(A) Standards; conformance required. The specifications herein set forth are hereby declared to be the standards and general plan adopted by the City Council for the width and location of all highways, streets, and alleys which may hereafter be platted or accepted within the city, except that roads under the jurisdiction of the County Road Commission shall conform to the road and right-of-way standards and policies of the County Road Commission. All subdivision streets shall also be required to conform to the standards set forth in the transportation plan adopted by the City Planning Commission.
(B) Layout. The layout of the proposed streets shall provide for the continuation of existing streets in surrounding areas or shall conform to a plan for the neighborhood approved by the City Planning Commission in cases where topographical or other conditions preclude the continuation of existing streets. In general, those streets shall be of a width as great as that of the street so extended. Due consideration shall be given to traffic safety. Minor residential streets shall be laid out so as to discourage their use by through traffic. Due consideration shall also be given by the subdivider to the attractiveness of the street layout in order to obtain the maximum livability and amenity of the subdivision. Consideration shall also be given to the proposed use of the subdivision and proper allowance made in industrial subdivisions for potential and existing railroad right-of-way as conditions will permit. Any intersection occurring on a street which crosses a railroad track shall not be less than 400 feet from the nearest railroad right-of-way. Greater distances may be required if it is deemed necessary for safety, approach gradients, or future grade separations.
(C) Major thoroughfares. Where the subdivision abuts or contains an existing or proposed major thoroughfare, the City Planning Commission may, at its discretion, require the construction of marginal access streets, reverse frontage lots with provision of screen planting contained in a non-access reservation along the rear property lines with a minimum width of 15 feet or with side lot lines parallel to major thoroughfares, deep lots with rear-service alleys, or other treatment which the Commission considers essential to adequate protection of residential lots and to separation of through and local traffic.
(D) Private streets and alleys. Private streets and alleys shall not be permitted, but rather, all streets and alleys shall be dedicated to the public.
(E) Half-street. Half-streets shall not be permitted where a subdivision adjoins undeveloped property, except for those major streets of over 60 feet in right-of-way width as may be recommended in the city’s land use plan. They shall be permitted only when the City Planning Commission considers the use of a half-street essential to the reasonable development of the subdivision in accordance with the intent of these regulations and where the Commission finds it practicable to require the dedication of the other half of the right-of-way when the adjoining property is subdivided. Wherever there already exists a dedicated and recorded half-street or half-alley on an adjoining plat, the other half shall be dedicated on the proposed plat to make the street or alley complete.
(F) Street jogs. Street jogs with centerline offsets of not less than 150 feet should be avoided.
(G) Cul-de-sacs. Where required for the full and best utilization of the property, cul-de-sacs may be utilized. The maximum permissible length of cul-de-sacs shall be 500 feet measured from the right- of-way line of the nearest intersecting street to the farthest point on the right-of-way line of the cul-de-sac. Each cul-de-sac shall be provided at its closed end with a turnaround having a diameter at the outside of the roadway pavement of at least 80 feet and a property line diameter of at least 120 feet. The remaining portion of the cul-de-sac shall have a right-of-way width of at least 66 feet. The straight portion of the right-of-way shall be joined to the circular portion of the right-of-way by circular curves with radii not less than 50 feet.
(H) Dead-end streets. Dead-end streets shall be permitted only in cases where the City Planning Commission is of the opinion that there is a reasonable expectation that those streets will be extended to a suitable outlet when the adjacent property is platted. If the Commission permits the platting of dead- end streets with the expectation of future expansion, the Commission shall determine whether the subdivider shall provide an all weather temporary turnaround at the closed end of the street.
(I) Alleys. Alleys shall not be permitted in single-family detached or 2-family or multiple-family residential areas, but may be permitted or required in commercial or industrial areas for the purpose of service access, such as for off-street parking and loading. All such alleys shall have a minimum width of 20 feet. A diagonal cut-off shall be made at all acute and right-angle intersections of 2 alleys sufficient to provide an inside turning radius of 30 feet. Dead-end alleys shall be prohibited.
(J) Street names. Street names shall not be permitted which might cause confusion with names of existing streets in or near the city. Streets that will be continuations of existing streets shall be called by the same names of the existing streets. All names shall be approved by the City Planning Commission.
(K) Building lines and setback lines. Building lines shall conform to the requirements of Chapter 157 of this code.
(L) Right-of-way width. The minimum right-of-way width shall be 66 feet. Greater right-of-way widths for major thoroughfares and collector streets may be required by the City Planning Commission or the County Road Commission.
