The beleaguered MBTA chugged through the Blizzard of 2018 with only minor complications yesterday — a remarkable wintertime feat for the aging agency — but braced for a crush of commuters that could test its limits even further as it resumes normal service today.“I would say in general the MBTA did a good job of getting a much smaller group of riders than usual where they wanted to go today,” said MassDOT Secretary Stephanie Pollack.