I previously reported that CN 148 and 149 don't come to the Maritimes any more. Courtesy of the Atlantic Northeast Rails & Ports newsletter, here are a few more details.
What used to happen is that CN 148 would leave Chicago and arrive in Halifax at 08:35, 3 days after departure. Now CN 148 terminates in Montreal. Traffic destined for Halifax is left in Toronto and picked up by CN 120, which is due into Halifax at 06:45 saving 2 hours of time over the old schedule. CN 122 departs Montreal at 03:00 and is scheduled to arrive in Halifax at 06:30 the next day.
The main advantage of this plan, beyond the 2 hour time saving, is that a Montreal-Halifax train is more consistent than a Chicago-Halifax train. A train going over a shorter distance is less likely to be late!
120/121 should definitely increase in length and 122/123 will be shorter than the old 148/149.
It'll be interesting to see how this plays out.
EDIT: for much more detail on the changes, please contact Chalmers (Chop) Hardenbergh, editor of Atlantic Northeast Rails & Ports at 207-846-3549 or email@example.com.