Why do traffic lights switch to flashing red after a power outage? [more inside]
posted by ChrisManley on Jun 23, 2008 - 15 answers

Help me find NYC traffic light times! [more inside]
posted by Cochise on May 16, 2008 - 8 answers

How do emergency vehicles control traffic lights? [more inside]
posted by dead_ on Feb 27, 2006 - 15 answers

American traffic lights used to be simply red/green, with no yellow. Are there any countries that still have red/green traffic lights?
posted by gsteff on Nov 7, 2004 - 10 answers