Any tree or shrub which overhangs any public sidewalk or street in such a way as to impede traffic or travel on such sidewalk or street shall be trimmed by the owner of the abutting premises so that the obstruction shall cease. Any tree or limb of a tree which shall become likely to fall on or across any public walk or way shall be moved by the owner of the abutting premises. The superintendent of public works is hereby authorized to trim any such tree or shrub in any parkway, or to remove any shrub or tree which obstructs traffic or travel or which endangers persons traveling on such parkway. (1928 Code §102)