The purpose of sidewalk buffers, also called planting strips, is to isolate pedestrians from moving motor vehicles, where parking does not provide a sufficient buffer. Sidewalks adjacent to the curb are called attached sidewalks, while sidewalks with a buffer are called detached sidewalks.
Traditionally all residential, collector, and arterial streets had buffers. Retail areas often did not, in order to make getting from the car to the sidewalk more convenient.
Modern suburbs, however, usually eliminated the buffer strip from all streets in order to maximize the area available for development and roadways. Pedestrians do not like to walk next to fast traffic. In part, the elimination of buffers is why there is much less walking in the suburbs. The lack of buffers also makes an area look harsh, with a bland expanse of pavement rather than the welcoming and beautiful strip of nature. The planting strips and their vegetation require maintenance, and responsibility for those areas is another question of responsibility.
This diagram above shows a typical sidewalk cross-section for a mixed/multi-use street. The sidewalk buffer is here called the furniture zone. This particular type of street is described in the Model Design Manual for Living Streets as “The sidewalks along these streets should support significant pedestrian volumes due to their integrated nature and higher densities. Of the four sidewalk zones, the pedestrian and frontage zones will be favored. Transit service runs along these streets and sidewalks will require buffers from traffic.” There are nine street settings described in this manual, with diagrams for five of them.
In downtown Sacramento, many streets do not have sidewalk buffers, however, they do have very wide sidewalks, up to 24 feet in a few places, which create the same isolation from motor vehicle traffic that sidewalk buffers do. In parts of downtown and much of midtown both residential and mixed use streets have sidewalk buffers. It is not until one gets out to the first ring suburbs that the buffers start to disappear, and the new suburbs beyond have almost completely lost them. It feels different!