SH-99 Grand Parkway from US-290 to I-45 is now open. No tolls on this segment of SH-99 until February 15.
The Greater Houston Transportation and Emergency Management Center City of Houston Harris County METRO Texas Department of Transportation
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Houston TranStar AVI Traffic Monitoring System

Introduction |  AVI Technology |  How It Works

AVI Technology

The system uses Automatic Vehicle Identification (AVI) technology developed by the Amtech Systems Division of TransCore to collect the real-time traffic information. Houston was the first city to apply AVI technology for monitoring traffic conditions.

AVI Station The AVI system operates through the use of AVI antennas and readers which are installed on structures along Houston area freeways. The AVI antennas and readers monitor the passage of vehicles equipped with transponder tags. The transponder tags are powered by a small battery which enables them to reflect signals transmitted from the antennas/readers.

Transponder Tag