Weights and Dimensions

The maximum permissible weights and dimensions of goods vehicles in the UK have traditionally been set out in the Road Vehicles (Construction and Use) Regulations 1986. The regulations specific to the maximum permissible weights (C&U) can be found under regulations 75, 77 and 79 of the act. However, EU legislation in the form of directives have been incorporated into these regulations with EC directives setting common standards specific to International Transport (directive 85/3) and Domestic Transport operations (directive 96/53).

On 1 January 1999 directive, 96/53 regarding weight limits was made law as part of the Road Vehicles (Authorised Weight) Regulations 1998 and was not included within the Construction and Use Regulations as a further amendment.

The Authorised Weight Regulations run in parallel with C&U regs, which results in operators opting to choose to comply with either set of regulations. However, you cannot comply with a combination of the two regulations.

Vehicle weights
The information laid out in the tables below show both Construction and Use (C&U) and Authorised Weight (AW) rules. However, please be aware, it is not possible to operate to the weight limits in the new regulations whilst using the axle spacings specified in the C&U regulations.

RFS means that road friendly suspension is fitted on the drive axle. As an alternative each drive axle weight may not exceed 9,500kg (but see ** and *** below). Twin tyres must also be fitted.

* 38,000kg is permitted where the combination consists of a two-axle tractor unit and a two axle semi-trailer, the weight of the tractor unit does not exceed 18,000kg, the weight of the semi- trailer does not exceed 20,000kg for which an axle spacing of at least 1.8m is required and drive axle is fitted with twin tyres and road friendly suspension.

** Operation over 38,000kg is restricted to certain road-rail movements, subject to conditions – see below.

*** Operation over 40,000kg requires the axle weight of each drive axle not to exceed 10,500kg, the drive axle(s) to have road friendly suspension OR not to exceed 8,500kg axle weight, the trailer to have road friendly suspension and each part of the vehicle combination to have three axles. (Operation over 41,000kg requires, in addition, the use of an engine complying with the Euro 2 standard (or better) or a gas engine.)

44 tonnes operation

From March 1994, the construction and use regulations permitted six axle articulated and drawbar combinations to run at up to 44 tonnes. However, this is subject to conditions, on certain road-rail movements of which the following key points are applicable:

• the vehicle must be moving a loading unit to or from a railhead before or after a rail movement
• no goods can be added or removed during the journey
• a loading unit means a bi-modal vehicle (a semi-trailer which can form part of a train); a “piggyback” road-rail semi-trailer; or a container or swap body at least 6.l metres (20ft) long
• the vehicle combination must have twin tyres on every non-steering drive axle. Road friendly suspension must be fitted on each drive axle OR each drive axle weight must not exceed 8,500kg
• documents must be carried providing specified details of the railhead and movement

With effect from 1 January 1999, part of the EU weights rules (directive 96/53) was extended to cover five axled (3+2) articulated vehicles operating at 44 tonne operation. However, the provision is limited to a vehicle moving a 40ft ISO container to or from a railhead as part of an international railroad movement, and only applies where the through international movement is by rail. It must be noted here, that in all cases the appropriate documents must be carried.

With the introduction of 44 tonne vehicle use, having been permitted since 1 February 2001, in all instances, the vehicle being operated must comply with the requirements laid down in the table above.

Axle Weight Limits

The following table lays out the axle weight limits by Construction & Use and Authorised Weight limits.

** Twin tyres must have the centres of their areas of contact with the road at least 300mm apart. Wide tyres must be at least 300mm wide.

Bogie Weights – C&U

Two closely spaced axles (see Fig 1. and Fig 2. below)
The weight that two “closely spaced” axles (two axles spaced at least 1.02 metres but not more than 2.5 metres apart) on a motor vehicle, drawbar trailer or semi-trailer, may impose on the road depends on two factors:

1. the distance that the two axles are apart, and
2. the relevant plated weight of each axle

The regulations provide a scale dependent on these distances and plated weights.

Three closely spaced axles (see Fig 3. and Fig 4. below)
Where three “closely spaced” axles are concerned, the weight that a motor vehicle, drawbar trailer or semi-trailer may impose upon the road surface will vary dependent upon the axle spacing between any adjoining axles. However, this will apply only where;

• the outermost axles are spaced not more than 3.25 metres apart, and
• no axle has a plated weight exceeding 7,500kg mpw, and
• the total Maximum weight does not exceed 22,500kg

Semi-trailer limits were amended on 1 January 1989, thus allowing each axle to be plated at 8,000kg. As a result of these amendments, the total weight of a tri-axle semi-trailer can be plated at 24,000kg, provided the following conditions are met:

• each axle must be fitted with air or fluid suspension devices (meeting set conditions);
• the distance between any two adjoining axles must be at least 1.3 metres; and
• the weight imposed by any one of the axles does not vary from that imposed by any other axle by more than 500kg.

Bogie Weights – AW
Because of the introduction of the Road Vehicles (Authorised Weight) Regulations 1998, requirements became simplified with changes taking effect from 1 January 1999.

Weight by reference to axle spacing
There are many tables that detail the regulatory requirements within the C&U regs, in an effort to simplify matters, the DfT therefore introduced a simple calculation as shown in the table below.
By using this calculation, it is now straightforward to calculate the weight at which a vehicle will be allowed to operate under the authorised weight regulations. It must be noted however, that the factor will vary according to the number of axles, as follows:

• Rigid Vehicles – the distance between the front and rear axles (metres) multiplied by the factor in the table which applies to the number of axles
• Articulated vehicles – the distance between the semi-trailer kingpin and centre line of the rearmost axle (metres).

NB. The calculated figure should be rounded up to the nearest 10kg if the resultant calculated number is less than the maximum authorised weight.

The maximum allowable weight in the UK is now the lower of the maximum authorised weight as defined in the regulations and that determined by applying the multiplier to the vehicle wheelbase. Therefore, if the calculated figure is less than the maximum authorised weight in the UK then the vehicle is restricted to this lower figure. If this figure is greater than the maximum authorised weight in the UK, the vehicle may only operate at the maximum authorised weight in the UK. (See below)

Examples
A two axle rigid motor vehicle with a 2.5 metre axle spread would be limited to 2.5 x 6,000 = 15,000kg. A four-axle rigid motor vehicle with a 6.5-metre axle spread would be limited to 6.5 x 5,000 = 32,500kg, which is above the maximum authorised weight. The maximum authorised weight of 32,000kg therefore applies.

An articulated vehicle with a distance of 7.28 metres between the kingpin and centre line of the rearmost axle would be limited to 7.28 x 5,500 = 40,040kg, therefore the maximum authorised weight of 40,000kg applies. However, if the vehicle is of five axle (3 + 2) configuration operating on an international road/rail movement and carrying a 40′ ISO container (with all relevant documentation), then the vehicle can carry the full 40,040kg.