Eugene Raymer, in the bucket, talks to Jeremy Watson of Stansell Electric as they work on traffic lights on Highway 153 near the Target store Wednesday.

Chattanooga traffic engineers are taking some of the guesswork out of left turns. Work began this week on a number of intersections along Highway 153 that will update left-turn signals to include flashing yellow arrows.

The flashing arrow will signal to drivers that they do not have a protected left turn and must yield to oncoming traffic. The idea is to combat some of the confusion motorists experience when they see a green light for through-traffic.

"There are people that get confused and see green [and think] 'that means I can go,'" said Chattanooga traffic engineer John Van Winkle. "A flashing yellow arrow is intuitively more descriptive of what the traffic conditions are. Yes, you can turn, but you have to watch."

The system, called adaptive signal control, will be the first of its kind in Tennessee. Video cameras linked to computers will actively scan traffic. If vehicles begin to back up at a particular light, the computer will signal for it to change to green. Van Winkle said the system makes traffic move more efficiently and safely.

And Highway 153 could use it. The intersections with Hamill and Gadd roads have some of the highest collision rates in the city, according to Van Winkle. On any given day, between 43,000 and 53,000 vehicles use the state route.

Nick Carpenter, an employee at Sports, Wine and Spirits just off 153, said he's almost been hit twice by drivers making left turns.

"This is a pretty bad intersection," he said. "[Highway] 153 could really use all the help it can get. I've had a couple very close calls."

Joanmarie Thackrah, a coordinator for Pulmonaire CPAP Services at the intersection of Gadd Road and 153, said she is very familiar with the crossroads.

"You have to be careful because there are so many people," she said. "I think anything they do to increase driver awareness would be great."

Chattanooga isn't the first city to install the new signals. Lexington, Ky., traffic engineers began installing the flashing yellow arrows in Lexington intersections in 2010.

Steve Cummins, traffic signal manager in Lexington, said they have been very effective.

"We've had a 20 percent reduction in angle collisions," Cummins said. "Those are the T-bone type, right to the door frame."

And, he added, "the community loves" the new signals.

"Once we had about 15 to 20 out and in place, the community started calling, saying ... 'When can we get this on our side of town? Because we like what we saw on that side of town.'"

He said Lexington drivers had no problem adapting to the new system.

"Driver recognition was instantaneous," he said. "We didn't have to teach them or educate them as to what this is."

The signal updates are a phase of Chattanooga's Intelligent Transportation System project.

"It's a citywide system where we can communicate with every signal from our operations center downtown," Van Winkle said.

During this phase, 115 intersections will be converted to the new signals and linked to the downtown operations center.

"We've started on Brainerd Road, North and South Terrace, and now we're going to Highway 153," Van Winkle said. "This phase is a $7.4 million project. It's a lot of equipment and a lot of cost and manpower to make these changes."

But Cummins says it's worth it.

"I'm very happy that Chattanooga's looking to go this direction," he said. "Really, the benefits of it far outweigh just turning a blind eye to it."