On MA 3A (Plymouth) I would suggest putting a point at the intersection of Southern Artery (or Merrymount Parkway) and Hancock Street. Had I not overridden the GPS I would've missed the bypass altogether because the GPS took us down Hancock and Washington through downtown Quincy. This could happen to other people too, either by GPS or because they wanted to go to downtown Quincy.
42.2620/-71.0116