on Mon Feb 11 16:32:13 2019, in response to Re: Park Avenue (Brooklyn), posted by Express Rider on Mon Feb 11 13:57:36 2019.
Until Chrystie, the rule was than any train passing through Bkln enroute to Manhattan regardless of its point of origin was northbound. The track numbers even bear this out since under the BMT/IND tk numbering system, even number tks are northbound and odd numbered tks are southbound. At the physical south but RR north end of Chambers St the track numbers change since the Nassau St portion of the line is considered to be Southern Div rather than Eastern so J2 tk becomes R1 Tk. The towerman at Broad St listed all trains on the train interval sheets passing the interlocking as northbound from Chambers and southbound to Chamber and that included the Culver and West End trains which were actually southbound going towards the Montague St tube. This really presented little difficulty until the Jamaica Line was through routed with the Brighton Lcls into the Southern Div as the QJ. To eliminate confusion, the TA specified that QJs operating towards Stillwell would be designated southbound and Qjs going towards Jamaica would be designated northbound. KKs and Ms along Bway Bkln going in the same physical direction, however remained northbound towards Manhattan and southbound lvg Manhattan so the confusion was just moved from one location to another. In 1972, when the M was extended to the Brighton Line and the former QJ renamed the J truncated at Broad St, the M was redesignated S/B to Stillwell and N/B to Met, but the J remained the same as before. Now along Bway Bkln, there were 2 S/B services, the J and M, and 1 N/B service, the K operating in the same physical direction but with opposite directional designations. Now the M is operating along 6 Av towards Continental and is back to being properly designated northbound lvg Met and southbound towards met, but the TA has not seen fit to redesignate the J back to its proper designation of northbound lvg Jamaica and southbound towards Jamaica even though it no longer operates in the Southern Division.