There’s several functions, one is literally just weighing trucks to make sure they aren’t overweight on one axle or overall.
They also inpsect trucks and drivers logs (record of time driving/on duty) at these stations.
You can get a system that lets you bypass the scales based on the safety record of your carrier. It’s either built into a tablet on the dash or you have a little ez pass type thing but it flashes and beeps to let you know if you have to go in or not. The idea being very safe carriers don’t require heavy enforcement and it’s better to only inspect them on occasion and focus on the shadier carriers.
Also they aren’t always open. In which case you can bypass them, also if traffic is backed up past the exit lane end you can bypass the scales legally.
Some have a weigh in motion (exactly what it sounds like) system that then directs you to pull in for a more accurate reading or bypass.
Different states all do it slightly differently and different stations within those states will be different based on how much traffic they need to handle.
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