Loading Of Heavy Vehicles In South Africa
The Road Transport Management System
RTMS is an industry-led self-regulation scheme that encourages consignees, consignors and transport operators engaged in the road logistics value chain to implement a vehicle management system that preserves road infrastructure, improves road safety and increases the productivity of the logistics value chain. This scheme also supports the Department of Transport’s National Freight Logistics Strategy.
> Read the RTMS.
The Road Traffic Act, 1996 (Act No. 93 of 1996), and the Road Traffic Regulations made in terms of this Act determine the maximum mass limits of vehicles used on public roads. The Act also determines the powers of traffic officers regarding the enforcement of the mass limits. These mass restrictions and powers are discussed in this section.
THE MASS RESTRICTIONS
The permissible mass of vehicles is determined by the Road Traffic Regulations made in terms of the Road Traffic Act, 1996. The numbers of the relevant regulations are 234, 235, 236, 237, 238, 239, 240, 241, 242 and 243. In addition, section 69 to 73 and regulation 248 formulate a number of presumptions that are applicable to regulations 234 to 243. These regulations, which are quoted in Annexure A, are discussed below.
Regulation group 234 to 237
In these regulations it is explained which of the regulations 238 to 241 are applicable during determination of the permissible mass of an axle, an axle unit, a vehicle as a whole and combination of vehicles respectively. In order to determine the permissible mass of an axle, an axle unit, etc. all the appropriate regulations must be applied in respect of the vehicle concerned. The regulation, which prescribes the smallest permissible mass, is the one that determines the legal weight for an axle, axle unit, GVM or GCM for a particular vehicle.
In practice, this group of regulations (234 to 237) is used chiefly to explain the connection between the different regulations (238 to 241) to the court. It is not always immediately apparent to the court why, for example, regulation 240 is used as the basis of a charge while the same vehicle according to, for example, regulation 239 would have a greater permissible mass. For that reason the traffic officer and the public prosecutor should, in the formulation of the charge in the process of court, always refer to the specific regulation in the group 234 to 237 on the grounds of which the person is being charged, read together with the appropriate regulation in the group 238 to 241. The regulations in this group concern the following:
Axle and Axle unit mass:
- Regulation 234: Permissible maximum axle massload;
- Regulation 235: Permissible maximum axle unit mass load.
According to Regulation 234(2) or 235(2) the smallest permissible mass in terms of Reg 238, 239 or 240 is used to determine the maximum permissible axle mass or axle unit mass.
Vehicle and vehicle combination mass:
- Regulation 236: Permissible maximum vehicle mass;
- Regulation 237: Permissible maximum combination mass.
According to Regulation 236(2) or 237(2) the smallest permissible mass of the sum of permissible axle or axle unit mass, Regulation 239, Regulation 241 or 56 000 kg is taken to determine the maximum permissible vehicle or combination mass.
Regulation group 238 to 241
This group of regulations contains specific prescriptions on the maximum permissible masses of vehicles. Each of these regulations approaches the mass of a vehicle from a different viewpoint. Regulation 238 prescribes maximum masses according to the carrying capacity of the tyres of the vehicle. Regulation 239 is concerned with the manufacturer’s specification, that is, the maximum mass for which the vehicle itself was designed. Regulation 240 is chiefly concerned with the maximum mass that the road pavement (asphalt or concrete surface plus the underlying layers forming the structure of the road) can carry, while regulation 241 is concerned with the maximum mass that can be carried by bridges and structures on consecutive axles or groups of axles.
It is important to note that all these regulations are simultaneously applicable and that the one which prescribes the lowest mass for a particular vehicle is the one according to which it must be determined whether an offence has been committed. This approach may be explained by the following example: A vehicle with a gross vehicle mass of 10 000 kg will, according to the manufacturer’s specification (regulation 239), be permitted to carry a maximum load of approximately 5 000 kg on an axle, the tyre specification (regulation 238) permits a mass load of 8600 kg, while regulation 240 permits a maximum load of 9 000 kg. In this case the restriction of regulation 239 is the smallest and it is therefore applicable (compare with regulation 234). In the case of a larger vehicle, an axle may however, according to the manufacturer’s specification (regulation 239), carry for example 12 000 kg, the tyre specification (regulation 238) permits 10 600kg, while regulation 240 still prescribes a maximum load of 9 000 kg. In this case the restriction of regulation 240 is the smallest and is therefore applicable (compare once again with regulation 234).
