Weigh stations are highway check points run by state departments of transportation. They check commercial trucks to ensure they do not exceed legal weight limits. Driving heavy trucks on public roads accelerates pavement damage, so states use scale houses to protect infrastructure. Drivers must pull into the scales when the roadside signs indicate they are open.
Modern weigh stations use weigh-in-motion scales that check trucks as they roll down the exit ramp. If the truck is under weight and has a clean safety record, a green light directs them back to the highway. If the truck is heavy or has active safety alerts, it must stop on the static scales for individual axle weighing and potential DOT safety inspections.