Already Burning Out?

Defective LEDs in San Francisco traffic signal

San Francisco replaced most of its traffic-signal bulbs with LEDs in 2002 and 2003. Already, some of them appear to be failing, as with the dark LEDs on this green signal at Spear and Harrison Streets. No, the face of the signal isn't marked up. The dark spots are LEDs that are no longer working. This photo was taken in July 2006.