I've seen them there before. In fact, I saw a huge one in 2010 that I was able to take a short video. Quality is not the best and far, but look closely at the middle of the screen or pause it at 4 seconds.
http://www.youtube.com/watch?v=y31DG5L_6U4

I was told by the check station operator at RR Road that the FWC moves them from other places to the GS sometimes