§ 34-485. Street plan

(a) Generally.

(1) The arrangement, character, extent, location and grade of all streets shall be laid out according to good land planning principles and shall be integrated with all existing and planned streets. New streets shall consider topographical conditions, orientation to vistas, public convenience and safety and the proposed uses of land to be served by them.

(2) The proposed street system shall also be coordinated with the street system of the surrounding area. However, the number of streets converging upon any one point which would tend to promote congestion shall be held to a minimum. Creation of street intersections of three or more streets shall not be permitted. The street pattern shall be in conformity with a plan for the most advantageous development of the entire neighboring area.

(3) Sufficient proposed streets shall be provided to create normal circulation of traffic within the vicinity. Land abutting a proposed subdivision shall not be left land-locked by such proposed subdivision. Street design shall provide connections to abutting properties at intervals not to exceed the maximum block length of 1,800 feet.

(4) In addition, if, in the opinion of the planning commission, it is desirable to provide street access to an adjoining property, said street shall extend by dedication to the boundary of such property. A temporary turnaround, as defined in design standards for a street cul-de-sac, shall be provided for these streets. Minor streets shall be so laid out that their use by through traffic in the subdivision will be discouraged.

(5) Subdivisions which abut or have included within the proposed area to be subdivided any freeway or major street as shown on the county thoroughfare plan shall be platted in the general location and of the width called for by such plan. In addition, any such subdivision shall also provide the following:

a. A marginal access street,

b. Reverse frontage with screen planting contained in a non-access reservation along the rear property lines,

c. Deep lots with rear service drives, or

d. Other treatment which may be necessary to provide for the adequate protection of properties, and to afford separation of through and local traffic.

(6) Intersections of minor subdivision streets with major streets shall be held to a minimum.

(b) Half streets. Where there exists a dedicated or platted half-street adjacent to the tract to be subdivided, the other half shall be platted. New half streets or half alleys shall be prohibited.

(c) Culs-de-sac. Streets designed to have one end permanently closed shall be provided at the closed end with a turnaround having a minimum right-of-way diameter of 100 feet, and a minimum roadway diameter of 80 feet. Where the cul-de-sac is expected to be continued in the future into unsubdivided land, the turnaround may be a temporary one.

(d) Intersections. Street intersections with centerline offsets of less than 125 feet shall not be permitted.

(e) Minimum right-of-way widths.

(1) In developed or vacant areas, the planning commission shall have the discretion of identifying or classifying streets.

(2) The widths of rights-of-way for the various streets (major streets, collector streets, minor streets and alleys) are indicated below. Widths shall be not less than the following:

Street Type	Right-of-Way
Major streets	As required by the state department of transportation or county commissioner
Collector streets	50 feet
Minor streets and culs-de-sac	50 feet
Alleys	40 feet
Marginal access	(included in right-of-way of arterial)

(3) In cases where topography or other physical conditions make a street of the required minimum width impracticable, the planning commission may modify the above requirements. Through proposed neighborhood or local business areas, the road widths shall be increased ten feet on each side to provide for movement of vehicles into and out of necessary off-street parking areas without interference to traffic.

(4) Subdivisions that adjoin existing roads shall dedicate additional right-of-way to meet the above minimum right-of-way width requirements, and:

a. The entire right-of-way shall be provided where any part of the subdivision is on both sides of the existing road.

b. When the subdivision is located on only one side of an existing road, one-half of the required right-of-way, measured from the centerline of the existing roadway, shall be provided.

(f) Minimum roadway widths. The minimum pavement widths for the various classifications of streets shall be as follows:

(1) Major streets. As required by the state department of transportation or county commissioner (measured from pavement edge to pavement edge with curb and gutter).

(2) Collector streets. With curb and gutter, 28 feet.

(3) Minor streets and culs-de-sac. With curb and gutter, 24 feet.

(4) Alleys. With curb and gutter, 18 feet.

(g) Street grades.

(1) Street grades shall not exceed the following, unless otherwise recommended and approved by the commissioner:

a. Major streets. As required by the state department of transportation or the county commissioner.

b. Collector streets. Not to exceed 18 percent greater than 300 feet and ten percent for the remainder.

c. Minor streets and culs-de-sac. Not to exceed 18 percent greater than 300 feet and ten percent for the remainder.

(2) Grades approaching intersections shall not exceed five percent for a distance of not less than 100 feet from the centerline of said intersection.

(3) Minimum grades of all roadways shall not be less than five-tenths percent.

(4) Surface cross-drainage shall not be permitted on any street.

(5) Vertical curves shall be constructed so as to afford a minimum sight distance being measured from the driver's eyes (4½ feet above pavement surface) to an object four inches high on the pavement surface.

(h) Alignment and visibility.

(1) Horizontal curvature. The minimum radii of centerline curvature shall be as follows:

a. Major streets. As required by the state department of transportation or the county commissioner.

b. Collector streets.150 feet.

c. Minor streets and dead-end streets and alleys. 75 feet.

(2) Tangents.

a. Major streets. As required by the state department of transportation or the county commissioner.

b. Collector streets. Fifty feet.

(3) Vertical alignment.

a. Major streets shall have a sight distance of at least 300 feet at six feet above ground level.

b. Collector streets shall have a sight distance of at least 150 feet at six feet above ground level.

(4) Intersections. Street intersections shall be as nearly at right angles as possible. No street intersection shall be an angle of less than 60 degrees. Submission of a grading plan showing existing conditions and a detailed design for intersections which are unusual or located on difficult terrain may be required by the planning commission.

(5) Sight lines. Minor and collector streets shall have a clear sight triangle of 75 feet (150 feet for major streets) from the point of intersection, and this shall be indicated on all plans. No buildings or other obstructions between three feet and 15 feet in height shall be permitted in this area.

(6) Curbline radius. The curbline radius at street intersections shall be at least 15 feet. Where the angle of street intersection is less than 90 degrees, a longer radius may be required.

(i) Alleys.

(1) Alleys may be required in commercial and industrial districts, except that the planning commission may waive this requirement where other definite and assured provision is made for service access, such as off-street loading, unloading and parking facilities consistent with zoning requirements.

(2) Alleys are not permitted in residential districts, except when the planning commission determines special conditions warrant a secondary means of access.

(j) Names.

(1) No street name shall be used which will duplicate by spelling or sound, or otherwise be confused with the name of existing streets. Street names are subject to the approval of the planning commission.

(2) Subdivision names and apartment project names shall not duplicate or be confused with existing names and are subject to approval by the planning commission.

(k) Department of transportation certificate of approval. State department of transportation certificates of approval must be included for the proposed project, if the project abuts any state, federal or county property.

(Ord. of 7-20-1994, § 9.15)