§ 3. Subdivision design standards and requirements.
3.1
Relation to adjoining street system. The arrangement of streets in new subdivisions shall make provisions for the continuation of the principal existing streets in adjoining areas or their proper projection where adjoining land is not subdivided, insofar as the commission may deem the continuation of the existing street necessary for public requirements. Offset streets should be avoided but if unavoidable shall be offset by at least 125 feet. The angle of intersection between minor streets should not vary by more than ten degrees from a right angle. Streets obviously in alignment with existing streets shall bear the names of the existing streets. All proposed street names shall be checked against duplication of other street names. The widths and locations of major streets shall conform to the widths and locations designated on the comprehensive plan and in conformance with the street specifications. Other design criteria including sight distances, medians, driveway spacing, traffic control and intersections shall conform to the access management manual.
3.2
Design standards.
a.
Street design standards.
Design Subject Minimum Right-of-Way Width Minimum Pavement Width Maximum Grade (1) Major Streets: Arterials 80 feet 49 feet 5% Collectors 66 feet 38 feet 8% (2) Minor Streets: Residential 50 feet 32 feet 10% Industrial 60 feet 32 feet 6% Commercial 60 feet 32 feet 6% (3) Culs-de-sac (diameter) 100 feet 76 feet 6% (4) Frontage Roads 60 feet 32 feet 8% (5) Low Volume Residential 50 feet 28 feet 8% (Estate/Cul-de-sac streets with low volume traffic) (6) Alleys (nonresidential) 20 feet 16 feet 10% (7) Minimum radius of street intersections at a ninety-degree angle: Arterial streets 30 feet Collector streets 30 feet Minor streets 20 feet (8) Minimum sight distance on vertical curves: Arterial streets 250 feet Collector streets 200 feet Minor streets 150 feet (9) Maximum degree of centerline curvature: Arterial streets 7°—30′ Collector streets 12°—30′ Minor streets 57°—29′ (10) Length of terminal streets requiring a cul-de-sac: Minimum 200 feet Maximum-Normal 750 feet Maximum-Special 1,600 feet* *In order to promote developments featuring large lot size, low density of traffic and units, privacy and retainage of natural features, the commission will consider, at a minimum, the following points in deciding whether or not to allow the length of a terminal street to exceed 750 feet as measured from the center of the cul-de-sac to the right-of-way of the nearest through street from which it derives.
i.
Topography: When construction of a loop return street from the proposed terminus to an intersecting cross street would require building through terrain with steep slopes, ravines, bluffs or swamps so as to result in a cost greater than could be retrieved by the sale of the poor lots along its length.
ii.
Lot size and arrangement: Size of lots exceed one acre and minimize the number of lots with rear lot lines abutting a neighbor's rear line.
iii.
Configuration of development: Where the area to be developed of a given plat is such that the length is greater than the width by a minimum ratio of four to one.
iv.
Phased development: When a developer decides to build and sell lots of a portion of a development in a series of phases, then any streets at the completion of a given phase, which may end temporarily as terminal streets, shall require a temporary cul de sac.
b.
Lot and block design standards.
(1) Maximum block length: Residential area 1,000 feet Industrial area 1,500 feet Commercial area 1,000 feet (2) Minimum block length: Residential area 400 feet Industrial area 400 feet Commercial area 300 feet (3) Preferred block length: Residential area 750 feet Industrial area 1,000 feet Commercial area 600 feet (4) Minimum lot depth 100 feet (5) Minimum easement width 10 feet 3.3
Character of development.
a.
The commission shall confer with the subdivider regarding the type and character of development that will be permitted in the subdivision and may agree with the subdivider as to certain minimum, restrictions to be placed upon the property.
b.
Where the subdivision contains streets, sewers, sewage treatment plants, water supply systems, park areas, street trees or other physical facilities necessary or desirable for the welfare of the area and which are of common use or benefit and are not or cannot be satisfactorily maintained by an existing public agency, provision shall be made for the proper and continuous maintenance and supervision of such facility by a private or quasi-public agency, group or business. Such provision shall be made legally binding and shall be approved by both the city and other agency having jurisdiction over the location and improvement of such facilities.
3.4
Parks, school sites, etc. Where an area being subdivided includes lands proposed to be used for parks or schools, under the duly adopted comprehensive plan of the city and environs, the subdivider shall not plat such lands as a part of the subdivision plat; and shall confer with the appropriate public agency regarding the time, method and amount of payment for the agency to acquire the land. If no agreement has been reached upon the acquisition of the area within two years from the date of the submission of the preliminary plan, the subdivider may then plat the balance of the area.
3.5
Easements along streams. Whenever any stream or important surface drainage course is located in an area, which is being subdivided, the subdivider shall provide an adequate easement along each side of the stream for the purpose of maintaining, widening, deepening, sloping, improving, or protecting the stream or drainage course.
3.6
Sidewalks. Sidewalks shall be installed on both sides of major streets. They shall be installed on at least one side of a minor street in residential districts as zoned by zoning ordinances of the city. The commission may also require sidewalks where, in its judgment, the public interest requires it. The sidewalk specifications provide drawings of standards giving dimensions, grades, and geometry of typical sidewalk and driveway details.
a.
Refer to sidewalk specifications maintained by the director of public works and revised and adopted December 2008 and revised July 2011.
b.
Sidewalks shall be placed within the street right-of-way and shall be generally aligned and parallel to the edge of the right-of-way. Curved sidewalks may be necessary to accommodate topography and will be considered on a case by case basis. Sidewalks will be shown on the final plat.
3.7
Streets: Private. Private streets or roads are not favored and shall be permitted only when it is shown to the satisfaction of the commission and city council that no public interest would be served by a public street or road. Private streets shall be designated to allow for the necessary mobility of public service and safety vehicles.
In the event adjoining landowners of a private road request the city to accept dedication of the private road, the city shall not accept the public dedication until the private road is improved to meet current minimum street construction standards. Properties annexed having private roads would be grandfathered in although the owner would continue to be responsible for maintenance and repairs. If property is to be further developed in the future, the plan must be submitted, which may require higher road standards.
(Ord. No. 4059, § 3, 8-16-07; Ord. No. 4262, § 2, 8-1-11)