Paste in arrow geometry from another file. If these are not already created, create, make them separately in another file for to re-use later. Create Shark's teeth and whatever other markings are necessary. The curving parts of the sidewalks can go to a LOD that is far less smooth in a very short distance. This will reduce the polygon load by perhaps two thirds.
Islands can do the same.
Use a circle with less sections to create points for a new, simpler stripface curb. Broken lines can turn into a single line. Shark's teeth can turn into a single line that is somewhat thinner than they are. Arrow can have fewer polygons but still represent the basic shape. 9.Determine where features will go, place construction points to mark these places.