Weigh-in-Motion (WIM): A Key Technology for Protecting Road Infrastructure
Weigh-in-Motion (WIM) measures axle loads and gross vehicle weights of commercial vehicles while they are in motion, even at highway speeds. This makes it possible to detect overloaded vehicles at an early stage and direct them to targeted inspections without unnecessarily disrupting traffic flow. As a result, WIM makes an important contribution to protecting roads and bridges while supporting the efficient enforcement of weight regulations.
Why WIM matters
Roads are primarily affected by high axle loads. According to the so-called fourth-power rule, even minor overloads can lead to significantly greater pavement damage: an axle overload of 10% can cause approximately 46% more damage, while a 50% overload increases the impact to about five times the normal level. Bridges can also be subjected to greater stress as axle loads increase.
During a single pass, a WIM system can record axle loads, gross vehicle weight, axle spacing, speed, vehicle classification, and, when combined with license plate recognition, vehicle identification.
WIM and Static Weigh Stations
Static scales provide highly accurate measurements but require considerable time and personnel. High-speed WIM systems, by contrast, screen every passing vehicle under live traffic conditions, enabling risk-based preselection. Legally binding weight verification is then carried out through a subsequent static weighing process.
Depending on the application, different sensor technologies may be used. Piezoelectric sensors, quartz sensors, polymer sensors, bending plate systems, and load cell systems differ primarily in terms of accuracy, cost, installation effort, and long-term stability. For high-precision enforcement applications, quartz, bending plate, or load cell systems are often the preferred choice.
Bridge Weigh-in-Motion and Virtual Weigh Stations
With Bridge Weigh-in-Motion (B-WIM), sensors are installed on a bridge, allowing the bridge itself to serve as the measuring element. The advantages include minimal impact on the roadway, rapid installation, and the ability to generate additional data for bridge monitoring.
Rur-Scholle Süd: A Reference Project for a New Generation of Digital Weight Enforcement Systems
The Rur-Scholle Süd digital truck weight enforcement station on the A4 motorway between Aachen and Cologne represents a new generation of weight enforcement systems developed by Yunex Traffic in collaboration with Autobahn GmbH and the Federal Office for Logistics and Mobility (BALM). Unlike conventional WIM installations, the solution is not limited to measuring and preselecting overloaded vehicles. Instead, it combines WIM sensors, license plate recognition, image documentation, traffic management, a central operator terminal, and static follow-up weighing into a fully integrated process.
The digital truck weight enforcement station on the A4 simplifies the daily work of enforcement authorities.
Suspected violations are automatically detected, assessed, and safely guided into the inspection area. This transforms weight measurement into a seamless digital enforcement process that reduces the workload for operators, makes inspections more targeted, and minimizes disruption to traffic flow.
Yunex Traffic makes a Significant Contribution to WIM Technology
In this context, Yunex Traffic acts as a system integrator and provider of turnkey, customer-specific end-to-end solutions. The company combines WIM sensors, license plate recognition, image documentation, traffic management, a central operator terminal, and the integration of static follow-up weighing into a market-ready solution. The focus is not only on technical integration but also on delivering an end-to-end enforcement process tailored to customer requirements and real-world operational needs.
WIM data can be integrated into traffic management platforms, supporting not only weight enforcement but also bridge monitoring, infrastructure management, investment planning, and dynamic traffic control.
Weigh-in-Motion: Conclusion
Weigh-in-Motion delivers its greatest value as part of an integrated traffic and infrastructure management approach. The technology helps efficiently identify overloaded vehicles, reduce maintenance costs, improve the monitoring of bridges and roadways, and support investment decisions based on real-world load data.
By combining advanced sensing technology, intelligent data integration, and automated processes, WIM becomes a powerful tool for the cost-effective and sustainable preservation of road infrastructure.
