Every time a truck leaves your yard, a 1986 statutory instrument travels with it. The Road Vehicles (Construction and Use) Regulations 1986 - C&U, in every enforcement letter you will ever receive - set the basic construction, equipment and use requirements for vehicles on GB roads, from brakes and tyres to dimensions and weights. Alongside them sit the Road Vehicles (Authorised Weight) Regulations 1998 (AWR), a parallel weight regime adopted from European rules. Most operators never read either, yet almost every roadside prohibition, weight prosecution and annual test standard traces back to them.
This guide explains how the two regimes fit together, what they demand in practice, and where operators most often trip.
C&U is the domestic rulebook: Statutory Instrument 1986 number 1078, amended many times. The AWR - Statutory Instrument 1998 number 3111 - brought in the maximum weight limits contained in European Directive 96/53/EC from 1 January 1999, and has itself been amended, including by the Authorised Weight (Amendment) Regulations of 2000 and 2001.
The critical point from the government’s HGV maximum weights guidance is that the Authorised Weight Regulations operate in parallel to the Construction and Use Regulations, but vehicles may only comply with one of the regulations - individual parts of the two regulations cannot be combined. You cannot take a C&U axle allowance and pair it with an AWR gross weight. The two regimes produce different headline figures for some configurations - a 2-axle rigid is 17,000kg under C&U but 18,000kg under AWR, for example - which is exactly why mixing them is prohibited.
The summary table in the guidance shows the shape of the limits:
Conditions stack on top. Operation above 38,000kg under C&U is restricted to combined transport operations. Above 40,000kg, the drive axle must not exceed 10,500kg with road friendly suspension - or the maximum axle weight must not exceed 8,500kg - each part of the combination must have 3 axles, the trailer must have road friendly suspension, and an engine of at least Euro 2 specification (or gas) is needed over 41,000kg. Road friendly suspension means a system where at least 75% of the spring effect comes from air or another compressible fluid, or an equivalent recognised under the directive.
The regulations set ceilings; your vehicle’s plates set its own limits within them. There are two kinds. Manufacturers’ plating - required, with limited exceptions, on all goods vehicles - displays the maker’s name and the maximum axle, gross and train weights the vehicle is designed to operate at. Ministry plating - the plate or plating certificate issued by DVSA to goods vehicles above 3,500kg gross - denotes the potential maximum legal weight of the vehicle; in GB the plate is usually carried in the cab of heavy goods vehicles or attached to the trailer chassis.
The maximum weights on either plate must not be exceeded. If you are unsure which plated weights apply, the guidance points you to the vehicle manufacturer or DVSA. And where a vehicle carries both a manufacturer’s plate and a Department for Transport plate, the DfT limits are the legal limits in England, Scotland and Wales.
C&U is the reason overloading is prosecuted the way it is. A vehicle is overloaded if it exceeds the weight limits displayed on either plate, and it can be overloaded on its axle or axles, its gross weight and its train weight - each a separate offence. The guidance’s example: a 3-axle articulated vehicle exceeding its plated weights on the 1st axle, 2nd axle and gross weight makes both the vehicle operator and driver liable to three separate offences from one load.
The consequences reach beyond the roadside fine. If gross or axle limits are found exceeded when a vehicle is weighed by DVSA, the police or trading standards officers, the company and/or driver risk prosecution - and an overloading conviction is one of the factors that can lead a Traffic Commissioner to take disciplinary action against the operator’s licence.
The same framework tells you where the exceptions live. Vehicles may operate above 44 tonnes only in exceptional circumstances - moving abnormal indivisible loads - under the Road Vehicles (Authorisation of Special Types) (General) Order 2003. Special types, not C&U, is also where longer semi-trailers gained their legal basis. If your work touches cranes, heavy haulage or LSTs, the special types order is the third regulation set to learn.
One honest quirk: the C&U regulations are not readily available on the internet in consolidated form and have been amended so many times that piecing together the latest version is onerous. The government’s own guidance suggests consolidated versions in city reference libraries and legal encyclopaedias, or buying the constituent statutory instruments. The AWR is available through legislation sources. For day-to-day operational purposes, the government’s summary guidance - maximum weights, overloading basics, the roadworthiness guide - translates the regulations into usable rules, and it is those operational summaries your maintenance and loading procedures should cite.
You do not need to quote statutory instrument numbers at your drivers. You do need loading procedures that respect plated limits, a clear view of which regime and conditions your combinations run under, and maintenance standards that keep every C&U-governed system - brakes, tyres, lights, steering - on the right side of a roadside inspection. The regulations are old; the enforcement is not.