Graham Black explores the tricky question of using and towing construction equipment on the road 

Towing and using construction equipment on the public highway in Great Britain is fraught with dangers – to other road users and to the drivers’ and business owners’ licences, bank balance and liberty. This guide is intended to highlight the main areas of concern, but, as always, if in doubt consult a legal professional.


If you are reading this the chances are that you are not a member of the agricultural, horticultural or forestry community, but principally involved in the construction industry. In this case, no matter what you think about the law, what you have been told down the pub, what you have read on social media, or what your high-speed tractor is capable of, the use of an agricultural tractor and trailer for transporting construction equipment on the public highway is, in the vast majority of cases, illegal.

Only those directly associated with the aforementioned industries conducting work in relation to this type of business have the right to use a tractor for such  purposes. For those looking at ways to get around this simple fact, yes there is the possibility of registering a tractor as either a locomotive or as a motor tractor. But in these cases it cannot be used with any form of semi-trailer (typically a low-loader) and, in any case, cannot be used for the transport of goods other than fuel, tools etc. for its own use. Then there are those that think that including a tractor on the firm’s Operator Licence, installing a tachograph and using non-rebated diesel is allowable; but no such modern tractor can be legally registered as an HGV (and therefore taxed as an HGV), as it is not certified to on-road emissions standards. The harsh fact of life is if you have chosen to use a tractor because it is cheaper than running an HGV, you will probably be breaking a number of laws. If you need more off-road mobility than a standard truck provides, use either a non-agricultural version of a Unimog or a special high-mobility version of a truck.


When using construction equipment on the road, the same general principle applies. If you are using an item of plant on the public highway because it is cheaper than using an HGV (either to transport it or to carry goods), you are likely to be breaking the law. Before we look at the exemptions, it is important to recognise what constitutes a public highway. In general, it does not matter who owns the land, who maintains it or what surface it has. If the public has a reasonable expectation of a right of way, it is likely to be deemed as the public highway. This can catch out the unwary, for xample using an item of unroadworthy kit on an open stretch of road on site leading to a show house on a new residential development.

It is also important to  recognise what does not constitute an open public highway. As far as the construction industry is concerned this is mainly a stretch of road covered by a pre-planned temporary closure order, or an emergency closure to repair utilities and the like. Again, this can catch out the unwary, for example unloading an unroadworthy machine outside of nthe closed area and driving it a short distance to the worksite. Unless cordoned off and included in the temporary closure, the public highway also includes verges, footpaths and laybys. Certain types of construction equipment can be used on the road, the general principle being that the driver should hold an appropriate driving licence and the vehicle should be registered (with a number plate), taxed and insured for on-road third party risks. It also has to comply with other road laws, which include lighting, horns and mirrors depending upon the machine and the circumstances of its use. To be frank, this is such a minefield that there is very little point trying to second-guess the law. My advice is to go for the safe and easy option of fitting or ordering the machine with the manufacturer’s road kit. If the manufacturer does not offer a road kit the chances are that it is not possible to legally use it on the road.

The machine’s axle weight limits should also be observed; the vehicle should not emit excess black smoke and generally be in good condition, particularly its brakes. One of the key bits of jargon as we delve further into this subject is the Maximum Authorised Mass (MAM) of the vehicle, which for all practical purposes is the  maximum allowed gross vehicle weight (GVW), not its actual weight. As far as driving licences are concerned, the vast majority of cases of operating construction  equipment on the road are covered by a normal Cat B car licence. There is a long list of exceptions that allow vehicles with a MAM of over 3.5 tonnes to be driven without an HGV (LGV) licence. However, the driver has to be 18 to drive such a vehicle with a MAM of between 3.5 and 7.5 tonnes, and over 21 to drive a vehicle with a MAM of over 7.5 tonnes. I appreciate that this later age limit has disappeared for HGVs, but my understanding is that it still applies to construction equipment. There are many special vehicle types with a MAM of over 3.5 tonnes that can be driven on a normal car licence, including those described as Road Construction Vehicles and Engineering Plant. Despite the title of these categories, the vehicles that fall within this description are not necessarily construction equipment, but vehicles used by specialist contractors, for example road marking trucks. The two subcategories that are of primary interest to EARTHMOVERS readers are works trucks and digging machines.


