Tags – Weigh in Motion Systems
Weigh in motion (WIM) devices are designed to capture and record a vehicle’s axle weights and gross vehicle weights as they drive over a sensor.
Unlike static weigh stations, WIM systems do not need the vehicle to stop and take a reading, which makes them much more efficient at recording weights.
Instead, they measure the vehicle’s weight whilst it’s traveling at normal traffic speed and can be used for both private and public operations.
As such, WIM systems are usually installed on the road or a rail track to provide data from the traffic flow and the specific vehicle.
However, there are certain conditions that apply as these will have an impact on the quality and reliability of weight recordings.
Simply, WIM systems measure the axle loads of the vehicles and try to calculate the best possible estimate.
And, these systems have to perform unattended, under harsh traffic and environmental conditions, with no control over how the vehicle is moving, or the driver is behaving.
Road Applications
The Driver & Vehicle Standards Agency (DVSA) has many WIM systems and Automatic Number Plate Recognition (ANPR) cameras installed across the UK.
The main reason being, it helps them to win the battle against overloaded vehicles that pose a threat to other road users and cause damage to the road’s infrastructure.
And, a combination of these systems and cameras have now replaced traditional weight control systems to make it easier to track down the offending vehicles.
As such, induction loops and sensors made up of piezo-electric strips are embedded into the road’s surface to record the weight of a passing vehicle.
Then, ANPR cameras record the vehicle’s registration number.
Essentially, the way it works is the system recognises the vehicle and measures its speed and weight, then compares this with the information on the DVSA database.
And, if the vehicle is overloaded, the system sends an alert to the supervising officer who will then inform the nearest patrol car.
Then, the officers will stop the driver of the vehicle from carrying on with their journey and direct them to the closest control point; on average, 4 trucks an hour are pulled over.
On British roads, these scales are very accurate and in almost every instance, the overloaded vehicle is re-weighed on a set of axle pads, or weighbridge where the original recording from the WIM system is confirmed.
Consequently, the driver and the company they work for will be given a fine or penalty and asked to lighten their load before they can continue to travel to their destination.
Moreover, these systems can recognise vehicles from abroad too, even if their information is not in the DVSA database; around 50% of the overloaded vehicles stopped are from overseas.
Strengths of Weigh in Motion Systems
Here are some strengths of weigh in motion systems:
- Processing Rate: Heavy goods vehicles can be weighed as they travel at “normal” traffic speeds, which results in a larger number of counted vehicles in quicker time compared to static weight sites
- Safety: minimising static weight sites will decrease vehicle accumulation on roads leading to these stations
- Ongoing Data Processing: data can be processed continuous, which can eliminate data bias
- Cost Effective: more vehicles can be weighed at the same cost as a static weight site
- Dynamic Loading Data: these systems can record dynamic axle load information which can be significantly larger than static load information
Weaknesses of Weigh in Motion Systems
Here are some weaknesses of weigh in motion systems:
- Accuracy: these systems are less accurate that static scales where the environment is better controlled
- Reduced Data: static weight stations can collect data like fuel type, year model, origin, destination and loaded or unloaded status, whereas WIM systems cannot
- Susceptible to Damage: WIM systems are sensitive to electromagnetic disturbances from things like lightning strikes
For more information, please get in touch today.
In the meantime, check our Vehicle Weight Checking solutions.
You may also like: