Those are to make sure the trucks aren’t overweight. Heavier trucks do more damage to the road and carry more momentum, meaning they take longer to stop, whether through braking or crashing. Overweight trucks will be fined.
Most of the time, the stations aren’t open. There’s lights to indicate when they are open. Skipping an open weigh station also carries a fine, regardless of whether the truck was overweight or not. Skipping the weigh station multiple times can also result in suspension of a CDL or even jail time.
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