106-IV DESIGN STANDARDS

ARTICLE IV. DESIGN STANDARDS

106-126 General standards.

All subdivisions shall be so designed to conform to the master plan, the zoning ordinance, this chapter, the subdivision act, any and all current specifications, standards and requirements for the development and improvement of the city, and to the public acts of the state.

(Code 1985, § 24-12)

106-127 Streets.

(a) Generally. Streets shall conform to at least all minimum requirements of the general specifications and typical cross sections as set forth in this article, as amended from time to time, and other conditions as set forth by the city.

(b) Street locations and arrangements.

(1) Street layout shall provide for the continuation of existing major or urban thoroughfares and collector streets in adjoining subdivisions and when adjoining property is not subdivided for the proper projection of streets; or conform to a plan for a neighborhood unit when drawn and adopted by the planning commission.

(2) Major or urban thoroughfare locations and arrangements shall be designed as generally indicated by the master thoroughfare plan and determined in detail by the city engineer.

(3) Where a proposed residential subdivision abuts or contains an existing or proposed major or urban thoroughfare or railroad right-of-way, the planning commission may require marginal access streets, reverse frontage or such other treatment as may be necessary for the adequate protection and stabilization of residential properties and to afford separation of through and local traffic.

(4) Where a proposed residential subdivision abuts or contains a collector street, the planning commission may require reverse frontage on the abutting property or that abutting lots possess an orientation toward a minor residential street.

(5) Minor residential streets shall be so arranged as to discourage their use by traffic not destined for a location within the subdivision.

(6) Alleys shall not be platted in residential areas. The planning commission and engineering division shall have the right to determine the need for alleys in commercial and industrial areas.

(7) Half streets shall be prohibited, except where absolutely essential to the reasonable development of the subdivision in conformity with the other requirements of this chapter, and where the planning commission finds it will be practicable to require the dedication of the other half when the adjoining property is developed. Wherever there exists adjacent to the tract to be subdivided a dedicated or platted and recorded half street, the other half shall be platted.

(8) Street jogs with centerline offsets of less than 125 feet shall be avoided.

(1) Street right-of-way and pavement widths shall not be less than those indicated on the master thoroughfare plan of the city and in this chapter, as amended from time to time, and shall be determined in detail by the city engineer. The master thoroughfare plan and this chapter’s standards, at present, are as follows:


	Street Type	Right-of-Way (feet)	Pavement Width (feet)
a.	Expressway or super highway	200 to 250	As determined by the city engineer
b.	Major thoroughfare (major arterial)	90 to 120	As determined by the city engineer
c.	Urban thoroughfare (minor arterial)	90	As determined by the city engineer
d.	Collector street	86 to 90	48 to 50
e.	Minor residential street	60	30, parking allowed on one side
f.	Multiple-family residential street	60	30, parking allowed on one side
g.	Cul-de-sac turnaround	60 minimum outside radius	30 minimum 47 outside pavement
h.	Loop street	60	30
i.	Marginal access service drive	50	30
j.	Alley	25	18 minimum

(2) Maximum length for residential cul-de-sac streets shall be 500 feet. Maximum length for industrial cul-de-sacs may exceed 500 feet, subject to planning commission approval.

(d) Street geometrics.

(1) Major thoroughfares, urban thoroughfares and collector streets shall not have a grade greater than five percent, or as approved by the city engineer. Minor residential streets shall not have a grade greater than six percent, or as approved by the city engineer.

(2) Major or urban thoroughfares shall have a minimum stopping sight distance and passing sight distance as established by American Association of State Highway and Transportation Officials’ Standards based on the design-speed. Such standards are on file with the city traffic engineer.

(3) Collector streets shall have a minimum stopping sight distance of 200 feet for a design speed of 30 miles per hour measured between an observer at a height of 3.75 feet and an object at a height of six inches. Appropriate minimum increases shall conform to American Association of State Highway and Transportation Officials’ Standards.

Minor residential streets shall have a minimum stopping sight distance of 200 feet, measured between an observer at 3.75 feet and an object at six inches.

(4) Horizontal alignment: When tangent centerlines deflect from each other, a minimum stopping sight distance based on American Association of State Highway and Transportation Officials’ Standards and Design Speed shall be maintained. There shall be a sufficient tangent distance to allow acceptable transition from one curve to the adjacent curve.

(5) A 25-foot area of clear vision at intersecting curblines on each street in subdivisions shall be provided. This area shall be kept clear of all structures and vegetation exceeding a height of three feet above the curbline.

(6) Streets shall be laid out so as to intersect as nearly as possible to 90 degrees. In no instance shall streets intersect at an angle less than 70 degrees.

(7) Curved minor residential streets intersecting a collector, major or urban thoroughfare shall do so with a tangent section of centerline not less than 50 feet in length measured from the right-of-way line of the collector, major or urban thoroughfare. This requirement may be waived, however, when the curve of the minor residential street has a radius greater than 400 feet, with the center of the curve located on the right-of-way line of the collector, major or urban thoroughfare.