The definition covers a dump truck working in connection with and in the immediate vicinity of road works. There is no legal definition of what constitutes the  immediate vicinity’, but it is considered very unlikely if the courts would accept that this is more than 1000 yards. In any case this limit is important, as it is virtually the same as the 1km limit of the vicinity of road works that allows the dumper to use rebated diesel. Providing that the design speed of the dumper is less than 40kph, works trucks are exempt from the requirement to fit tachographs and do not need to be included on the firm’s Operator Licence.

Talking about the use of rebated (red or green) and non-rebated (white) diesel, one of the guiding principles is that a vehicle cannot be run on different fuels at different times. It is either run on rebated or non-rebated fuel all the time. This is to allow roadside checks to be made to ensure that rebated fuel concessions are not being broken. This definition of a works truck also applies to what the law describes as forklift trucks, which may also cover the use of some telehandlers. However, it probably does not cover the use of telehandlers equipped with access platforms, and those equipped with buckets are in danger of being regarded as digging machines (and therefore cannot carry a load on the road). Particularly with site dumpers, it is important to note that it is illegal to use these on the road if they are fitted with a green flashing beacon as part of the seat belt in use warning system. Green flashing lights on the road are reserved for medical staff. 


Typically cover wheeled excavators and backhoe loaders being driven to and from work sites. They are not allowed to carry any goods on the public highway – such as a load of hardcore in the bucket – although tools, attachments and fuel for the vehicle are allowed. Providing the vehicle is used within this scope it is exempt from operator licence and tachograph requirements and can use rebated fuel. If my statement on the use of agricultural tractors makes you shudder, be prepared for an even bigger shock when it comes to towing trailers on the public highway with construction equipment. The underlying issue is that the various laws covering the use of construction equipment on the road have not been updated for decades and are administered by a number of separate government departments.

The basic fact of life – as I found out when compiling this guide – is that no one organisation knows the full extent of the law regarding using construction equipment on the road. Until now, the consensus of opinion was that, as the likes of a wheeled excavator is driven on a car licence, those that hold a B+E category are entitled to tow a trailer with it. Those manufacturers and  contractors who take a conservative approach to such matters limit the trailer to a MAM of 3.5-tonnes, in-line with the regulations pertaining to a car. Some even took notice of the European-wide regulations that specifically limited those who passed their category E trailer test after 19 January 2013 to a 3.5-tonne trailer. The shocking piece of news is that this consensus of opinion is wrong. As I was compiling this guide, the  Vehicle Certification Agency (VCA) stated that the use of any earthmoving equipment to tow a trailer on the public highway is not permitted, even if it is being used to transport attachments. I understand that this is due to type approval regulations, as the VCA does not regard any type of trailer currently available for such applications being classified as engineering plant. 

This ruling is being challenged, principally by JCB. My view is that any trailer that could, in theory, be used for general transport of goods – even if it is not being used as such – is unlikely to fall within the scope of engineering plant. My strong advice is not to tow  a trailer behind any item of construction equipment on the public highway until the law is either further clarified or changed. While talking about the use of construction equipment on the road, a peculiarity of the law is weight estrictions on bridges and the like. Just like an HGV, digging  machines and works trucks are restricted not based on actual weight of the vehicle at the time, but their MAM. As for using tracked machines on the road, steering wheels are required on all vehicles used on the public highway, so mini-excavators and the like cannot normally be used on an open public highway. 


Before discussing towing items of compact plant behind vans and 4x4s, there is another bit of legal jargon to contend with: Gross Train Weight (GTW), sometimes referred to as Gross Combination Weight (GCW). This is the total allowable gross weight of the combination of the vehicle and trailer, again not its actual weight. Trailers with a MAM of up to 750kg present few problems for those that hold a category B driving license.  It may be possible to tow a slightly larger capacity trailer on a category B licence, but the rules are complex. The GTW must be less than 3.5 tonnes and the MAM of the trailer should not exceed the unladen weight of the towing vehicle. Putting the subject of such small trailers to one side, in this section we focus on trailers with a MAM of between 750kg and 3.5 tonnes behind a vehicle with a MAM of less than 3.5 tonnes, typically a wide variety 4x4s. The first issue to address is if the driver is legally allowed to tow such a trailer. Those that passed their car driving test before 1 January 1997 should be fine, as their licence will include the B+E category. Those that passed their test after this date will have to take a separate trailer towing test.

