§ 153.04 DESIGN STANDARDS.
   Generally, design standards shall assure that layout of the subdivision harmonizes with the existing plans affecting the development and its surroundings, and shall be in conformity with the city’s development objectives for the entire area. No plat shall be approved for any subdivision which covers an area within the floodplain unless the subdivider agrees to meet all floodplain zoning provisions and other floodplain regulations; makes improvements which will assure that each lot contains a flood free side for location of structure; designs roads so that the finished surface is not more than two feet below the regulatory flood protection elevation; and locates or designs public utilities, such as sewer, gas, electrical and water systems, to provide protection to the regulatory flood protection elevation.
   (A)   Circulation.
      (1)   General street design.
         (a)   The design of all streets shall be considered in their relation to existing and planned streets, to reasonable circulation of traffic, to topographic conditions, to runoff of storm water and to the proposed uses of the area to be served.
         (b)   Where new streets extend existing adjoining streets, their projections shall be at the same or greater width, but in no case less than the minimum required width.
         (c)   Where adjoining areas are not subdivided, the arrangement of streets in new subdivisions shall make provision for the proper projection of streets. When a new subdivision adjoins unsubdivided land susceptible to being subdivided, then the new streets shall be carried to the boundaries of the unsubdivided land.
      (2)   Street width. Arterial streets shall have rights-of-way and improved roadway widths of at least 80 and 40 feet, respectively. Similar widths for local streets shall be at least 66 and 36 feet, respectively.
      (3)   Maximum vertical grades. Maximum vertical grades shall be 4% for arterial streets and 6% for local streets.
      (4)   Cul-de-sacs. Maximum length of permanent cul-de-sac (turn around) streets shall be 500 feet measured along the center line from the intersection of origin to end of right of way. Each cul-de-sac shall be provided at the closed end with a turn around having a minimum outside roadway diameter of 100 feet, and a minimum street property line diameter of 120 feet.
      (5)   Street jogs. Street jogs with center line off-sets of less than 125 feet shall be avoided.
      (6)   Street intersections. Insofar as practical, streets shall intersect at right angles and no intersection shall be at an angle of less than 60 degrees. No intersection shall contain more than four “corners”.
      (7)   Access to arterial streets or highways. Where a proposed plat is adjacent to an arterial street or highway as designated by the Comprehensive Plan, spacing between access points to the thoroughfares of less than 660 feet for arterials and 1,320 feet for highways shall be avoided, except where impractical or impossible due to existing property divisions or topography.
      (8)   Alleys. Alleys shall be prohibited in residential areas unless special permission is granted by the Council.
      (9)   Hardship to owners of adjoining property. The street arrangements shall not be such as to cause hardship to owners of adjoining property in platting their own land and providing convenient access to it.
   (B)   Easements.
      (1)   Utilities. Easements of at least 12 feet wide centered on rear lot lines shall be provided for utilities where necessary. Easements for storm or sanitary sewers shall be at least 20 feet wide. They shall have continuity of alignment from block to block. Temporary construction easements may be required where installation depths are greater than ten feet. Utility easements shall be kept free of any vegetation which would interfere with the free movement of utility service vehicles.
      (2)   Watercourses. When a subdivision is traversed by a watercourse, drainageway, channel or stream, there shall be provided a storm water easement or drainage right-of-way conforming substantially with the lines of the watercourses, and with such further width or construction as may be determined to be necessary by the City Engineer.
   (C)   Blocks.
      (1)   Length. Block lengths shall not exceed 1,000 feet and shall not be less than 400 feet.
      (2)   Pedestrian walkways. In blocks longer than 600 feet, a pedestrian crossway with a minimum right-of-way of 20 feet shall be required near the center of the block. Additional accessways to schools, parks and other destinations shall be provided if requested by the Planning Commission at the time of preliminary plat review.
   (D)   Lots.
      (1)   Layout. Where possible, side lot lines shall be at right angles to straight street lines or radial to curved street lines. Lots with frontage on two parallel local streets shall be prohibited.
      (2)   Size and dimension. Minimum lot areas and lateral dimensions shall be as set forth in the Zoning Code.
      (3)   Corner lots. Corner lots shall be platted at least 10% wider than the minimum lot width required.
      (4)   Natural features. In the subdivision of land, due regard shall be shown for all natural features which if preserved will add attractiveness and stability to the proposed development and which may alter normal lot platting.
      (5)   Lot remnants. Lot remnants which are below the minimum lot size must be added to adjacent or surrounding lots rather than be allowed to remain as an unusable outlot or parcel unless the owner can show plans for the future use of the remnant.
(2003 Code, § 10.20)