COMMENT: The offence concerned is therefore determined by taking the smallest permissible mass that is prescribed by regulation 236. If it is found that a person contravenes more than one of the regulations, he can be charged on each contravention formulating alternative charges.
The regulations concerned are discussed individually in the remainder of this section.
- Regulation 238: The loading limit of tyres
Regulation 238 prescribes the mass restrictions that apply to the different vehicle tyre sizes and it also deals with tyre pressure. The aim of this regulation is to ensure safety.
The regulation refers to the standard Specification of the South African Bureau of Standards, SABS 1550: Motor vehicle wheels and rims: Dimensions and loads, Part 1 – 1992 (Government Notice No. 2006 of 17/07/92). The permissible mass, given the type of tyre and/or the tyre pressure, may be read from a table. Note that this regulation was amended in April 1999 to include the provision that: “ for the purposes of determining the pressure in a tyre, the temperature of the tyre shall be disregarded”.
It is recommended that the loading limit which is applicable to maximum tyre pressure should be accepted as the permissible loading limit at all times, which benefits the operator because it allows the maximum loading limit and the pressure of the tyre need consequently not be measured.
The tables below provide a number of loading limits with regard to the type of tyre at maximum tyre pressure, as it is applicable to certain of the more popular tyre sizes.
It should be mentioned that many vehicles still have the TREDCO sizes but these are being phased out gradually and replaced with the latest markings e.g. 148/152L
Examples of a passenger vehicle and truck tyre designation (Informations supplied by General Tyres)
Loading limit (Information supplied by General Tyres)
Loading limits for certain popular tyre sizes (from SABS 1550)
Maximum speed (Information supplied by General Tyres)
The provisions of regulation 238 entail that axles with single wheels are usually more easily overloaded than axles with double wheels. Special attention should therefore be given to all axles with single wheels. This includes the steering axle and the popular configuration where a three-axle unit with single wheels is used.
Wheels that are not fitted with pneumatic tyres are dealt with in regulation 243
- Regulation 239: The carrying capacity of the vehicle
Regulation 239 restricts the massload in accordance with the carrying capacity of the vehicle. This regulation, just like regulation 238, attempts to ensure road safety. Regulation 239 refers to three different matters that are all concerned with the carrying capacity the vehicle itself (engine, chassis and body):
- Regulation 239(1) prohibits the exceeding of the gross mass of an axle (GA), an axle unit (GAU), a vehicle as a whole (GVM) and a combination of vehicles (GCM). (“Gross” means, for all practical purposes, “as specified by the manufacturer”.)
- Regulation 239(2) determines the ratio between the mass of a vehicle and the engine power (net power).
The following may not be exceeded:
- For a tractor: Net power x 400
- For other vehicles: Net power x 240
Note: The use of a tractor to draw one or more semi-trailers is becoming increasingly prevalent Especially “Bell” tractors are often used as truck tractors. This is not permissible. This excludes the “BELL” vehicles used on construction sites for the transport of stone or gravel etc. (divisible load). Depending on the width these vehicles must be dealt with like any other vehicle since they have abnormalities.
Note must be taken of the definition of a tractor as contained in section 1 (lxxiv) of the Road Traffic Act.
“Tractor means a motor vehicle designed or adapted mainly for drawing other vehicles and not to carry any load thereon, but does not include a truck-tractor”.
Officers should not allow this practice. Prosecution must be instituted against persons who use tractors contrary to the provisions of the Road Traffic Act.
- Regulation 239(3) determines the ratio between the total mass of the vehicle and the mass on the driving axle(s).
