I just heard D3 tell FI-3 at Ayer about 18:30 hrs they would be relieved by "MA -15 out of Mechanicville". I wish I could have recorded the incredulous response from train crew. Several minutes later dispatch informed crew "taxi was delayed and would be an hour late"
MA-15 (Mechanicville-Ayer) is likely a return of an Ayer-based crew out of the hotel in New York. Maybe there was nothing on the west end for them to re-crew if one of the intermodal trains was delayed, or they were the best available and qualified crew for whatever FI-3 was up to.
I can recall a similar situation where we cabbed an Ayer crew from the hotel in New York to Worcester to take a SEPO up from Burncoat Street. The cab made great time and they took the train up the branch and over to Lowell, cabbed back to Ayer all in 12.