Trucks and other transportation equipment in this section are limited to those that travel on public roadways. These vehicles have become larger over the years, as engines and systems have become available that provide power and torque levels that are much, much greater than in the past. One of the basic requirements for all these vehicles is that they do not exceed a maximum load weight for each tire that contacts the ground. This is done to prevent damage to roadways. There are minimum distances between these wheels as well, and this has resulted in multi wheel combinations.

Rules and regulations exist that specify what these limits are, and these rules and regulations are generally specific to a geographic area, such as s state, province, or country.

Special configuration of these vehicles also allows them to be used for special purposes. Examples of this are bed trucks and Texas rig-ups used in the oilpatch.



A combination of a standard trailer and a shorter pup trailer.



In the simplest terms a “B-Train” consists of two trailers linked together by a fifth wheel, and are up to 26 m (85 ft) long. The fifth wheel coupling is located at the rear of the lead, or first trailer and is mounted on a “tail” section commonly located immediately above the lead trailer axles. In North America this area of the lead trailer is often referred to as the “bridge”. The twin trailer assembly is hooked up to a tractor unit via the tractor unit’s fifth wheel in the customary manner.

The main advantage of the B-Train configuration is its inherent stability when compared to most other twin trailer combinations and it is this feature above all else that has ensured its continued development and global acceptance.



A lowboy is a semi-trailer with two drops in deck height, one right after the gooseneck and one right before the wheels. This allows the deck to be extremely low compared with other trailers. It offers the ability to carry legal loads up to 12 ft (3.66 m) tall, which other trailers cannot.

On Highway

Off Highway


Oilfield Bed Truck

A bed truck, also known as a rig-up truck, is a specialized truck used in oil rig installation and service. It can transport heavy loads over poor surfaces, and can self load and unload with a winch and a tail roll. The winch is used both for loading the truck and for hoisting loads at the work site.


Single Axle Trucks


Tandem Trucks


Super B


Super B Triple

Australia has the largest and heaviest road-legal vehicles in the world, with some configurations topping out at close to 200 tonnes. Triple road trains operate in western New South Wales, western Queensland, South Australia, Western Australia and the Northern Territory, with the last three states also allowing AB-Quads (3.5 trailers).
In Canada, triples may be up to 35 m (115 ft) in length when using A or C converters, or 38 m (125 ft) in B-train configuration and is only allowed in certain areas of western Canada.

In the United States, some states allow three trailers, although triples are usually restricted to less populous states such as Idaho, Oregon and Montana. Triples are used for long-distance less-than-truckload freight hauling, in which case the trailers are shorter than a typical single-unit trailer.

Photo: ODOT


Tractor & Wagon

A dump truck is a truck used for transporting loose material such as sand, gravel, or dirt for construction. A typical dump truck is equipped with a hydraulically operated open-box bed hinged at the rear, the front of which can be lifted up to allow the contents to be deposited on the ground behind the truck at the site of delivery.


Turnpike Double

In the Untied States, turnpike doubles are two 48-foot (14.6 m) trailers with a maximum weight up to 147,000 pounds (66.7 t).

In Canada, a turnpike double is two 53-foot trailers.


Heavy Haulers

A heavy hauler usually consists of flatbed trailer units with multiple wheels (which may be independently steerable), pulled by a heavy tractor unit. Several trailers might be towed by one or more tractor units. The ability to carry loads of 2000 tons is not unusual.