Weigh station e-screening technology

Goals

We are the lead Innovative Technology Deployment (ITD) agency for the state. The ITD program is part of the Federal Motor Carrier Safety Administration. It was created to use technology to improve commercial vehicle safety.

• Identify higher-risk carriers to remove unsafe commercial vehicles from the road.
• Focus resources on vehicles more likely to be non-compliant.
• Allow good vehicles to bypass weigh stations to reduce congestion.
• Save time & fuel for good carriers to lower their shipping costs.
• Encourage carriers to follow rules so they qualify for a bypass.

Electronic screening process

The e-screening system directs vehicles into the weigh station for further inspection. E-screening results are not used to issue citations. The system functions solely as a tool to help officers decide which vehicles to inspect.

E-screening system

This technology is located at 11 weigh stations and four virtual weigh-in-motion sites. Roadside equipment is placed about half a mile before the weigh station. Based on rules set by officers, trucks are told to stop or go past the weigh station. This technology helps officers focus on high-risk carriers or trucks needing a permit. Common violations are:

• Unsafe carriers
• Registration issues
• Overweight
• Speeding
• Tailgating

 Unsafe carriers

Unsafe carriers have a high inspection selection system (ISS) score. The United States Department of Transportation rates carriers on:

• Unsafe driving
• Crash indicator
• Hours-of-service compliance
• Vehicle maintenance
• Controlled substances and alcohol
• Hazardous materials
• Driver fitness

How it works

• Weigh-in-motion equipment collects the vehicle’s size and weight
• Identification equipment is used to look up the registration and safety rating
• Electronic screening software check for violations
• The truck is told if they can go past or if they must stop at the weigh station

Roadside equipment

Weigh-In-Motion (WIM)

The 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 (AVI)

Identifies a transponder inside the vehicle.

• Carriers register a 915 MHz transponder to a VIN.
• A transponder reader located at the WIM receives the signal.
• The e-screening system looks for registration or carrier violations.
• A transponder writer located at the message signs sends signal to transponder.
• Red light: vehicle must stop at the weigh station.
• Green light: vehicle can bypass the weigh station.

License plate reader (LPR)

The LPR is located at the WIM and identifies the plate number and jurisdiction 

• A standard video camera locates plate.
• An infrared camera captures image.
• Optical character recognition translates image to text and assigns confidence rating.
• Officers set minimum confidence level.
• The e-screening system looks for registration or carrier violations.
• Message signs: “TRUCK BYPASS” or “TRUCK MUST EXIT TO” 

Tire anomaly system

Sensors located at the WIM to detect missing, underinflated or mismatched tires. The system uses multiple sensors for comparison to ensure accuracy. 

• Pressure sensitivity in road sensors measure tire contact.
• The system compares the footprint of 2 tires right next to each other.
• The system does not check two tire axles.
• A violation occurs when the footprints do not match.
• The system provides the officers with a diagram indicating which tire set to inspect. 

Information collected

The e-screening system does not contain any personally identifiable information. The e-screening system does not screen vehicles classified as passenger cars. The e-screening system results are exempt from disclosure under RCW 42.56.330 (6).

Information used to electronically screen commercial vehicles

• Overview image of the vehicle – primarily the tractor (the pulling truck)
• License plate & registration information
• USDOT number & carrier information
• Overall vehicle length (truck and trailer)
• Overall vehicle weight (truck and trailer)
• Number of axles (truck and trailer)
• Axle spacing
• Weight per axle
• Left/right load distribution
• Speed
• Distance from preceding vehicle
• Transponder (at locations with a physical weigh station)
• Height (at locations with a physical weigh station)