OK, this question could just be theorized, but past experience would definately help. The line I found the following on is/was the New York Central. I started the day trying to dig pole stumps, I ended up walking the line and just raking an area about 12'X12' around each stump, about 6"-1' down. I found a lot of frags, but some of them could definately be strong signs that there could still be good glass lurking underground. I'll start with the weakest. This Brookfield(CD?) had some nice bubbles, and a large fold in the glass over the embossing, not that great, but this is the first Brookie I've found on this line after walking 24 miles of it. Were they common in these parts?