Semi-trailer truckUnited Kingdom
Traffic rules
United Kingdom
85. Semi-trailer truck
A semi-trailer truck is a combination consisting of a road tractor and a semi-trailer used primarily for transporting goods. The semi-trailer is coupled to the tractor so that a significant part of its weight is supported by the tractor rather than entirely by its own wheels.
Semi-trailer trucks are commonly used for long-distance freight transport and may carry containers, refrigerated goods, liquids, bulk materials or other cargo. Special rules can apply concerning driving licences, maximum dimensions and masses, speed limits, lane use, overtaking, loading and driving and rest periods.
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What is a semi-trailer truck?
A semi-trailer truck consists of a powered road tractor coupled to a semi-trailer primarily used to transport goods.
What is a semi-trailer?
A semi-trailer is a trailer designed so that part of the trailer and a significant part of its load are supported by the towing tractor.
What is the difference between a semi-trailer and an ordinary trailer?
An ordinary trailer generally supports its own weight through its axles, while a semi-trailer transfers a substantial vertical load to the tractor through its coupling.
How is a semi-trailer connected to the tractor?
The semi-trailer is normally connected through a kingpin and fifth-wheel coupling mounted behind the tractor cab.
Why are semi-trailer trucks called articulated vehicles?
The tractor and semi-trailer are connected by a pivoting coupling, allowing the two parts to turn relative to each other when the combination changes direction.
Do you need a special licence to drive a semi-trailer truck?
Yes. Heavy articulated trucks normally require a heavy-goods-vehicle licence that also authorises the driver to tow a heavy trailer or semi-trailer. The precise licence categories differ between countries.
Do semi-trailer trucks have lower speed limits?
They often do. Many countries impose vehicle-specific maximum speeds on heavy goods vehicles, particularly on motorways and other high-speed roads.
Why do semi-trailer trucks need more space to turn?
The semi-trailer's rear wheels follow a tighter path than the tractor's front wheels. Drivers therefore need additional space when turning, particularly at narrow intersections.
Why should you leave extra distance behind a semi-trailer truck?
Large trucks can restrict your view of traffic ahead and require considerable stopping distance. Keeping an appropriate following distance improves visibility and reaction time.
Why should you take care when driving beside a semi-trailer truck?
Large trucks have substantial blind spots around the cab and trailer. Avoid remaining beside the vehicle unnecessarily and be particularly careful when the truck is turning or changing lane.
