The main goal of a street tree ordinance is to shade pedestrians, but shading park cars is a side benefit. However, these trees, variegated Pittosporum tenuifolium (witch hazel family), litter the sidewalk with seedpods (just cleaned by maintenance crew), so are not a good choice. Here on a street with businesses on either side, trees have been planted as close to the street as possible. One can only guess at the intent, but a basic tenet of traffic calming is placing trees close to the street. Trees, plus parked cars on both sides of the street is a kind of double street-calming scenario, although some drivers still speed through.

Small Towns
Many small communities, be they villages, hamlets or even designed new urbanist communities, often do not have traditional, detailed zoning ordinances, but they do have municipal code of ordinances. Take Pass Christian ("The Pass"), Mississippi (pop. 4,613), for example. Note: The name derives from French explorers dubbing the channel off the peninsula "Passe aux Hu?????tres" (oyster passage). This quaint, little community (15.3 sq. miles) on the shores of the Gulf Coast in Harrison County near New Orleans, adopted the SmartCode after Hurricane Katrina roared through. The city fathers implemented this New Urbanism zoning code as a means to rebuild from the storm's devastation. The Pass has a tree ordinance, but no landscape code. The landscape standards of the SmartCode are not adequate, but they do move in the right direction, in that it provides for street trees. However, the purpose of street tree plantings in the code is not clear.

What is needed for a small community is a simple tree ordinance that provides not only tree planting standards for public streets, but design standards for street tree planting areas, and street yard buffers composed of yard trees.

Shading the Sidewalk
There is an answer to this small town quandary. It is a simple sidewalk shading ordinance that not only regulates sidewalks but provides shade trees. This is an ordinance not only needed in small towns, but larger cities as well.

Street trees are not provided for drivers. Trees are not on drivers' minds when their goal is to get from point A to point B. Certainly trees provide visual relief for those driving, but the real purpose of street trees is to provide shade for sidewalks.

Shading Sidewalks
Street trees have been used for shade since their adoption in Roman times for pedestrians and horsemen. We know that Via Appia (the Appian Way) was built with sidewalks sometime after 312 B.C., so it is logical to assume that roadside trees were preserved or even planted to provide relief from the sun's rays.

Community shade tree ordinances encourage people to get outside and walk, bike, jog or even socialize with neighbors. And well-shaded sidewalks better separate pedestrians from city traffic. It is shade on the sidewalk that is needed, not tree lined roadway edges. Editor's note: A basic tenet of traffic calming, however, is placing trees next to streets.

Sidewalks Shading Ordinances The essential sections of any sidewalk shading ordinance include the policy, purpose and authority statement; definitions; use of right-of-way; sidewalk construction specifications; landscaping-street trees; and miscellaneous concerns such as violations, penalties, public liability, severability and adoption.

The most critical sections of sidewalk ordinances are shading specifications, street tree selection and planting location. A sidewalk ordinance must set a shade standard. The designer must control the pattern and extent of shade. This is done through species, selection, sizing and proper spacing. It is suggested that a minimum of 40 percent canopy coverage after 15 years of growth is appropriate. Shading is measured by the projected diameter of the tree crown. With the use of class B trees with a 30-foot diameter, a 90 percent shade standard can be designed.

Tree species ought be carefully selected for planting in tight urban street tree planting areas. Class A trees (50-ft. diameter of tree crown) is not always the best choice. Choose smaller trees with small fibrous root systems and that will thrive in dry urban conditions. Always select trees for texture, fall color, flowers, light fruiting and that will withstand storms.

Tree planting should take place on the outside edge of the right-of-way if possible, and not between the sidewalk and the curb if it can be avoided. Class A trees, the usual native over-story tree of the community, should be planted within the "street garden" of adjacent properties. These trees, known as yard trees, are to be planted on private property. They should be furnished by the city since their purpose is public yet maintained by the private property owner. Large trees that shade sidewalks must be on private property and a private-public agreement must we worked out to allow this to occur. And, of course, trees must not be spaced too close together.

Landscape Laws and Trees
A quick review of the Los Angeles Municipal Code (American Legal, Chapt. I, IX, Art 2, Art. 7 and Art. 9 and Sec. 12.40-12.43), including design standards, building regulations, landscape code and green building practices, revealed no sidewalk shading requirements for street trees. So it is easy to see that even large communities fail to see the importance of sidewalk shading.

For an outline for a sidewalk shading ordinance contact the author by email: lsugreenlaws@aol.com. You may also call Abbey Associates Landscape Architecture at (225) 766-0922.