I-17 wrong-way vehicle alert system holds promise

PHOENIX – A loud horn sounds in the Arizona Department of Transportation’s Traffic Operations Center. That alarm signals a possible detection of a wrong-way vehicle by one of the thermal cameras watching the off-ramps and travel lanes along 15 miles of Interstate 17 in Phoenix, part of a detection-and-warning system that’s the first of its kind in the nation.

While the same alert goes immediately to the Arizona Department of Public Safety to help troopers reach the scene as quickly as possible, a window appears on operators’ work stations showing video from the thermal camera and providing other data. Using a computerized decision support system, operators can immediately activate digital message boards in the area alerting drivers to the potential danger and instructing them to exit the freeway.

If the detection is at an off-ramp, an internally illuminated wrong-way sign with red flashing LEDs has activated, positioned to attract the attention of wrong-way drivers, most of whom are impaired, often severely.

As ADOT looks toward expanding use of the technology, the agency is studying results from the I-17 system that went into operation in January at off-ramps and at intervals along travel lanes between Interstate 10 and the Loop 101.

To date, the system has detected more than 15 vehicles entering I-17 off-ramps and frontage roads in the wrong direction. None of these vehicles has entered the I-17 mainline lanes, with the majority of drivers turning around on exit ramps.

“While the system can’t prevent people from driving while impaired, the results so far are promising as a countermeasure to this deadly behavior,” said Brent Cain, who leads ADOT’s Transportation Systems Management and Operations division. “The goal is reducing the risk of wrong-way crashes by saving valuable time when a wrong-way vehicle is detected.”

The $4 million system includes 90 thermal detection cameras positioned above exit ramps and the mainline of the freeway between the I-10 “Stack” interchange near downtown to the Loop 101 interchange in north Phoenix.

ADOT and partner agencies will evaluate the system’s performance over approximately the next year while it looks toward using it on other freeways, including the new Loop 202 South Mountain Freeway that’s scheduled to open in late 2019.

ADOT will continue working with the Department of Public Safety and the Governor’s Office of Highway Safety to promote efforts to stop impaired driving.

Technology like the I-17 thermal camera system cannot prevent all wrong-way crashes from happening. The primary goal is reducing the risk of serious crashes by alerting DPS and ADOT to wrong-way vehicles much faster than waiting for 911 calls from other motorists. Faster detection is a key to giving law enforcement officers an improved chance of responding to a wrong-way vehicle.