Rules in detail: Speed classes and vehicle size

Buses and minibuses carrying people for reward

What the rule says. A speed limit of 100 kilometres per hour applies to a bus and to a minibus that carry people for reward. These two vehicle types have this limit of their own.

Why it matters. Public passenger vehicles carry many people, so the manual gives them a fixed limit of their own.

In practice. You are driving a minibus taxi on a freeway where the general limit is 120 kilometres per hour. Your own limit is still 100 kilometres per hour, because it is set for your vehicle type. On an open road outside town the general limit is also 100 kilometres per hour, so the two limits are the same there.

Key idea: Buses and minibuses carrying people for reward: 100 km/h.

Heavy goods vehicles and combinations

What the rule says. A speed limit of 80 kilometres per hour applies to four kinds of vehicle. First, a goods vehicle with a GVM of more than 9 000 kilograms. Second, a goods vehicle that draws one or two trailers, where the GVM of the goods vehicle plus the trailer or trailers together is more than 9 000 kilograms. Third, an articulated motor vehicle whose truck-tractor has a gross combination mass of more than 9 000 kilograms. Fourth, any breakdown vehicle that is towing another vehicle.

Why it matters. The limit follows the mass of the vehicle or combination, not the road you are on.

In practice. You drive a goods vehicle with a GVM of 12 000 kilograms on a freeway. The freeway limit is higher, but you must stay at 80 kilometres per hour. A tow truck that has a car hooked up is also held to 80.

Key idea: Over 9 000 kg, or a breakdown vehicle towing: 80 km/h.

Overall length of vehicles

What the rule says. The restricted overall lengths are: a trailer that is not a semi-trailer and has a GVM of less than 12 000 kilograms, 8 metres; a trailer that is not a semi-trailer and has a GVM of more than 12 000 kilograms, 12,5 metres; an articulated motor vehicle, 18,5 metres; a bus-train, 22 metres; any combination of motor vehicles, 22 metres; and any other vehicle, 12,5 metres.

Why it matters. Different vehicle types are allowed different lengths, so you must know which category yours falls in.

In practice. A single rigid truck that is not a trailer, articulated vehicle or bus-train measures 13 metres. It is over the 12,5 metre limit for any other vehicle. An articulated vehicle measuring 19 metres is over its own 18,5 metre limit.

Key idea: Remember 8, 12,5, 18,5 and 22 metres.

Overall height of vehicles

What the rule says. A motor vehicle may not be used on a public road together with any load on it if its overall height is more than a set figure. For a double-deck bus the limit is 4,65 metres. For any other motor vehicle the limit is 4,3 metres. The height is measured with the load on the vehicle.

Why it matters. A load adds to the height, so a vehicle that is legal when empty may be illegal when loaded.

In practice. A truck with its load stands 4,5 metres high. It is over the 4,3 metre limit, so the load must be lowered. A double-deck bus 4,5 metres high is within its 4,65 metre limit.

Key idea: Double-deck bus 4,65 m; every other motor vehicle 4,3 m, load included.

Overall width of vehicles

What the rule says. A goods vehicle with a gross vehicle mass of 12 000 kilograms or more may not be used on a public road if its overall width is more than 2,6 metres. Any other vehicle may not be used if its overall width is more than 2,5 metres.

Why it matters. A fixed width limit keeps vehicles inside their own part of the road.

In practice. A light motor vehicle with its load is 2,55 metres wide. It is over the 2,5 metre limit. A goods vehicle with a GVM of 14 000 kilograms and a width of 2,55 metres is allowed, because its limit is 2,6 metres.

Key idea: Goods vehicle of 12 000 kg GVM or more: 2,6 m. Other vehicles: 2,5 m.

Quick recap

• Buses and minibuses carrying people for reward: 100 km/h
• Goods vehicle over 9 000 kg GVM: 80 km/h
• Breakdown vehicle towing another vehicle: 80 km/h
• Length limits: 8 m, 12,5 m, 18,5 m, 22 m depending on type
• Height: 4,3 m, or 4,65 m for a double-deck bus, with the load
• Width: 2,5 m, or 2,6 m for a goods vehicle of 12 000 kg GVM or more