B733 works Sunday through Thursday nights from Readville, on duty @ 600pm. Usually it departs Readville at about 715/730pm after MBCR train #821 and heads west to Mansfield. they service the West Mansfield Industrial Park and sometimes stop in Mansfield to pick up cars from the yard on the Framingham Secondary.
Currently there are six customers in the Industrial park, but two of them haven't done rail business in about a year.
B733 also services the Boston Globe in Dorchester & the Americold Storage Warehouse @ South Bay in Boston
Since the "rehab/signal upgrade" of the Dorchester Branch freight speed has been slashed from 30mph to 15mph, and in some spots 10mph because the new cab signal system is junk and the blocks are not spaced correctly. With this new headache and the new Greenbush service B733 usually can't go to the Globe until after the last Old Colony train heads south @ 1040pm.
BTW, this should be in the CSX Forum