Yep, that's how it's done with most traffic lights in central Europe, e.g. http://www.flickr.com/photos/30626457@N00/4580229/
I've never seen lights with that design obscured by snow, and many are LED based now.
I've never seen lights with that design obscured by snow, and many are LED based now.
(The top one a little bit, and the middle one much more so. The bottom one is the clearest because the snow can't build up on the cover of the one below).