The contents of the manufacturer’s specification on the vehicle plates is regulated by Regulation 245. Operators that affixed information plates to vehicles in terms of Regulation 245 before 1 March 1996, had a grace period until 1 July 1997 to reflect the information specified by Regulation 245. Operators who still have not affixed new information plates to their vehicles should be penalised. The old weights should be used in calculating permissible axle and axle unit mass load.
This is the only way to force operators who have not yet replaced old information plates to do so.
The total mass of the vehicle may not exceed the total axle mass of the driving axle or axles by more than five times (i.e. the total mass must be less than 5 times the mass of the driving axle(s)).
Regulation 239 is, in particular, concerning all the axles of smaller vehicles and the driving axle of larger vehicles, the restricting regulation.
- Regulation 240: The carrying capacity of the road
Regulation 240 restricts the massload on axles and axle units in accordance with the restricted carrying capacity of the road (i.e. pavement damage). The aim of this regulation is to protect roads.
The subsections of this regulation are discussed as follows:
Regulation 240(1) determines that no person may use a vehicle or a combination of vehicles (with pneumatic tyres) on public roads if –
- any wheel mass load exceeds 3 850 kg on a steering axle and 4 000 kg on non steering axles;
- the massload of a single axle with two or three wheels exceeds 7 700 kg on a steering axle and 8 000 on axles other than steering axles;
- the axle massload of a single axle with four wheels exceeds 10 200kg on a refuse removal vehicle, breakdown truck, bustrain or a bus or 9 000 kg on other vehicles not mentioned in sub paragraph (i) to (iv) of regulation 240 (I) (c);
- the axle massload of a two-axle unit with two or three wheels fitted per axle exceeds 15 400 kg on a steering axle and 16 000 kg on non-steering axles;
- the axle mass load of a two-axle unit with four wheels fitted per axle exceeds 20 400 kg on a refuse removal vehicle or a breakdown vehicle or 18 000 kg on other vehicles;
- the axle massload of a three-axle unit with three or more wheels fitted per axle exceeds 23 100 kg on a steering axle and 24 000 kg on axles other than steering axles;
- the axle mass load of a three or more axle unit with four wheels per axle exceeds 24 000 kg.
To summarise, the massloads on axles and axle units (except for two-axle units on refuse removing vehicles, breakdown vehicles and buses) are the following:
MASS LIMITS IN TERMS OF REGULATION 240
- Regulation 241: The carrying capacity of bridges (bridge formula)
Regulation 241 determines the total massload of groups of axles excluding the axle units covered by regulation 240(b). The regulation must restrict the total massload of vehicles to a level that corresponds with the carrying capacity of road bridges. The enforcement of this regulation is of crucial importance because the current legal vehicle massloads already overload approximately 15% of South Africa’s bridges.
The subsections of this regulation are discussed as follows:
- Regulation 241(1) determines that no person shall operate on a public road a vehicle or a combination of vehicles (with pneumatic tyres), if the total axle mass load of any group of axles of the vehicle or combination of vehicles exceeds the mass calculated according to the bridge formula. The bridge formula is as follows:
Permissible mass = (L x 2 100) + 18 000 kilogram
where L = the distance from the first axle of any axle or axle unit to the last axle of any consecutive axle or axle unit (in metres).
See Figure below:
- Regulation 241(2) determines the axle groups to which regulation 240(1) may be applied or may not be applied. The axle units covered by regulations 240(d),(e),(f) and (g) are specifically excluded from the bridge formula.
- Regulation 241(3) determines how the distance between the axle groups should be measured.
- The distance should be measured in metres and tenths of metre from the first axle of any group to the last axle of such a group.
- If the distance that is measured is not a full tenth of a metre, the reading should be rounded off to the next higher tenth of a metre. Thus if therefore, the distance is for example 8,53 m, it becomes 8,6 m; 9,11 m becomes 9,2 m etc.
- Measurements should be taken with a vehicle or combination of vehicles in a straight line and the vehicle or combination of vehicles should be measured on both sides. The longest side’s dimension should always be used for the calculation.
