All dead-end streets are operated two-way and should be wide enough to permit turning around. If the street is wide enough, a dead-end can be made simply by providing a barricade across the street, possibly with a curb in front of it, supplemented by adequate warning signs and markers. Streets terminated by freeways or other arterial highway construction or by steep terrain are not likely to be sufficiently wide, in which case their ends should be altered to enable vehicles to turn around.
New subdivisions or private streets should always be required to provide a turning area. The Streets Dimension Standard Plan (Standards S-470-1) again, shows cul-de-sacs and alley turning areas. Where unusual conditions prevail, modifications of the turning area like those shown on this figure may be made. However, these altered shapes must provide equivalent minimum turning space.
(Referring to Figure E 113 again, the turn-around curb radius for all cuI-de-sacs is a minimum of 35 feet.)1 Referring to the Streets Dimension Standard Plan (Standards S-470-1) again, the turn around curb radius for all cul-de-sacs is a minimum of 35 feet. In all cases in which industrial zoning prevails, the curb radius for the cul-de-sac turning area is a minimum of 50 feet. Upon entering a cul-de-sac, a motorist encounters a length of curb radius which is tangent to the normal street curb and forms a reverse curve with the turn-around curve. The radii of these lengths of curve are a minimum of 50 feet. The border width should be maintained around the cul-de-sac configuration on new streets, and on existing streets where feasible. This border width is to be used only where abutting property is to be serviced. However, on existing streets, a minimum of a 6-foot wide border may be provided. For example, if a sidewalk is included as a part of the border, it must be a minimum of 6 feet in width. Obviously, if a 6-foot-wide border includes a sidewalk, it would consist entirely of sidewalk.
However, a border could be 10 feet wide and have a 4-foot sidewalk and a 6-foot parkway. The reasoning behind this is that the minimum “Y” distance of a driveway apron is 6 feet to allow modern cars to negotiate the driveway. Only with prior special approval of the City Engineer should deviations from these criteria be made.
Footnotes
1The text in parenthesis is from the legacy Street Design Manual text and has been superseded by the italicized text that follows.
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