There seems to be channels in use for other things than what is posted in most "frequency lists" the only real way to find out what to put in is to search the entire VHF railband and you can then decide what frequencies make the cut. Around here, I have most all of them in my scanners, as Toledo is a major rail traffic area. About half of them have traffic on them most of the time, the others come to life when there is a wreck or track crew is working. Sounds like your area is busy to the point 16 freq won't be enough to get everything, not even close.