The practical execution of this measurement is discussed in section 4.4.4
WHEEL AND AXLE MASS-LOADS PERMITTED UNDER REGULATION 240
Warning: On axles and axle units with single tyres, the tyre rating is critical. Operators should ensure that the tyre rating is adequate to achieve these mass-loads.
Regulation 242: Distribution of the massload on the vehicle
This regulation determines the maximum permissible difference between the wheel massloads on the left and right-hand side of a vehicle and the ratio between the mass of the steering axle of a vehicle and the mass of the rest of the axles of such a vehicle or the so-called under-loading of the steering axle. It specifies a minimum mass on the steering axle as a percentage of the mass of all the axles of such a vehicle.
MINIMUM LOAD ON STEERING AXLE OR STEERING AXLE UNIT
Regulation 243: Vehicles fitted with tyres other than pneumatic tyres
This regulation determines the permissible axle massloads of vehicles that are not fitted with pneumatic tyres.
Sections 69 to 73 and Regulation 248: Presumptions
Sections 69 to 73 of the Road Traffic Act, 1996, and Regulation 248 contain a number of presumptions that somewhat facilitates the evidential process in court. This overrules the necessity for complicated technical evidence on the reliability of the readings mentioned in the process of court, unnecessary unless the defence shows on a balance of probability that the readings can possibly be unreliable. The presumptions also make it possible to determine the total mass of an axle unit, vehicle or combination of vehicles by adding together the masses of individual axles or axle units. The following presumptions have practical implications for law enforcement on the road:
- The presumption in regulation 248(3) determines that the distance measured with a view to prosecution under regulation 241 shall be regarded as correct unless proof can be supplied that the actual distance is greater than the alleged distance. This means that distance readings that are definitely longer than the actual distance are acceptable. For this reason the distance between the axles of an axle group may be determined by pressing the measuring tape on the centre of the hub of the first and last axle of the group that must be measured. Since the hub is normally sunk, the measuring tape will stretch around the edges of the wheel rim, with the result that the reading that is obtained will always be slightly longer than the actual distance and this benefits the operator of the vehicle. The centre of the hub is usually marked. If this is not the case, the hub may be measured and the centre may be marked.
- The presumption In regulation 248(4) implies that a small scale may be used to determine the total mass of an axle unit or vehicle since the masses of the axles or axle units may be added together to calculate the total mass.
Section 45, 49 and 51 of the Road Traffic Act: Responsibilities of the operator
The law makes provision that the operator of a vehicle can be charged. The driver of an overloaded vehicle is often charged as the accused. If this person is convicted, he will have to face a fine or jail sentence for an offence which has benefited the owner of the company and not the driver. Admissions of guilt and previous offences are often registered against the driver and not against the company that owns or operates the vehicle.
To curb this situation, the law provides for the accusation of the operator of a vehicle. Firstly the law defines who the operator of a vehicle is (Section 45 of the Road Traffic Act)
Section 45: Registration of operator
Subject to paragraph (b), the owner of a motor vehicle of a prescribed class is the operator thereof, and shall, upon licensing thereof, be registered as such in the prescribed manner and on the prescribed conditions.
Notwithstanding the provisions of paragraph (a), a person who is not a manager, employee or agent of the owner of a motor vehicle referred to in that paragraph and who enters into a written agreement providing that such motor vehicle may be operated by such person for any period, shall for the purposes of section 49 (c), (d), (e), ( f ) and (g) be deemed to be the operator thereof for that period.
Secondly the law states the duties of the operator of a vehicle. These duties include proper control over the driver of such motor vehicle to ensure the compliance by such driver with all the provisions of the act, which includes the loading of vehicles (Sect 49(c)(ii) and Sect 49(g)).
Furthermore, the law states in Section 51(1) that whenever a manager, agent or employee commits an act or fails to commit an act and it would have constituted an offence under the Road Traffic Act if the operator had committed the act or failed to commit it, then such operator shall be deemed himself to have committed or failed to commit such act and be liable to be sentenced and convicted in respect thereof unless he proves that he took all reasonable measures to prevent the offence.