SmartSensor HD is part of a coordinated effort to address wrong-way driving on a freeway near San Antonio, Texas, and so far, wrong-way incidents have decreased by as much as 30 percent.

Project Team

The San Antonio Wrong-Way Driver Task Force, a coalition consisting of the Texas Department of Transportation (TxDOT), the San Antonio Police Department (SAPD), the City of San Antonio Department of Public Works, the Bexar County Sheriff’s Department, the Federal Highway Administration (FHWA), and the Texas A&M Transportation Institute (TTI); and Twincrest Technologies, an authorized Wavetronix channel partner.

Project Scope

The task force identified a 15-mile (24 km) stretch of US 281 as a high-risk area for wrong-way driving and has implemented a pilot system that includes SmartSensor HD for vehicle detection; flashing wrong-way warning signs on exit ramps; and blank LED message signs that display a message to errant drivers.

Problems and Challenges

In 2011, TransGuide, the ITS system designed by the San Antonio district of TxDOT, recorded 185 wrong-way events and seven fatalities in just four accidents. According to the US National Transportation Safety Board, wrong-way driving accounts for approximately three percent of all accidents on US freeways, but these have a fatality rate up to 27 times higher than other high-speed crashes. Most wrong-way driving occurs when drivers enter freeway exits by mistake, and many of these incidents are alcohol-related. Further, approximately 78 percent of these events occur at night. To prevent accidents, a wrong-way detection system must be able to respond immediately, and the system must be able to catch the errant driver’s attention, especially at night or if the driver is intoxicated.


The San Antonio Wrong-Way Driver Task Force pilot consists of two parts. First, on exit ramps, TxDOT has deployed Doppler devices and flashing “Wrong Way” warning signs; if the Doppler detects a vehicle entering the freeway on an exit ramp, the flashing signs are activated to catch the driver’s attention. Second, on the freeway, SmartSensor HD units are deployed at regular intervals to detect vehicles across multiple lanes; HD’s dual-beam, high-definition radar is able to detect direction of travel as well as accurate volume, occupancy and per vehicle speed. If HD detects a wrong way driver, it activates a message on an LED sign and sends an alert to TransGuide so that authorities can be notified.


After 14 months the wrong-way detection pilot was evaluated. Analysis shows that countermeasures have reduced wrong-way driving events on US 281 by about 30 percent. Cost recovery time for this project is estimated at 1.5 years. Based on the success of this experiment TxDOT plans on installing additional signs and SmartSensor HDs.

For more information on SmartSensor HD, click here.