XC signs along Fitchburg line

[mannolc12]

I assume this isn't just unique for the Fitchburg line, but what do the XC signs along the route mean?

[MBTA F40PH-2C 1050]

Crossing Circuit activation point for public/pvt grade crossings. You are correct also, in the sense that these signs are very common on all of our territory

[edbear]

XC posts are a B & M standard and mean "Begin Crossing Circuit."