(8) Street corners on minor residential streets shall have a minimum radius of 20 feet at the curbline.

(9) Street corners on collector streets shall have a minimum radius of 25 feet at the curbline. Street intersections involving major or urban thoroughfares shall have a minimum radius of 25 feet at the curbline or as determined by the city engineer.

(10) Acceleration, deceleration and passing lanes shall be provided as determined by the traffic safety committee, according to normal traffic engineering practice, in order to prevent the obstruction of the free flow of moving traffic on all thoroughfares.

(e) Street construction and dedication.

(1) All streets will be dedicated to the city and shall be built to city specifications under direct city inspection, and according to the provisions of this chapter.

(2) Construction and inspection of streets shall be at the expense of the developer. Street construction shall include adequate storm drainage.

(Code 1985, § 24-13)

106-128 Blocks.

Blocks within subdivisions shall conform to the following standards:

(1) Maximum length for blocks shall not exceed 1,200 feet in length, except where, in the opinion of the planning commission, conditions may justify a greater distance. Minimum block lengths shall be 500 feet.

(2) Widths of blocks shall be determined by the condition of the layout and shall be suited to the intended layout. Generally, however, minimum block width shall be 200 feet.

(3) Location and construction of public walkways or crosswalks may be required by the planning commission to obtain satisfactory pedestrian access to public or private facilities, such as, but not limited to, schools and parks, and where blocks exceed 900 feet in length.

(4) Walkways shall be dedicated to the public or provided as a private easement for this purpose and shall be at least 12 feet in width.

(Code 1985, § 24-14)

106-129 Lots.

Lots within subdivisions shall conform to the following standards:

(1) The lot size, width, depth and shape in any subdivision proposed for residential uses shall be appropriate for the location and the type of development contemplated.

(2) Lot areas and widths shall conform to at least the minimum requirements of the zoning ordinance for the district in which the subdivision is proposed.

(3) Building setback lines shall conform to at least the minimum requirements of the zoning ordinance.

(4) Corner lots in a one-family residential subdivision shall be at least 15 feet wider than the minimum width required.

(5) Excessive lot depth in relation to width shall be avoided. A depth-to-width ratio of three to one shall normally be considered a maximum.

(6) Lots intended for purposes other than residential use shall be specifically designed for such purposes, and shall have adequate provision for off-street parking, off-street loading, and other requirements in accordance with the zoning ordinance.

(7) Every lot shall abut or front on a street.

(8) Side lot lines shall be at right angles or radial to the street lines, except where some variation is necessary to preserve natural features. Dogleg side lot lines shall be prohibited.

(9) Lots shall have a front-to-front relationship across all streets where possible.

(10) All residential lots abutting major or urban thoroughfares, where marginal access streets are not desirable or possible to attain, shall be platted with reverse frontage lots or with side lot lines parallel to such thoroughfares which shall be platted with reverse planting screen, mounds and/or berms contained within a nonaccess greenbelt reservation along the rear or side property line having a minimum width of 15 feet. The planting screen, mounds and/or berms shall be approved by the city forester, and grading of these reservations shall be approved by the city engineer.

(11) Where lots border upon bodies of water, the front yard may be designed as the waterfront side of such lot, provided the lot has sufficient depth to provide adequate setback on the street side to maintain a setback for all structures equal to the front setback on both the street side and the waterfront side.

(Code 1985, § 24-15)

106-130 Easements.

Easements within subdivisions shall conform to the following standards:

(1) Location of utility line easements shall be provided along the rear or side lot lines as necessary for utility lines. In instances where extreme topographic features or vegetation exists, easements may be located along the front lot lines to thus conserve natural features. Easements shall give access to every lot, park or public grounds. Such easements shall be a total of not less than 12 feet wide, six feet from each parcel.

(2) As per section 106-102(h)(1), all lines for power and communication facilities transmitted by wire or cable, including all individual service connections, shall be placed underground throughout the entire subdivision.

(3) Recommendations on the proposed layout of all utility easements, such as telephone and electric company easements, should be sought from all the utility companies serving the area. It shall be the responsibility of the proprietor to submit copies of the preliminary plat to all appropriate public utility agencies.

(4) All power and communication facilities shall be constructed in accordance with standards of construction approved by the state public service commission.

(5) Easements three feet in width shall be provided where needed along side lot lines, so as to provide for street light dropouts. Prior to the approval of the final plat for a proposed subdivision, a statement shall be obtained from the appropriate public utility indicating that easements have been provided along specific lots. A notation shall be made on the final plat indicating: “The side lot lines between lots (indicating lot numbers) are subject to street light dropout rights granted to the (name of utility company).”

