Last week I wrote about some information I found in documentation from a telegraphers' dispute with the railroad. It's a good example of being able to find useful information in unexpected places.
Here's another one.
Don (signaldesign) posted lists of Public Railroad Crossings that the NH compiled on the NHRHTA Forum recently. I hadn't taken a look, since while seemingly interesting enough, I know where the grade crossings in New Britain are. But I knew I would want to grab it just to have the information.
What is helpful is that the date of installation of the automatic gates/signals is noted.