In 2017 Motherboard shared the story of Mats Järlström, the Oregon electrical engineer who challenged the state’s traffic light timing. What began as a simple quest to help his wife avoid an unfair ticket turned into a multi-year saga after the Oregon Board of Engineers fined him thousands of dollars—simply because he dared discuss the issue when he wasn’t technically a traffic engineer.
Unlike many stories, Järlström’s saga finally has a happy ending. Last week, the Institute of Traffic Engineers released the findings of a multi-year study. It announced it was adopting Järlström's formula to determine traffic light timing, which should ultimately lead to traffic penalties being more fair, while also improving public safety. “It feels very good” to be vindicated, Järlström told Motherboard. “I also feel relieved to have reached this goal after investing so much time trying to convince so many entities that something was wrong and needed to be corrected.” His saga began back in 2013 after his wife received an automated traffic ticket. After taking a look at the evidence, Järlström concluded she had been unfairly ticketed for running a yellow light. After looking deeper he noticed something else: the mathematical formula long used to determine light violations didn’t account for real world human behavior. When he took his findings to the Oregon Board of engineers, he was fined $500 for practicing engineering without a license.
"I'm not practicing engineering, I'm just using basic mathematics and physics, Newtonian laws of motion, to make calculations and talk about what I found," Järlström said at the time. Järlström sued the board in 2017. Earlier this year, he won his lawsuit against the state of Oregon, Judges ruling that Oregon’s so-called “Title Laws,” which state that citizens can’t profess to be engineers unless they’re registered with the state, violated his Constitutional right to free speech. Now, his findings are likely to be adopted not just in Oregon, but everywhere.
The yellow traffic signal was first introduced in 1920, and the current scientific solution standard was adopted in 1965 and hasn’t been changed since. Järlström told Motherboard the first major problem with the traditional yellow light timing formula is it only accounts for standard sized vehicles driving straight through an intersection at a constant speed.
Järlström said the existing model doesn’t account for the deceleration required before safe and comfortable turning maneuvers (like turning right), unfairly penalizing drivers. It’s the reason why many drivers accelerate into and through the intersection to ‘beat the light,’ putting others potentially at risk, leading to unfair automated traffic tickets. “A second issue is that the input variables, such as the perception-reaction time and the maximum safe and comfortable deceleration values used to calculate the yellow change interval, do not include all driver-vehicle combinations legally on the roadway, which puts some drive-vehicles in a dilemma such as trucks with air brakes—or older drivers,” he said. To fix the problem, Järlström developed a new equation that incorporates potential speed variations as users in varying vehicle types (and with varying intentions, like right turns) approach the yellow light. “By doing this, it will create an area in the roadway where drivers can both stop or go to solve the ‘driver indecision zone’ to avoid having drivers accelerating unsafely through our signalized intersection,” he told Motherboard.
The ITE’s new guidelines recommend that cities adopt Järlström’s new methodology. As voluntary guidelines they don’t have to do so, but many likely will.
“I wish that the federal government will issue a uniform standard across the United States, and I am working towards an international standard, which makes it easier for us drivers to know how to behave when we encounter a yellow traffic signal anywhere in the world,” he said.
So why was it so hard to challenge the established thinking on something that’s such a common everyday experience for people around the planet?
Järlström told Motherboard that because traffic signals have been around for roughly a century, an established dogma had calcified up around those systems over time. People simply never thought to challenge not-so conventional wisdom, he said.
“It was the red light camera industry that brought the problems to the surface, so individuals like myself, Jay Beeber, and others and organizations such as the National Motorist Association felt a need to correct the issues, Järlström said. “It has been a long journey to reach this goal.”