Weigh-in-motion stations allow trucks to keep moving while being weighed. Older weigh stations require the trucks to stop. Section 614 of the Colorado Department of Transportation’s Standard Specifications outlines the requirements for the state’s weigh-in-motion stations. These weigh stations record individual data for a truck’s axle spacing, speed, license number, speed and class. The data is stored in the station’s memory and also printed from an external computer.

Components

In Colorado, each weigh-in-motion station must have two Class 1 piezoelectric axle sensors in each lane. Additionally, the stations must have a data storage device and wiring suitable for battery chargers, printers and modems that can transmit at a minimum of 56 kilobits/second.

Diagnostics

The state requires that weigh stations receive annual diagnostic tests to check the station’s performance. Engineers test at a minimum, the station’s remaining storage capacity, axle sensor performance, low battery power and telemetry errors.

Manuals and Software

Contractors responsible for designing and building the weigh stations are required to leave three sets of operator’s manuals for each piece of equipment relating to the weigh station. The maintenance manuals should include schematics, diagrams, a list of parts and the current price list for each part. The contractor should provide enough software to run on three different computers, and the software should be operable on a Windows operating system.

Weigh Limits

Colorado enforces a 16,000-pound weight limit on trucks and trailers when empty. When filled with passengers and cargo, trucks and trailers cannot exceed a certain weight when on state highways or the Interstate. Vehicles with three or more axles cannot exceed 54,000 pounds when filled on the highway or interstate. Trucks or trailers cannot exceed 85,000 pounds on the highway and 80,000 pounds on the interstate.