Problematic Measurements at WIM Sites
The closer to a standard the vehicle passage driving through a high-speed Weigh-In-Motion station is, the higher the probability, the better is the probability of a perfect measurement. Sooner or later, some of the drivers of overloaded vehicles are going to realize this. Consequently, they will try to avoid being measured properly.
Driver Behavior and Evasion Techniques
The standard is passing through the WIM site at a constant speed of roughly 20 – 100 km/h, with all wheels crossing the sensors. Sometimes, drivers intentionally make abrupt changes in their vehicles’ speed or sudden changes in driving direction. With CAMEA WIM, an advanced validation is performed in order to avoid incorrect measurement. Such a record is tagged as invalid and the user of the system can act accordingly, e.g. stop and weigh the vehicle if the video documenting the situation implies that the driver’s behavior was motivated by avoiding being weighed.
- CAMEA WIM PERFORMS ADVANCED VALIDATION, AUTOMATICALLY TAGGING MANEUVERS INTENDED TO EVADE WEIGHING AS INVALID
Detection of Lane and Shoulder Evasion
Avoiding crossing the sensors by leaving the lane is common. Changing the lane to the opposite direction won’t help the driver if the lane is equipped with CAMEA WIM as well. The system is capable of weighing in both directions within one lane. Those driving on the shoulder may be limited in this behavior by installing the guardrail. However, that is not always possible due to safety reasons. A combination of more pressure sensors and/or 3D scanners can represent a solution to this problem.
Challenges of Variable Vehicle Speed
Driving slowly causes issues at high-speed weigh stations. These can be tackled by a specific sensor setup. The great advantage of the scalable CAMEA electronics is the sensor independence, allowing to combine high-speed and low-speed weighing.