What is up with Austin’s traffic signals?

This story is part of KUT’s ATXplained series, which solicits story topics from listeners and investigates those that get the most online votes from the public. The winning topic for this segment was: traffic light synchronization.

Picture it: You’re idling at a red light. Maybe it seems like other drivers are getting all the green, and why can’t you have some? Then, later, maybe you’re not at a red light. Maybe you’re cruising what seems to be a sea of green.

This is traffic light synchronization, when a string of lights is timed so that you can simply fly along your route. You could get spiritual about it. You could say it feels like someone has wrenched open the gate to commuter heaven.

City of Austin signal engineer Jonathan Lammert may not be some sort of god, but he does feel powerful at times. “Powerful – but responsible,” he says.

Standing on the corner of Seventh Street and Shady Lane, he is staring at the innards of a traffic signal control box. Lammert has just made the light at Shady turn green 25 seconds earlier than it did before. Every day he drives roads where the traffic lights are synchronized. And, if he feels it necessary, he’ll tweak the timing of these lights so that drivers hit that sea of green as often as possible.

On a Thursday afternoon, he drives the stretch of Seventh Street between I-35 and Shady Lane. Lammert speaks aloud the mathematics going on in his head.

“Since Springdale (Road) was green well before we got there, if we want to make Shady go green earlier, by like 20 to 25 seconds, then we could get through Springdale just as it turns green, and then we could get through Pleasant Valley (Road) when it’s still green,” says Lammert. “So that’s one thing that we’ll keep in mind.”

What Lammert is getting at is that an individual traffic signal is not an island. If you change the timing of one, it affects the others. So when he finishes up at Shady, he calls someone who can tweak the timing of the lights remotely and asks that Springdale get the same adjustment.

“Maybe I’m missing something, but I think there’s opportunity for improvement in Austin traffic lights,” says Austinite David Kobierowski, who submitted the winning question for this segment of the ATXplained series: “When will Austin’s traffic lights be synchronized?”

“You have to time the shifting of your car, your lane change, everything, so fast, and you have to be the first one out of the gate,” says Kobierowski, who drives a car with a manual transmission. “That’s the way you get to the next light before turning red. When the first light turns green, then the second one should turn green, maybe a couple seconds later.”

Kobierowski is driving to the Airport Boulevard exit off I-35 South. There, a set of lights frustrates him, starting with the left turn onto Airport. “But this is green, and this one’s red,” he says.

The cars waiting at the red light are almost backed up to the green light. “I don’t see why these lights can’t be synchronized so that as soon as that light turns green, instead of this one turning red, it turns green,” he says.

“Right now we have about 85 percent of our signals synchronized, and we have about 1,000 signals in the city,” says Jim Dale, assistant director of traffic management for the Austin Transportation Department. “We may not need to hit 100 percent, because some of those signals are so far removed from other intersections that if we just let them what we call ‘run’ – instead of (being) synchronized, ‘run free’ – it can provide a better level of service, or better … minimize delay for travelers, if we just run it isolated.”

Dale explains that if one light is 2 miles from the next, it’s hard to predict what will happen in those 2 miles – so it doesn’t make sense to preset the lights. Plus, the roughly 850 lights that are already synchronized keep the department busy enough. It’s the work Lammert does – going around, driving the roads, retiming the lights.

“We’re striving to retime one-third of the signals every year; that’s the national best practice,” says Dale. “This year we’ll time 200; it’s about 20 percent.”

Dale says the department is hiring another signal engineer so it can hit its one-third goal next year. The city is also investigating new technology – called adaptive signal control – that would do the work of a signal engineer, feeling out the patterns of drivers and automatically retiming lights. But, says Dale, although the technology does the work of a human, it doesn’t remove the need for one.

“Some of our traffic – there’s a little bit of chaos to it, as well,” says Dale. “All of us … have different behaviors in how we decide to drive. There’s just so many things happening.”

“There is an art to it,” says Kevin Balke, a researcher with the Texas A&M Transportation Institute. “There are people that can do it much better than others.”

Balke says signal engineers could be thought of as artists rather than scientists or mathematicians: “They have that feel for the way traffic flows up and down the roadway. It is very tempting to look at the numbers and plug the numbers in. But the numbers only get you that starting point. The way you really get a system working at its optimum is to drive up and down the roadway.”

Back in the car with Lammert, he has just changed the signal at Shady. And, remember how he immediately called in that change at the next light at Springdale? Lammert was talking to Kenny Moses, a traffic system technician in the city’s Traffic Management Center. To say that Moses is surrounded by screens would be an understatement. Moses has three at his desk, plus about 14 on the wall in front of him. These screens show intersections throughout Austin – Cesar Chavez and South First streets, Guadalupe and Dean Keeton streets. In other words, Moses’ job is to stare at and respond to Austin traffic.

Laughing, Moses says, “No, no, no,” when asked if he feels a sense of power staring down at all of Austin’s traffic from his desk chair.

What Moses loves about his job is what most people hate about the nature of traveling by car: “It’s something different every day,” he says. “It doesn’t get boring. There’s always something else – something else going on.”

Everyone interviewed for this story spoke about the limitations of light synchronization. It has the power to move traffic along, but it can’t increase capacity on the road. “Even though you get more green time there,” said Moses, “if we don’t make changes down the road, you’re gonna catch the red there, and what you’re doing is just moving the traffic jam from point A to point B.”

Then, there’s the future of traffic lights. There are now cars on the market that communicate with one another. The traffic engineers interviewed for this story said they saw a future without traffic lights – one in which cars tell one another to stop or to go.

As for Moses, he’s not worried about his job. Traffic, he says, will always require a human at its helm.

Photo by Garrett made available through a Creative Commons license.