Gratiot runs through Chesterfield straight as a ruled line, and in a January before dawn it is mostly plow lights and empty lots. Glass Block Concepts clears snow across that stretch — drives, lots, and the approaches that have to be open before the first car arrives. Weather off Lake St. Clair comes damp and heavy, the kind that packs down and locks up if it is left alone. Getting ahead of it, pass after pass, is the difference between a lot that works at six in the morning and one that does not. There is a quiet good feeling in leaving bare pavement behind you and moving on to the next address.