The Arizona Department of Transportation is testing wrong-way vehicle detection devices next to three more off-ramps along Phoenix-area freeways as part of an ongoing research effort to reduce the risk of wrong-way crashes.
The detectors, manufactured by TAPCO, Inc., were installed last week along the northbound Interstate 17 exit to State Route 74 (Carefree Highway), the eastbound Interstate 10 exit at Ray Road and the northbound Loop 101 (Agua Fria Freeway) off-ramp at Thunderbird Road.
The agency has been testing two other detection devices, manufactured by another company (Wavetronix), which were installed late last year along a pair of Loop 101 exit ramps in the West Valley.
The TAPCO system includes radar and camera sensors designed to detect wrong-way vehicles on freeway exit ramps. When a vehicle is detected, the system activates blinking red LED lights on two “wrong way” signs to try to warn the driver they’re traveling the wrong way. During the testing stage, the system also is set up to send email messages with photos to notify ADOT staff and the Department of Public Safety that a wrong-way vehicle is detected.
The three locations where the system is being tested were selected based on previous research, including figures from the Department of Public Safety on 9-1-1 emergency calls reporting wrong-way vehicles.
A team of ADOT engineering consultants is conducting a study of wrong-way vehicle detection and warning systems, including a review of potential countermeasures. The study is scheduled for completion in September.
In June 2014, as part of a pilot project, ADOT crews installed larger and lowered “wrong way” and “do not enter” signs at six freeway interchanges in the Phoenix area. Large white pavement arrows pointing in the correct direction of travel also were added on the exit ramps at those interchanges. The pavement arrows are outlined with raised pavement markers that include red reflectors pointed toward a wrong-way vehicle.
More than 500 of the larger and lowered “wrong way” and “do not enter” signs have since been installed along dozens of state highway off-ramps. In one project earlier this year, ADOT used approximately $300,000 in available highway maintenance funding to manufacture and install larger signs, as well as pavement arrows, along approximately 90 off-ramps around the state. The work was completed in June (2015).
The agency has adopted the larger and lowered wrong-way signs as a design standard, meaning the larger signs also will be installed on additional off-ramps when highway projects include sign replacements.