
Operator responsibilities under STGO
Operators must comply with specific conditions depending on the STGO category and vehicle configuration.
- Adherence to defined gross weight and axle loading limits
- Advance notification of certain movements to highway and police authorities
- Use of warning signage, lighting and markings where required
- Careful route planning to avoid unsuitable bridges or infrastructure
Responsibility remains with the operator to ensure that each movement is compliant, safe and properly authorised.
Frequently Asked Questions
What does STGO stand for?
STGO stands for Special Types General Order. It refers to UK legislation that allows certain vehicles to operate outside normal construction, weight or dimensional limits under defined conditions.
Why do some vehicles operate under STGO?
Some loads or vehicle types cannot operate within standard regulatory limits. STGO provides a legal framework allowing these vehicles to use public roads while meeting specific safety and notification requirements.
Is STGO only used for abnormal loads?
No. STGO is commonly associated with abnormal loads, but it also applies to vehicles that exceed standard construction or dimensional limits, including certain modern trailer types such as longer semi-trailers.
Where can the STGO legislation be read?
The Road Vehicles (Authorisation of Special Types) (General) Order 2003 and its amendments are available on the official UK legislation website.
