Where the Saugus River widens into marsh at the western edge of Lynn, a nor'easter arrives sideways and the flat industrial lots catch the whole of it. Northeast Transport & Snow Services Inc plows that kind of ground: long open pavement, truck aprons, gate lines that have to stay usable while the storm is still going. Wet coastal snow is heavy and sets up like concrete once the temperature drops behind the front, so it gets moved early and moved again. Walks and entryways are shoveled and salted so the first person through the door has bare footing. When a business opens on time the day after a foot of snow, somebody was out there at four.