Red Yellow Green
In Traffic I make a passing mention of the evolution of traffic light sequences:
Others wanted the yellow light shown before the signal was changing to red and before it was changing from red back to green (which one sees today in Denmark, among other places, but nowhere in North America).
Reader Claire writes in to note that she remembers this sequence being used in the U.S.:
I distinctly remember passing through signals of this type on arterial streets in Chicago between 1977 - 1983. They were mostly located west of the L tracks on arterial streets like Belmont, Armitage, Fullerton, Devon, and Ashland.
Now, I didn’t say they were never used in the U.S., just that they aren’t anymore — although I may be wrong here and I’d be curious to see an example. She helpfully points us to Willis Lamm’s Traffic Signal page, which contains video examples of these “really funky signal phases.”
I’ve seen international studies on the potential problems with the red-amber-green phase, but haven’t really heard or read an account of why these phases vanished in the U.S. (though I’m sure the information is out there, in some back issue of the ITE Journal). I can imagine there are pedestrian issues, not to mention intersection clearance issues. And given that hardly anyone drives a manual shift in the U.S., one of the perceived virtues of that system is now largely lost here, like an old piece of slang no one uses anymore.
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This entry was posted on Tuesday, July 14th, 2009 at 12:01 pm and is filed under Traffic Engineering, Traffic Gadgets, Traffic Signals, Traffic Wonkery. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
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July 14th, 2009 at 12:42 pm
I think they have them in Vancouver BC.
July 14th, 2009 at 3:12 pm
In Russia, it seemed to me that the Red+Yellow preceding the Green was a signal to the drivers to put it in gear and gun their engines, the sound of which alerted pedestrians to get the hell out of the way. I remember being terrified at the site of a babooshka hobbling as fast as she could with her stuffed grocery bags to get out of the way before the cars came storming through. I’m not so sure they would have waited.
I’ve never seen anything but green-yellow-red-green in Vancouver, but I haven’t been there in 10 years.
July 14th, 2009 at 6:28 pm
I remember a red+yellow crossing of the Midway Plaisance in Chicago in the 1990s, perhaps on Woodlawn? It was gone when I checked earlier this year, though.
July 15th, 2009 at 9:13 am
I’ve seen the amber prior to red is used in Montréal, among some other places at least in Québec.
July 15th, 2009 at 9:17 am
er… that is, amber prior to green. Sleep deprivation is a bit of a theme this week.
July 19th, 2009 at 2:19 pm
When I was a kid visiting suburban Baltimore in 1947, the amber light was lit before green. I wish they did that now, especially because I am one of those eccentric nuts who has a manual transmission in my car. Knowing when the green will come on would give me time to shift from neutral to low. How, I have to watch the light for the cross traffic.
On a slightly different note, probably a manual transmission is safer than an automatic transmission. Sometimes an accident occurs when a driver hits the accelerator instead of the brake. Under those low speed conditions, with a manual transmission, probably the driver would have his left foot on the clutch so, if he hit the accelerator instead of the brake with his right foot, little would happen. Unfortunately, I have been unable to find research on this.
July 28th, 2009 at 8:28 am
I remember seeing yellow before green in Montréal or Québec, maybe 15+ years ago. I was told that it was a cue for everyone to get in-gear so everyone was ready to go at the same time. Also, it was a cue for anyone crossing the street to start running for the sidewalk. After seeing that I couldn’t understand why we didn’t have that here.