When sleet rides in over the Acushnet River and the bridge to Fairhaven goes slick, New Bedford stops being a driving city for a few hours. Tip Top Tree Service works exactly those hours — plowing driveways and lots, shoveling steps and walks, spreading salt where freeze-and-thaw would otherwise win. Storms off the water tend to run wet and heavy, so a driveway gets cleared and then cleared again once the town plow buries the end of it. Reaching a genuinely clean surface, not merely a passable one, is the standard the night is judged by. By sunrise the pavement is dark again and the day works.