ADOT tests ramp meters on SR51 to improve traffic flow

PHOENIX (KSAZ) - Drivers along State Route 51 in central Phoenix are experiencing some longer wait times at some entrance ramps.

The Arizona Department of Transportation hopes this project will reveal how the signal adjustments can impact freeway traffic. So drivers could be sitting at a red light a little longer while they try to figure this out.

For three weeks, drivers entering the northbound lanes of the 51 can expect to wait a few seconds longer at the ramp meters.

"The goal is to see if technology can help us make more efficient use of those lanes on state route 51," said ADOT's Steve Elliot.

Currently, meters are programmed with predetermined red light intervals. This new technology will respond to the actual volume of traffic entering the freeway.

"What will happen is the ramp meter lights will adjust to the traffic on the highway and that's determined by what we call loop detectors that are in the highway that find out how many vehicles, the overall load on the freeway and the speed of the freeway. That information gets to the metering system and if the freeway is approaching capacity, then the system might hold traffic a little bit longer," explained Elliot.

On a two lane entrance, drivers typically wait 2.5 seconds for the red light. During the testing, you can expect to wait about 7.5 seconds. On a one lane entrance, drivers wait 3 seconds. During testing, that will now be around 9 seconds.

"We hope that using this technology, it will allow us to keep the freeway more efficiently and save everyone time," said Elliot.

Some drivers we spoke with don't mind the added delays, especially if it can potentially help future commutes.

"It's good for traffic. Makes it flow off and on easier," said Steve Baker.

Online: azdot.gov/RampMeters