If you've ever thought that yellow lights at intersections are too short, you're not alone. In fact, the length of the yellow light may even be changing thanks to the frustrations of one Oregon man.
When the wife of Mats Järlström received a ticket for running a red light, which had been yellow when she began crossing through the intersection, Järlström decided that things needed to change. Not satisfied by simply having the ticket dismissed, he began building a case for why the length of yellow lights should be lengthened, one that he would pursue for years.
Järlström was ultimately successful, and his success has already had reverberations, including the release of a study that has confirmed that yellow lights may, in fact, be too short in certain circumstances.
As Car and Driver explains, the amount of time allotted to yellow lights was set in the 60s, arrived at using the kinematic equation. And while it's comforting to know that the time length has scientific basis, there are certain considerations that were not factored into the original equation:
"... the kinetic equation works fine to eliminate what's known as the dilemma zone... as long as the vehicle speed stays constant.... But what if you slow down, as it to turn? Then the equation falls apart and you might be hanging out in the middle of the intersection when the light turns red."
The study that was triggered by Järlström's case was conducted by the Institute for Traffic Engineers, and they're conclusion backed Järlström's own findings: yellow lights are indeed, sometimes, too short:
"Ultimately, the report acknowledges that there are so many variables at play - intersection width, driver age, vehicle length and condition, weather, reaction times, grade - that there's no perfect solution."
This confirmation will hopefully lead to traffic controllers and governments around the world taking a closer look at how yellow lights are functioning in their cities, but, even if this doesn't happen, many people will now be able to rest easy knowing that they were right to think yellow lights were too short, and there's room to fight it.
For more on this story, check out the original article by Ezra Dyer in Car and Driver.