Per Wikipedia: on the NEC, which the Worcester Line parallels at Back Bay and ultimately joins at Cove Interlocking:Random question (re: pic #10): why does Lansdowne, a two-track station, have them labelled Track 5 and Track 7?
Here, track 1 is the western "southbound main" track, so looking at somewhere like Attleboro which has turnouts to create a 4 track section, it would be tracks 3-1-2-4, and Providence is also 7-5-3-1-2 (7 is the freight passer so it doesn't have a platform, but this is why PVD doesn't officially have a track 4) Once the Worcester Line / CSX Boston sub gets out of "NEC main line" territory it reverts to tracks 1 and 2.Tracks 1 and 2 are considered the primary mainline tracks; the track numbering scheme used in the Boston area uses only odd numbers for additional tracks on the Track 1 side (hence Tracks 3, 5, and 7 [at Back Bay] and even numbers for tracks on the Track 2 side. The Orange Line tracks and platform lie between these two groups of mainline rail tracks.