Automatic Vehicle Identification (AVI)

Vehicles traveling on toll roads as well as free roads can be identified by their radio frequency identification (RFID) transponders commonly called a toll tags. These devices provide a unique radio identification code when read by AVI system equipment. Small yagi radio antennas pointed at each lane can identify specific vehicles as they pass. These antennas are most often attached to overhead sign structures, overpasses, and toll gate structures. Portable trailer AVI readers are also commonly used in construction areas and to conduct temporary traffic surveys. Even handheld readers can be used to query the transponder tags.

AVI systems were originally developed to collect tolls. Today they are also used to track the movement of tagged vehicles. By tracking the movement of specific vehicles detailed traffic studies can easily be compiled. Real time traffic monitoring can also be accomplished using the AVI system. Rather than measuring the traffic speed at one or more specific locations an AVI monitoring system can observe the actual travel time between points by tracking specific vehicles. By example the Houston TranStar system uses Harris County Toll Road Authority (HCTRA) "EZ-Tags" to collect movement data from transponder readers every few miles along Houston freeways.

In 2005 the Texas Legislature considered House Bill 2893 that if it had passed with its original enrolled wording would have required a RFID tag to be placed inside every Texas Motor Vehicle Inspection sticker. House Bill 2893 called them "Special Inspection Certificates." Those tags would have been compatible with RFID tag interoperability standards recently adopted for use by all Texas toll roads and would have been readable by AVI systems statewide. The proposed Bill intended to provide RFID tags that the state or a private contractor could use identify uninsured vehicles and levy civil penalties on behalf of the state. Once placed on vehicles the use of those tags could and would naturally have expanded to include toll collection and vehicle identification for other purposes including tracking vehicle movements. House Bill 2893 failed to pass.