The PTC test trains are 4-car flat sets with MBBs that were made good enough to run as trailing cars but not carry passengers. That's probably what you saw.
Moderators: CRail, sery2831
sonicdoommario wrote: ↑Sun Jun 30, 2019 9:47 am The 1645 is actually a lead car on the South Side. Also, the 1636 is somewhere down south too.The set with 1645 as an active control car, and 1636 directly behind it, was on Track 10 at South Station this morning. Now that the 1600s have ACSES as part of the PTC program, segregating them north is no longer an issue.