1996 Local Street Tree Plan - Laserfiche WebLink

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TRAFFIC CALMING In many established neighborhoods throughout the City, excessive traffic speeds and volumes are a common source of complaint. In recent years, the City has begun to employ various techniques to slow traffic and/or shift traffic to more appropriate routes. These techniques are commonly referred to as "traffic calming" measures. Traffic calming concepts were first employed in Germany, Holland and Australia several decades ago. Over the past twenty years, an increasing number of cities throughout Europe, Australia, and the United States have used a variety of traffic control devices to improve street conditions in residential neighborhoods. Some of these devices are best employed in existing neighborhoods to address unsafe or undesirable conditions; others can be designed into streets when they are constructed to prevent or minimize the development of future problems. Table X indicates which techniques are suitable in each of those conditions. In existing developed areas, traffic speed and volume issues are sometimes slow to develop. Frequently, residents are able to tolerate the infrequent speeding vehicle, as long as traffic volumes remain low. However, as the city grows, residential areas which were once at the outer limits of the developed area, are affected by traffic generated from developments which are even further out. This plan proposes adoption of standards for applying traffic calming measures in established neighborhoods when it is likely that existing streets will be impacted by nearby new development. **QUESTION: SHOULD TRAFFIC CALMING IMPROVEMENTS TO EXISTING STREETS BE REQUIRED AS OFF -SITE IMPROVEMENTS FOR NEW DEVELOPMENT THAT IMPACTS EXISTING NEIGHBORHOODS? Traffic calming measures can also be employed in the construction of new streets to prevent problems from developing in newly constructed or future residential areas. To date, traffic calming measures have been applied only on existing public streets in established neighborhoods. The techniques discussed below » »» Traffic Circles. Traffic circles ( also called "roundabouts ") are raised landscaped islands placed in the center of an intersection. Their primary purpose is to reduce speed and to separate intersection conflicts. Circles are especially effective in a series and may reduce through- traffic on streets where they are used. Traffic circles are typically used on relatively low - volume residential streets and require reflectors and appropriate signing. The recommended design standard for traffic circles consists of a set of two concentric rings. The outer ring is a mountable curb and is 23' in diameter. The inner ring is elevated above the outer ring, is 16' in diameter, and includes a vertical 6" curb. The two rings are connected by an area of sloping pavement. The center area may be paved or landscaped; landscaping is preferred for its aesthetic value. Traffic circle landscaping involves consideration of irrigation and long- term maintenance. These issues should be resolved before landscaping is chosen as the preferred option.