Whether you find one at a depot, a legal roadside check, or weighing return loads, it’s helpful to understand the types of fixed and portable weighbridges.
For logistics managers, keeping an eye on the laden weight of every fleet vehicle is important in terms of compliance, fuel efficiency and, ultimately, profits. Government weigh stations are in position on the side of the UK’s main roads, and their high-tech equipment enables accurate and efficient axle weighing. In addition, some larger fleet operators invest in their own static and on-board portable weighing equipment – the latter of which is particularly useful for vehicles picking up regular return loads.
There are a number of types of weighing equipment involving different technology – in some cases not even requiring the vehicle to be stationary. They offer solutions for a wide range of vehicles and requirements, whether extreme accuracy or cost effectiveness is the more important factor.
Weight technology dynamic axle weighbridges are designed to counter the issue of vehicles with compensating suspension, which transfers the weight of the vehicle to different points of the axle when stopping and starting. When that happens it’s impossible to accurately measure the weight on each axle – the only way around this is to weigh the vehicle while it’s in motion (hence the term ‘dynamic axle’). While travelling at very low speeds (usually around 2.5mph) the vehicle is weighed without the occurrence of weight transfer.
While dynamic axle weighbridges are fairly common in law enforcement they’re also used by large cargo operators (such as supermarkets) with fleets of lorries carrying a wide range of different products, in order to ensure correct and consistent weight distribution.
For vehicles with two axles and no weight transference technology, static weighing is possible. A single axle static weighbridge system works by weighing each axle separately, giving a very accurate reading of weight distribution across the vehicle.
Most often used by companies operating vehicles up to 18 tonnes, static axle weighbridges are also used by public utilities (local authorities and contractors for waste removal) and in agriculture.
Static weighbridges can also be multi axle, where a larger platform is used to weigh groups or pairs of axles at the same time in order to determine the net weight of the vehicle. These types of weighbridges are useful to farmers, for example, who wish to measure the total weight of outgoing product, and for refuse authorities interested in the total weight of incoming product.
Full size weighbridges are used when the weight of the vehicle is used to calculate invoices for payment. As the name suggests, the vehicle is weighed as a whole (rather than per axle) and a gross and net measurement is calculated.
Full size devices cannot give an accurate measurement per axle, as they calculate the net weight by means of subtraction (per axle weight), so are therefore not as successful with vehicles that operate with weight transference.
Dynamic full weighbridges are a portable solution useful for hauliers whose business relies on return loads. This is because even if they are weighed at their home depot, when they pick up return loads from clients (many of whom may not have a weighbridge), they need to have accurate cargo weight information to ensure compliance and, perhaps, invoicing details. (Dynamic weighbridges have recently been approved by the NWML.)
Portable weighpads are another solution growing in popularity and can be kept in a vehicle to weigh loads on the road – again, particularly useful for drivers picking up return loads.
Compliance and Convenience
Ensuring compliance with legal weights is one of the most important aspects of a logistic manager’s role. Along with roadside law enforcement weighbridges, today, hi-tech on-board axle weighing equipment is becoming more and more common – making their job a whole lot easier.