The impact of overhead wiring on the landscape is both physical and aesthetic. The widespread use of trees along streets as a design element presents problems to the electrical distribution network, since ultimately many trees come in contact with the overhead wiring, causing interruption in the delivery of electricity which becomes a safety issue. Even the practice of using proper arboriculture pruning techniques has often led to a degradation in the form of the street trees and has encouraged development of misshaped and aesthetically unpleasing trees.

Species selection, planting location, and cultural practices all have an impact on the ultimate visual quality, health, and cost of maintaining a street tree (1). Study of existing examples of street tree plantings allows for the development of design recommendations with appropriate species that will tolerate roadside conditions, reduce municipal infrastructure damage, and limit the interface between utility wires and individual trees.

The development of these recommenda-tions is based on street type, street width, size of tree belts, design intent, and the location of the physical infrastructure. The use of a standard set of criteria can ensure that a street tree will be able to develop to its desired shape, fulfill its design intent, and be aesthetically appropriate without interfering with overhead utilities, damaging the municipal infrastructure, or increasing maintenance costs.

Through the use of a set of standard roadway types, an effective mechanism for determining the relationship between street trees, design intent, municipal infrastructure and electrical distribution is possible. Harris and Dines (2) group roads and streets into four categories as the basis for creating a set of standard street types. These include Major Arterial, Minor Arterial, Collector, and Local streets.

When replacing street trees in a Major Arterial Road, for example, informed planting decisions can be used as the basis for recommendations for other street types. There are several alternative planting procedures that can be implemented to allow for increased visibility of the streetscape trees and improved aesthetic quality. These alternatives include the following:

1. Proper species selection, so that only trees that will not interfere with overhead utility lines, buildings and sidewalks are planted along streets. For example, with utility lines, one would want to plant a tree that grows no more than 25' above one's head (i.e. crabapples and other ornamental trees).

2. Setback planting of street trees to a location where they can grow without interfering with the overhead utility lines, buildings, and sidewalks.

3. Planting trees in locations within the right of way other than directly below the utility lines, including construction of new planting islands along the street edge.

This design system can serve as the basis for proper species and site selection. Through the development of a series of street type criteria, ranging from larger Major Arterial Roads to smaller Local streets, a workable and useful methodology is available to municipalities and utility companies for aiding in the selection and management of street trees. By incorporating physical factors with aesthetic and design considerations, this method can be an effective tool in the development of streetscapes that are less costly to maintain, are functionally more successful, and are aesthetically pleasing. LASN