At three in the morning the Driscoll Bridge carries almost nothing, and the whole borough goes as quiet as it ever gets — just the hiss of falling snow finding the streetlights. That is the hour BK Snowplowing L.L.C. works in, pushing driveways and walks open across Sayreville so the first car of the morning rolls out onto bare pavement. Plowing here means knowing where the wind stacks a drift against a garage door and where the salt has to go before the melt refreezes at daybreak. There is a plain satisfaction in a driveway squared off at the corners, the apron cut back to blacktop, the path to the front step wide enough for two people to pass. Come daylight it looks like nothing ever happened, which is exactly the point.