(6) Easements needed for storm drainage, sanitary sewers and water mains shall be determined by the city engineer and shall meet the requirements of the city engineer.

(Code 1985, § 24-16)

106-131 Public reservations and dedications.

The subdivider shall provide sites for public parks, public schools, fire stations or other public uses when such uses are wholly or partially located within the proposed subdivision, as indicated on the master plan. The approximate size and general location of the site for such a public facility shall be determined by the planning commission in accordance with accepted planning standards and principles. Sites required under this chapter shall be provided by one of the following methods:

(1) Dedication to the city or the school district.

(2) Reservation for acquisition by the city school district within a period of three years. Such reservation shall be made in such a manner as to provide for a release of the land to the subdivider in the event that the city or the school district does not proceed with the purchase during such period of three years.

(Code 1985, § 24-17)

106-132 Environmental conditions.

Environmental conditions within subdivisions shall conform to the following standards:

(1) Floodplains. Any areas of land within the proposed subdivision which lie either wholly or in part within the floodplain of a river, stream, creek or lake, or any other areas which are subject to flooding or inundation by stormwater or have inadequate drainage, shall not be platted for any use as may increase danger to health, life or property. The subdivider may show, by way of accurately engineered plans, that a change to the topography in the proposed subdivision will eliminate flooding in the area in question and shall clearly demonstrate that any such planned topographical change will not unduly aggravate the flood hazard beyond the limits of the proposed subdivision. If the city planning commission determines that a flood problem does exist, then it shall reject all or that part of the proposed subdivision lying within the floodplain. Any areas of land lying within a floodplain shall require specific compliance with the subdivision act and its review by the water resources commission of the department of natural resources.

(2) Natural features. The natural features and character of lands must be preserved wherever possible and desirable. Due regard must be shown for all natural features such as large trees, stands of trees, watercourses and similar environmental assets that will add attractiveness and value to the property if preserved. Whenever such natural features are depicted as part of the city’s parks and open space system, as shown on the master plan, such features shall be either dedicated or reserved for the city as per section 106-131

(3) Artificial or manmade lakes or reservoirs. Artificial or manmade lakes or reservoirs shall comply with plans and specifications approved by the city engineer.

(4) Trees. The subdivider shall take the necessary action to preserve existing trees within the proposed subdivision. The following information shall be provided to the director of community development and the planning administrator at the time application is made for tentative approval of the preliminary plat:

a. Location of all trees to be retained within the proposed subdivision.

b. Specifications for protection during grading.

c. Specifications for grading and drainage to assure the preservation of those trees to be retained.

(5) Open space areas. Whenever a subdivider proposes to provide open space areas within a subdivision for the exclusive use of property owners within the subdivision, he shall provide the following information at the time application is made for tentative approval of the preliminary plat. This information shall be in addition to all other information required by this chapter.

a. A complete description of the land proposed to be dedicated to common ownership of lot owners, including the following as a minimum:

1. Legal description of open land.

2. Topographical survey of open land.

3. Type of soil in open land (include a minimum of one soil boring and percolation test per acre).

4. Description of natural features on open land (stands of trees or other vegetation, streams or other bodies of water, etc.).

5. Other relevant factors.

b. The proposed plan of development of the open space, which shall include the following as a minimum:

1. The proposed manner in which the title to land and facilities owned by the subdivision will be held.

2. The proposed manner of collection of maintenance costs, financing costs or assessments, so that nonpayment will constitute a lien on the property, thus avoiding city responsibility in the future.

3. The proposed manner of regulating the use of the common facilities and areas so as to eliminate possible nuisances to other property owners and cause for enforcement by the city.

4. The proposed method of notifying the city when any change is contemplated in plans that would affect the original specifications approved by the city. Any such change will require city planning commission and city council approval.

5. The proposed method of setting up assessments to cover contingencies, insurance against casualty and liability and payment of taxes relating to these properties.

6. The proposed use of open land and the proposed improvements which are to be constructed by the developer, the timetable by which they are to be constructed, and an estimate of the cost thereof prepared by a landscape architect or civil engineer licensed to practice in the state.

7. Other relevant facts related to the proposed uses of open land.

c. The provision of open space areas within a subdivision for the exclusive use of subdivision property owners shall be subject to all approvals of the planning commission and city council as outlined in this chapter.

d. If the city council gives preliminary approval to the proposed open space plan, it shall instruct the city attorney to prepare a contract setting forth the conditions upon which such approval is based, which contract, after approval thereof by the city council, shall be entered into between the city and the subdivider prior to the approval of any final plat based upon the approved preliminary plat.

e. At the time of application for final approval, the subdivider shall deposit a cash or corporate surety bond, subject to approval of the city attorney, and in the amount of the estimated cost of the proposed improvements to the open space, guaranteeing the completion of such improvements within a time to be set by the city council.

(Code 1985, § 24-18)