The Arizona Department of Transportation is continuing to upgrade freeway ramp meters that are used to improve the flow of traffic, especially during busy rush hours, ADOT officials said.

Ramp meter upgrades were completed this year along the 60 miles of Loop 101 in the Phoenix area – from near I-10 in the West Valley to Loop 202 in Chandler, according to ADOT.

The improvements have not required the installation of new ramp meters. Rather, officials said ADOT has used enhanced computer programming to operate the timing of the meters’ alternating green and red traffic lights.

“The improvements mean each ramp meter can now respond to traffic conditions farther away from any one specific freeway location,” ADOT officials stated in a release.

For example, an adaptive ramp meter is able to respond to slowing or improved traffic conditions beyond its immediate on-ramp location.

Data about conditions a mile ahead along the freeway allows the meter to adjust the timing of its green and red lights. The process can be repeated along several miles of a freeway until traffic conditions improve, according to ADOT.

Adaptive ramp meters also have been set at times to operate outside of traditional weekday rush hours to help manage traffic flow when nearby sporting events, concerts and weekend construction closures are taking place.  

ADOT officials said the state will continue to expand the use of adaptive ramp metering to additional sections of freeway in stages over time.