(M) Horizontal alignment. The centerline of the pavement shall coincide with the centerline of the right-of-way, except for irregular rights-of-way widths.
(N) Street grades. Profiles may be required on all streets at the discretion of the City Planning Commission. The minimum gradient allowed shall be not less than 0.4% and not greater than 6%, except that upon recommendation of the City Engineer an exception may be granted by the City Council.
(O) Street curvature. The minimum horizontal centerline radii of curved local streets shall be 200 feet. Greater radii may be required for principal streets having through traffic.
(P) Street alignment. When street lines deflect from each other by more than 10 degrees in alignment, the centerlines shall be connected by a curve with a minimum radius of 500 feet for major arterial streets, 300 feet for collector streets, and 150 feet for local or minor streets. Between reverse curves, on minor streets, there shall be a minimum tangent distance of 100 feet, and on collector and arterial streets, 200 feet.
(Q) Street intersections.
(1) The intersection of more than 2 streets at 1 point shall be avoided. Exceptions to this requirement shall be considered individually by the Planning Commission, and authorized only where there are no other alternatives.
(2) Streets shall intersect at 90 degrees or closely thereto, and in no case at less than 80 degrees.
(3) Except on arterials and certain collectors, T-type intersections shall be used where practical.
(4) No street intersection shall be located closer to another intersection than 200 feet.
(5) The intersections shall be provided with a minimum slope to facilitate drainage. This minimum slope shall be carried back 150 feet each way from the intersection, measured from the centerline of the intersected street. An allowance of 3% maximum intersection grade will be permitted.
(6) There shall be a clear vision zone at all corners of intersecting roads or road junctions, consisting of a triangular area defined by: the point of intersection of the right-of-way lines, and the line drawn between 2 points extended along those right-of-way lines a distance of 25 feet from the point of intersection; and within which area no obstruction to vision, excluding existing topography, shall be permitted from a height of 2 feet to 8 feet above centerline elevation of abutting streets, except that not more than 1 tree with a trunk of not more than 30 inches in diameter, and clear of any branches for those heights, may be located within that area; provided, however, that this section shall not prohibit the requirement of a greater clear vision zone where one is necessary in view of permitted traffic turning movements, existing and anticipated traffic volumes, traffic speeds, intersection configurations, geographic and topographic conditions, or any other unique characteristics which may require a greater clear vision zone. The area of the clear vision zone shall be shown as an easement on the plat.
(R) Surface drainage. The preferred plan for yard drainage shall provide for drainage from the rear of the lot to the front of the lot with a minimum grade of 1% and a maximum grade of 3% (FHA Type A).
(1) In the event it is found to be essential to the economic development of substantial portions of a project, the easement at the rear of the lot may be below the building grade. In this event, the grade shall not be less than 1% nor more than 3%, and the grade from the house to the street shall not be less than 1%, with the building grade being not less than 12 inches above the street grade. Grades in excess of 3% shall be subject to the approval of the City Engineer after recommendation from the City Planning Commission.
(2) Where low easements are essential to the economical development of major portions of the project, the longitudinal grade of that easement shall not be less than 0.4%, and the length of run of that longitudinal easement shall not exceed 500 feet of continuance drainage, with no more than 100 feet of that drainage being upstream from an angle point in the easement.
(3) Where required by the City Engineer, a 4-inch drainage tile shall be provided for easement drainage, with that drain tile being laid in a trench being backfilled with pea gravel or approved bankrun gravel. The depth of grade and outlet for the tile being subject to city approval.
(S) Access to streets across ditches. Subdividers shall provide access to all proposed streets across watercourses or ditches in a standard manner approved by the County Road Commission, the County Drain Commission, and the City Engineer, where applicable.
(T) Acceleration and deceleration lanes. Acceleration and deceleration and passing lanes shall be provided at the intersections of a minor street with a major thoroughfare as required by the highway authority having jurisdiction.
(U) Local or minor streets. These streets shall be so arranged as to discourage their use by through traffic.
(V) Relation to topography. Streets shall be arranged in proper relation to topography so as to result in usable lots, safe streets, and reasonable gradients.
(W) Marginal access streets. Where a subdivision abuts or contains a major thoroughfare, the city may require:
(1) Marginal access streets approximately parallel to and on each side of the right-of-way; or
(2) Other treatment as it deems necessary for the adequate protection of residential properties and to afford separation of through and local traffic.