Weigh station e-screening technology

Find out how we're using technology to improve commercial vehicle safety for more than 33,000 trucking companies with more than 245,000 transponder-equipped vehicles.

We are the lead Innovative Technology Deployment agency for the state. The Federal Motor Carrier Safety Administration created the program to use technology to improve commercial vehicle safety. Currently, our program serves over 33,000 trucking companies with more than 245,000 transponder-equipped vehicles.


  • Focus enforcement on high-risk carriers.
  • Improve safety and productivity of motor carriers, commercial vehicles, and their drivers.
  • Improve accuracy, integrity and verifiability of commercial vehicle information.
  • Improve efficiency and reduce administrative costs by electronically screening commercial vehicles.

There are currently 11 electronic screening
locations in Washington.


Electronic Screening

This technology is located at 11 weigh stations and 3 virtual weigh-in-motion sites in the state. The system incorporates electronic screening software with roadside equipment that examine vehicles for violations while in motion.

Roadside equipment

  • Weigh-in-Motion (WIM): Scales in the roadway that determine a vehicle’s size and weight.
  • Overheight Detector: A camera that determines a vehicle’s height.
  • Automatic Vehicle Identification (AVI): Identifies the vehicle by reading a transponder.
  • Automated License Plate Readers (ALPR): Identifies the vehicle by reading the license plate.
  • Changeable Message Signs (CMS): Allows for customized notifications.

As a commercial vehicle crosses the scales, its size, weight, and identification are sent to a computer with electronic screening software. The software checks for violations by using the transponder or license plate to look up the carrier’s safety rating, verify the vehicles registration information, and validate the size and weight. Sensors in the roadway track the vehicle’s footprint to allow customized notification on changeable message signs located just before the weigh station exit. The computer then directs the vehicle to continue driving if they passed the electronic screening, or stop at the weigh station for a more thorough inspection if a possible violation was identified. This allows enforcement officers to focus on high-risk carriers.


The Weigh-in-Motion (WIM) consists of a scale and sensors in the roadway. They are used to determine the weight and length of a commercial vehicle as it drives in the WIM lane. The system calculates:

  • Overall length
  • Overall weight
  • Number of axles
  • Weight on each axle
  • Distance between axles
  • Load distribution (left to right)

Automatic vehicle identification

Automatic Vehicle Identification receives a signal from and sends notifications to 915 MHz transponders that are voluntarily placed in commercial vehicles. A transponder reader is located at the site of the WIM and the software uses the transponder number to look up the commercial vehicle registration information. A transponder writer is located near the changeable message signs and sends red or green lights back to the transponder. A red light indicates the commercial vehicle must report to the weigh station and a green light allows them to bypass. Learn about how the electronic screening program works and the use of transponders.

Automated license plate reader

A Transponder Reader mounted next to an
Automated License Plate Reader camera.

An Automated License Plate Reader identifying the
commercial vehicle.

An Automated License Plate Reader identifies the license plate number and the jurisdiction of commercial vehicles. The system consists of two cameras: a standard video camera and an infrared camera. The video camera looks for the license plate and the infrared camera takes a picture. The system then uses optical character reading technology to translate the image into text and assigns a confidence rating. Officers at the scale are able to select the minimum confidence before a license plate read is trusted. The electronic screening software uses the license plate to look up the commercial vehicle registration information. Changeable message signs tell the commercial vehicle if they must report to or bypass the weigh station.

166,800 electric vehicle

registrations in Washington in 2023, up from 114,600 in 2022.

87 wetland compensation sites

actively monitored on 918 acres in 2023.

25,000 safe animal crossings

in the Snoqualmie Pass East Project area since 2014.