Two in the morning on Ocean Avenue, and the only things moving are the streetlights swaying and a truck with its blade down. Property Masters, Inc. keeps Portland properties open through the winter — plowing lots and driveways, clearing walks and entries, and sanding or salting once the surface is down to pavement. Commercial and residential ground both come with a deadline the weather sets and nobody can move. The job is finished when the first person of the day arrives and finds nothing in their way. Winter work reaches across Portland into South Portland, Westbrook, Falmouth and Scarborough.