CSX's B&A mainline runs over the Berkshires through Pittsfield over the mountain through Chester down to Westfield, West Springfield. There's about 12 freights a day and 2 Amtraks. Unfortunately most run late afternoon thru early morning. You may get lucky with one mid day train but it's hit or miss. There are now 3 webcams along the route with streaming video that you may want to check out to see the pattern through the area.
First one is at the Chester Railway Museum in Chester Mass.:
The second one is from the Pilgrim Candle Building looking out at the tracks over the bridge in Westfield Ma.:
The third one is in W. Springfield at the Front St. crossing:
https://www.mass.gov/info-details/morga ... ic-cameras
As Jeff said the Housatonic RR. runs through GT. Barrington, Housatonic, Stockbridge, Lenox and Pittsfield. If you have a scanner you may be able to catch their Canaan-Pittsfield turn.