Winthrop St. Bridge Snow Removal

Why does the city NEVER clear the sidewalks on the Winthrop St. bridge over the train tracks? Snow and ice pile up and people have to walk in the middle of the street to avoid it. It's only a matter of time before someone is hit and killed by a car. When you call DPW, all they can say is "We'll put in a report". This is completely unacceptable.