Infrastructure

AI-Powered Sensors Improve Traffic in Portland, Maine

A notoriously congested stretch of road in the city of Portland has been eased by sensors that use artificial intelligence to detect traffic volumes and adjust the green light times of traffic signals.

by Randy Billings, Portland Press Herald / November 28, 2018

(TNS) — Dan Pratt knows a thing or two about traffic.

The Metro bus driver’s current assignment includes a busy stretch of Forest Avenue that has some of the most frustrating intersections for Portland-area drivers. Pratt said some days he’s seen traffic backed up for a nearly 2-mile stretch from Forest Avenue Plaza, through Woodfords Corner, all the way to Morrill’s Corner.

“Nobody wanted to be on Forest Avenue between 3:30 p.m. and 6 p.m.,” Pratt said.

But now, drivers like Pratt are beginning to see things change, because of improvements being made by the city.

Crews are wrapping up a 15-month-long construction project at Woodfords Corner, which Pratt says helped ease congestion and made it easier for him to get in and out of the travel lane after picking up riders.

And over the summer, the city activated new traffic sensors at Morrill’s Corner that use artificial intelligence to read traffic volumes and constantly adjusts the green time on traffic signals to move traffic more efficiently.

The city plans to add more of the advanced sensors along Forest Avenue in the coming weeks.

“It has shorted up the wait times a lot,” Pratt said about his experience at Morrill’s Corner. “It seems to know when there’s a lot more traffic on Forest and Stevens Avenue and adjusts those light times.”

Dan Pratt was pleased to learn that the city will install new traffic sensors at other Forest Avenue intersections. Staff photo by Shawn Patrick Ouellette

City officials say they plan to install the advanced sensors at six additional intersections along Forest Avenue in the coming weeks. The intersections include Woodfords Corner, as well as intersections at Dartmouth Street, Ashmont Street, Revere Street, Ocean Avenue and Walton Street.

“All of these sensors will be able to communicate with each other,” said Troy Moon, the city’s sustainability coordinator. “I’m really anxious to see how it will go with the additional intersections. I think it will be really cool.”

TRAFFIC SENSORS, LED BULBS, WI-FI

The new sensors are part of the $8 million “smart cities” program approved by the City Council last year.

The city is wrapping up its initial $4 million investment, which included purchasing streetlights from Central Maine Power and converting them to efficient LED bulbs and rolling out free public Wi-Fi at Monument Square as well as at Post Office and Tommy’s parks. The second phase of financing is pending before the council.

The city is borrowing money for the project over the next 10 years and plans to pay for it with the $1 million in estimated annual savings in energy and maintenance costs.

The traffic sensors at Morrill’s Corner were activated in mid-August. Rather than work on static timers, the new sensors adjust signal length in real time by using pole-mounted sensors to measure traffic volumes 1,000 feet away from the intersection in each direction, Moon said.

According to an analysis by Rapid Flow Technologies, which supplied the technology, the sensors have produced a 20 percent reduction in traffic delays.

The delay is the difference between a free flow of traffic through the intersection and how long it actually took. The sensors were later tweaked, resulting in another 9 percent reduction in delays. The company noted that traffic volumes were relatively flat during the periods tested.

The result may be only a 17-second reduction in the average travel time, but it’s being noticed by people whose commute regularly leads them through the awkward intersection of Forest, Allen and Steven avenues and Bishop Street.

‘I’VE NOTICED A BIG DIFFERENCE’

North Deering resident Julie Rosenbach, who works as the sustainability coordinator in South Portland, has noticed a difference. She passes through the intersection twice a day to drop off her kids at day care.

“I’ve noticed a big difference, especially with cars not backing up on Allen Avenue Extension,” she said. “It used to back up a few blocks.”

Joan Gildart, who lives in Deering Center, also thinks the new system is an improvement. During off-peak hours, Gildart said she can “sail right through” the intersection.

Although she still gets stuck on the Stevens Avenue approach for a couple of light cycles during peak travel times, she said traffic doesn’t back up nearly as far.

Before, “you could be stuck at Walton and Stevens during peak times, but now, not so much,” Gildart said. “It’s definitely a step in the right direction.”

Pratt, the Metro bus driver, was pleased to hear that the new sensors were going to be installed at other intersections along Forest Avenue. He hopes more are in the works.

“Can I make a suggestion?” Pratt asked a reporter. “Valley and Congress and St. John. That light system is one of the top three worst in Portland.”

©2018 the Portland Press Herald (Portland, Maine). Distributed by Tribune Content Agency, LLC.