SmartSensor Advance and SmartSensor Matrix are integral parts of an Oregon system that notifies drivers of slow or stopped tunnel traffic in order to prevent rear-end collisions.

Project Team

The Oregon Department of Transportation; and Advanced Traffic Products, an authorized Wavetronix channel partner.

Project Scope

The Oregon Department of Transportation has implemented an advance warning system that alerts drivers entering a tunnel to the presence of slow or stopped traffic at the tunnel’s exit. The system uses a combination of SmartSensor Advance and Matrix units to detect traffic; if certain conditions exist, the system activates a flashing sign that warns drivers to slow down.

Problems and Challenges

Transportation officials in Oregon were faced with a dangerous traffic situation at the interchange between Interstate 84 and Interstate 205 east of Portland: a significant number of rear-end collisions were occurring because drivers were unaware that traffic ahead of them had slowed or stopped. The problem occurred at a tunnel that drivers must enter to merge from westbound I-84 onto southbound I-205. There is a sharp left turn just after the tunnel and traffic often backs up to the tunnel exit, particularly during peak congestion times. Drivers entering the tunnel at full speed were unaware of conditions ahead of them, and could not see stopped traffic around the turn.


ODOT Signal Manager Doug Anderson worked with ATP to install two SmartSensor Advance units and one SmartSensor Matrix near the left turn: one Advance detects traffic backups on the merge ramp; the other Advance faces the tunnel exit to detect traffic speeds at the beginning of the turn; and the Matrix sensor faces east to detect traffic that has stopped in the turn. If any or all of the sensors detect slow or stopped traffic, the detection will trigger a flashing message sign at the tunnel’s entrance that warns drivers to reduce their speed.


ODOT’s innovative use of Advance and Matrix, in conjunction with the flashing warning sign, has made a difference for vehicles leaving I-84 to join I-205 at this interchange. “Engineers have noticed a change, but the quantitative decrease in the number of accidents is still being determined,” Anderson says.

For more information on SmartSensor Advance, click here.