Ask MetaFilter questions tagged with trafficlights

Why do traffic lights have a blink cycle?

ChrisManley — Mon, 23 Jun 2008 11:49:43 -0800

Why do traffic lights switch to flashing red after a power outage? I don't get it. We've had lights go completely dead in town the last couple weeks during storms - no blinking. We've also had plenty of flashing reds, which I assume occur after the power has been cut, and then restored.

Why do the lights not simply go red in all 4 directions for 30 seconds and then begin a normal light cycle again?

I googled around, but didn't find much by way of a helpful answer.

How long is that green light?

Cochise — Fri, 16 May 2008 10:11:45 -0800

Help me find NYC traffic light times! I'm trying to find data on New York City traffic lights. Basically, I want to know how long between red lights and green lights in different parts of the city from different years. Or really one single year would be fine. I know these studies are done cause I've read results from them in the past in newspapers, I'm just having trouble finding them. Can anyone help me find this stuff out? Thanks!

Cherries and Blueberries

dead_ — Mon, 27 Feb 2006 08:30:28 -0800

How do emergency vehicles control traffic lights? I've heard that emergency vehicles can control traffic lights, and have plenty of anecdotal evidence confirming this--that they can switch the lights from red to green and so forth.

But how does it actually work?

Do any countries use red and green but not yellow for traffic lights?

gsteff — Sun, 07 Nov 2004 13:06:09 -0800

American traffic lights used to be simply red/green, with no yellow. Are there any countries that still have red/green traffic lights?