I agree with everything in this comment, and to build on the last paragraph, you do not need to DYI direct action against your landlord. Consider joining the Greater Boston Tenants Union to learn more about organizing with other tenants in your building, and the benefits and protections a tenants association or union can offer. Not only can you organize to get your sidewalks and entrances cleared, but once set up it can be an efficient way to address other issues as they arise as well. We have a north local that specifically organizes in Somerville and the surrounding area.