Freight in San Francisco Article

A couple months ago Trains Magazine had a feature story on the last freight operation in San Francisco. I was just out there and decided to visit the location and indeed found the crossing on Quint Street. The article mentioned Caltrain and the UP freight trains. Imagine my surprise when I saw no trespassing signs along the right of way posted by BURLINGTON NORTHERN SANTA FE. What are they doing in that area of San Francisco ? I didn’t know they were even in the City anymore. Do they own that track being used by UP or has someone decided to recycle some old BNSF signs ?