If you look at the next photo in the stream - http://www.flickr.com/photos/dustpuppy/4580359 you'll see the red light is still two-thirds visible. Whilst that's not perfect, it's better than nothing. Coverage of the amber (middle) light isn't much of an issue as it's used in transition between the main lights. In those conditions, not seeing the amber isn't going to need much of a behavioural change.