Had a problem with the city of LA a few years ago. They promised to cut their tree several times but didn't show up for more than a year. Finally I called and told them about a hanging broken branch and the fact that there were many children in the area. They came out in 2 days.
If the tree is in the fairway (the part between the sidewalk and the street) it is their property but maintenance is usually left to the resident (which is a hidden tax on the resident) yet they have the right to fine you if they don't like what you do.
Sometimes they will trim a tree if it actually interferes with truck traffic on your street.
I suggest you get a tree trimmer on a weekend day, cut it back to the sidewalk.
