why do walk signals have that triangular grate?

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Only started noticing this today. In every city I’ve ever lived in (east and west coast US), pedestrian walk signals have this triangular pattern grate over the actual lights that show the walk or wait imagery. Considering the panels use lights that are made to those actual shapes and not a pixelated display, what’s the purpose of the grate?

In: 4

I believe they’re there to stop animals from making their homes inside the lights, which would cause concerns for traffic safety.
It also makes the lights fairly directional, so people can’t see the lights they aren’t supposed to pay attention to, leading to less confusion.

I had to look it up because I couldn’t imagine what you’re seeing. My state doesn’t use these but I would lean towards some sort of protection against vandalism or just protecting them from getting damaged or obstructed.

When I lived in Missouri in the 90s, small birds would hang out in traffic lights at night.

My GF didn’t believe me until one night I showed her the bird’s silhouette.

This was before LED lights, so filament bulbs/incandescent lights were used. These give off heat, while the light is on. As it was a traffic light, it would cycle all night– probably a decently warm place in the winter time.

The grate is there to restrict the angle at which they can be seen. You will sometimes see similar grates on traffic lights when they are close enough such that there might be confusion about which lights are supposed to signal drivers in specific places.

Walk signals are not often placed in such a way that pedestrians would be confused about which signal is for them, but they serve another purpose in that they keep drivers from seeing the signals. Walk signals often will have a countdown before they change to a “do not walk” signal, and some drivers waiting at the light may use this to predict when the traffic lights will change. Drivers thinking they know when the light will turn green may “jump the gun” and begin to go before it actually flips, and this can bring them into conflict with those drivers who blow through lights moments after they turn red. Both sets of drivers bleeding into the same buffer period can result in accidents.