Check out the B&A track chart at www.zekedev.com/sites/boston_line/index.cfm, an excellent source of information provided most generously by its owner. From my review, it appears that 1.52% eastbound (in Dalton) and 1.65% (Chester) westbound are the maximum grades, with other westbound grades of 1.61% (Middlefield); 1.60% (Washington) and 1.55% (Becket) rivaling the relatively short section in Chester.