In general, the advice is not to tow a weight greater than the towing vehicle, indeed many would suggest that the loaded trailer should not weigh more than 85% of the towing vehicle. In any case, it is understood that those that passed their car test after 1 Jan 1997 are not allowed to tow a trailer with a greater weight than the towing vehicle. For drivers who passed their test before this date, although it is not strictly illegal to tow 3.5 tonnes behind a two tonne 4x4, in the event of a serious accident, good luck trying to explain to the authorities that this is an inherently safe practice.

A top tip is to use what the law describes as a dual-purpose vehicle for towing. As such vehicles are automatically exempt from any operator licence requirements. In the majority of guides to this topic the example of a Land Rover is provided to illustrate what a dual purpose vehicles is. This is somewhat misleading, as some of their larger products are above the unladen weight threshold of  040kg. Providing a vehicle is below this weight and is designed or adapted to carry both goods and passengers, and has either permanent or selectable four-wheel  drive, it counts as a dual-purpose vehicle for the purpose of an exclusion from operator licence requirements. If it is not a 4WD, there is a complicated set of  equations, including the measurement of the location of the second row of transverse seats and the actual area of glass in the back of the vehicle. This basically covers large estate cars, but obviously excludes vans. Running a vehicle that is within the scope of operator licences is an expensive and time-consuming affair.


Now we come to the tricky subject of tachographs. Any combination with a GTW of over 3.5 tonnes used for commercial purposes is assumed to come within the  scope of the EU working time directive, which normally requires a digital  tachograph to be fitted to record the driver’s working hours. Remember, even if it doesn’t, the driver will probably still have to record his hours to satisfy the UK working hours regulations. Those with a direct involvement with utility companies (see panel) may be excluded from the tachograph and other regulations, but for the vast majority it is important to ensure that the towing operation is carried out under the main exemption from the tachograph rules. These are that machinery, equipment and materials carried in the trailer are for the driver’s use in the course of their work, it is within a 100km radius of their base and driving the vehicle does not constitute the driver’s main activity. One of the key factors when towing is to ensure that that  vehicle, trailer, nose and axle weight limits are strictly observed. The place to  start will usually be under the vehicle’s bonnet in the form of a metal plate providing a  number of figures. This may include the total weight that can be carried by each of its axles, typically it is the mass on the rear axle that causes an issue. Be careful  not to overload this axle when towing, due to either goods being carried in the vehicle or the hitch carrying too much noseweight from the trailer. 

The load on the trailer should be positioned so that the vast majority of weight is carried by its axles. Too much weight to the rear is a recipe for disaster and the vehicle manufacturer’s recommended noseweight on the hitch can be surprisingly small, below 100kg in some cases. Obviously, ensure that the load is securely fastened to the trailer. The other two weights on the plate are usually where folks are caught out on roadside checks. The lower number is the Maximum Authorised Mass (MAM) or Gross Vehicle Weight (GVW) of the vehicle. The higher figure is the Gross Train Weight (GTW) or Gross Combination Weight (GCW). To obtain the maximum allowable gross weight of the trailer for that particular vehicle, subtract its Maximum Authorised Mass from the its Gross Train Weight. However, if the towing vehicle is not fully loaded, any spare capacity can be used by the trailer, up to its MAM. If stopped by the authorities, they would probably also want to see an official mark on the hitch indicating that it is capable of handling such a trailer. Simply because a vehicle manufacturer specifies a high towing capacity, this does not necessarily mean that the supplied standard hitch is designed for this weight. 


Many in the construction industry refuse to accept what the law is, particularly using an agricultural tractor to transport construction equipment and respecting the weight limits when using a 4x4 to tow a trailer. I suspect the principal reason for this is a desire save money and paperwork. Others genuinely do not know what the law is and I trust that this guide will help them through the somewhat complex process of legally using or towing construction equipment on the road. But this document is exactly that – a guide – and I cannot stress enough the importance of obtaining proper legal advice that takes into consideration individual circumstances.

Earthmovers July 2017 issue