Has the red in traffic signals changed?

Matmail:

I've noticed lately that something is different with the red lights used in our street signals. Instead of a nice uniform glow (like the yellow and green), the red seems to emit its light in spots. Why?

-- Seeing Red in Rancho Bernardo

The elves are feeling like roadkill these days. Is San Diego one endless drivathon? Maybe you just have more time to ponder life when you're behind the wheel. Why is the sky blue? Who splattered all that paint on the freeway? If an SUV dematerializes on a deserted off-ramp, does anyone care? If I order a pizza on my cell phone, will they deliver it through the open window of my moving car? Hey, step on it, meathead! Well, I guess that's not a question.

We've received this same question from several of you out there so I guess it's burning a hole in the collective psyche. As the city traffic department tells it, they're in the process of replacing the old lights (light bulb, reflective backing, red lens) with red LED lenses (light-emitting-diode lenses). When the project is done, they say, we'll save maybe half a million on the civic electricity bill. Diodes require much less current than the bulbs. The old-style signals have only a single-point light source; the diode lenses emit light from across the whole surface, making the honeycomb design of the lens easier to see. When and if the technology for green and yellow LED lenses becomes affordable, they'll likely be replaced too. So, one less thing to think about while you sit at an intersection.