WHY AREN’T AUSTIN’S TRAFFIC SIGNALS TIMED BETTER?
The perception that Austin’s traffic lights are poorly synchronized, or not coordinated at all, is venerable, widespread and deeply felt.
Jared Wall is one of five city of Austin traffic signal engineers who spend their days studying and fine-tuning the city’s 999 signalized intersections, and he knows all too well how the caprices of traffic stymie their efforts. But even he, plying Austin’s overstuffed streets, can fall prey to this notion when a trip from a freshly green light is abruptly halted by red at the next cross street.
“Sometimes I say, ‘Man, I could have timed this one better,’ ” Wall said. But even the best-designed timing plan can be disrupted by accidents, special events, weather or surges of traffic. “Not to discount anything that anyone says, but most people don’t understand the complexities of it.”
Lynne Marcus, 73, a marketing consultant in South Austin, was among the 10 people who reached out to our Austin Answered project with questions (and gripes) about Austin’s traffic signal timing.
Why is it, she wondered, that Austin “signals aren’t timed automatically by actual traffic? This method is so 20th century.”
She is partially right about that. The bones of Austin’s traffic signal control system, and a NASA-esque control room with more than a dozen screens showing various intersections, were funded by $26.5 million from a transportation bond issue approved by voters in 1998. The hardware, software and command center on Toomey Road began operation around 2000, Wall said.
“Before that, it was a tiny little room, one guy with one computer,” he said.
But that bond issue also paid for an overhaul of the traffic signal control software and better vehicle detection equipment. And the spending didn’t stop there. The
city spent another $2 million, starting about 2012, for software changes to help staffers better collect data and quickly adjust several lights in a single corridor, rather than doing it one intersection at a time.
In August, the City Council approved another $2.1 million for updates to the control boxes at the intersections. Wall said 45 have the new equipment, with more on the way.
As for having signal technology that reacts in real time to actual traffic volumes? That picture is complicated.
Getting in sync
About 80 percent of Austin’s intersections have sensors in the pavement or cameras that observe the traffic flow, allowing for timing adjustments at those locations.
Only within the city’s core — from Lady Bird Lake to the University of Texas and from Interstate 35 to Lamar Boulevard — are the traffic lights fully “pre-timed,” Wall said. Even there, observers in that transportation management center, with access to video from 363 intersections in Austin, make timing adjustments in reaction to real-time traffic situations.
But that doesn’t necessarily mean the intersections with sensors or cameras are coordinated with others nearby.
And even when engineers have worked to synchronize several intersections, it doesn’t take much to disrupt the flow. The sensors at one intersection might allow extra time for a pedestrian or a suddenly long line of cars on a side street, and the bestlaid plans are thrown off for a few light cycles — leaving drivers wondering if anyone (or perhaps an incompetent engineer) designed the system.
Wall said the city is experimenting with “adaptive signal timing,” technology that perceives traffic levels at intersections, or a network of intersections, and automatically adjusts red- and green-light time in reaction to the ongoing traffic without human intervention. But Wall said though the specific technology is ever evolving — better sensors, more computing power — such systems have been part of the traffic engineers’ toolbox since the 1970s.
That kind of system, he said, “does have benefits. The tricky part, though, is saying, ‘Are the benefits worth the extra effort and resources it requires?’ They require very advanced (vehicle) detection at every single intersection and a high level of expertise by the engineer monitoring it full time.”
“What we need to determine is, is it better than an engineer going in and re-timing it?” Wall asked. “At this point, we’re still trying to determine if it works for us.”
Kevin Balke, a senior research engineer with the Texas A&M Transportation Institute, said adaptive signals work best in parts of a city where traffic fluctuates from day to day, week to week. Balke said special events centers — the Erwin Center, for instance — are prone to such unpredictable traffic.
Installing adaptive signals citywide, he said, is not generally needed, or what engineers tend to do.
More engineers adjusting the dials
What has been working for the city, at least in areas that aren’t fully saturated with traffic, is better oversight by Wall and his colleagues.
Wall said the goal for years of the city’s Arterial Management Division, which has 38 employees and an annual budget of $9 million, has been to study and annually adjust the timing on a third of Austin’s intersections, or about 300 each year.
But in 2013, with three or fewer signal engineers on staff at any given time, the division tweaked just 169 intersections. Things were even worse the next year, with just 153 signals getting a hard look.
Last year, with five engineers on the case, the division re-timed 350 intersections, according to the Austin Transportation Department.
The underlying goal: improve travel times on the re-timed corridors by 5 percent, on average, even as population and the number of cars increase.
The city bested that last year, hitting 7.7 percent improvement where it made adjustments.
The results have exceeded that goal in some spots, according to the department. Travel times improved 17.7 percent on Slaughter Lane and 21 percent on Enfield Road after signals were re-timed, the department said.
The situation on Enfield, however, has deteriorated during afternoon rush hour because of a ramp change on MoPac Boulevard (Loop 1) — at the behest of the Central Texas Regional Mobility Authority, not the city — that has backed up traffic on Winsted Lane and then to Enfield.
In 2016, the department said, timing changes on Braker Lane signals improved travel times by 20 percent.
Marcus, who spent much of her life in the Boston area and moved to Austin from Albuquerque in 2015, said signals in that New Mexico city seemed better timed and more reactive than the ones here. But Albuquerque road jams pale next to those in Austin, which had the third-worst traffic in the nation in 2014, according to the most recent Urban Mobility Report from Texas A&M.
Albuquerque was 75th, so something other than signal timing could be in play here.
But that’s not much comfort to anyone staring at a long red light.
“Traffic in this city is so horrendous,” said Marcus, who depended on the train system to get around in Boston. “In a city with relatively little public transportation, the least they can do is figure out how to make the traffic move better.”
In August, the City Council approved another $2.1 million for updates to the control boxes at the intersections. Wall said 45 have the new equipment, with more on the way.