The following design standards shall apply to the design of streets:
1. General. In order to provide for streets of suitable location, width, and improvement to accommodate prospective traffic and afford satisfactory access to police, fire fighting, snow removal, sanitation, and street maintenance equipment, and to coordinate streets so as to compose a convenient system and avoid undue hardships to adjoining properties, the following design standards for streets are hereby required:
A. A tangent of at least 100 feet long shall be introduced between reverse curves on municipal arterial and municipal collector streets, and 75 feet on municipal service streets.
B. When connecting street lines deflect from each other at any one point by more than 10 degrees, they shall be connected by a curve with a radius adequate to insure a sight distance of not less than 100 feet for municipal service and municipal collector streets, and of such greater radii as the Council shall determine for special cases.
C. Minimum Roadway and Right-of-way Standards:
(1) Municipal arterial streets shall have a right-of-way width of not less than 80 feet and a roadway width of not less than 44 feet.
(2) Municipal collector streets shall have a right-of-way width of not less than 60 feet and a roadway width of not less than 36 feet.
(3) Municipal service streets shall have a right-of-way width of not less than 50 feet and a roadway width of not less than 26 feet.
(4) Frontage streets shall have a right-of-way width of not less than 40 feet and a roadway width of not less than 26 feet.
(5) Culs-de-sac shall meet all the requirements for a municipal service street and, in addition, shall provide a turnaround with a right-of-way radius of 50 feet and a roadway radius of 40 feet. No cul-de-sac shall exceed 500 feet in length.
D. Street grades, wherever feasible, shall not exceed the following:
(1) Municipal arterial streets - six percent.
(2) Municipal collector streets - eight percent.
(3) Municipal service streets - 10 percent.
(4) Frontage streets - six percent.
E. All changes in street grade shall be connected by vertical curves of minimum length in feet equal to 20 times the algebraic difference in percent of grade.
F. No street grade shall be less than one-half of one percent.
2. Street Surfacing and Improvements. After sewer, water, and other utilities to be located underground within the right-of-way have been installed by the applicant, the applicant shall construct curbs and gutters and shall surface or cause to be surfaced roadways to the widths prescribed in these regulations. Said surfacing shall be of Portland concrete cement. Adequate provisions shall be made for culverts, drains, and bridges. All road pavement, shoulders, drainage improvements and structure, curbs, turnarounds, and sidewalks shall conform to all construction standards and specifications adopted by the City, and shall be incorporated into the construction plans required to be submitted by the developer for plat approval.
3. Excess Right-of-way. Right-of-way widths in excess of the standards designated in these regulations shall be required whenever, due to topography, additional width is necessary to provide adequate earth slopes. Such slopes shall not be in excess of three to one.
4. Railroads and Limited Access Highways. Railroad rights-of-way and limited access highways which were so located as to affect the subdivision of adjoining lands shall be treated as follows:
A. In residential districts, a buffer strip at least 25 feet in depth in addition to the normal depth of the lot required in the district shall be provided adjacent to the railroad right-of-way or limited access highway. This strip shall be part of the platted lots and shall be designated on the plat: “This strip is reserved for screening. The placement of structures hereon is prohibited.”
B. In districts zoned for business, commercial, or industrial uses, the nearest street extending parallel or approximately parallel to the railroad shall, wherever practicable, be at a sufficient distance therefrom to ensure suitable depth for commercial or industrial sites.
C. Streets parallel to the railroad when intersecting a street which crosses the railroad at grade shall, to the extent practicable, be at a distance of at least 150 feet from the railroad right-of-way. Such distance shall be determined with due consideration of the minimum distance required for future separation of grades by means of appropriate approach gradients.
5. Intersections. The following standards shall apply to the design of intersections:
A. Streets shall be laid out so as to intersect as nearly as possible at right angles. A proposed intersection of two new streets at an angle of less than 75 degrees shall not be acceptable. An oblique street should be curved approaching an intersection and should be approximately at right angles for at least 100 feet therefrom. Not more than two streets shall intersect at any one point unless specifically approved by the Council.
B. Proposed new intersections along one side of an existing street shall, wherever practicable, coincide with any existing intersections on the opposite side of such street. Street jogs with centerline offsets of less than 150 feet shall not be permitted, except where the intersected street has separated dual drives without median breaks at either intersection. Where streets intersect major streets, their alignment shall be continuous. Intersection of major streets shall be at least 800 feet apart.
C. Minimum curb radius at the intersection of two municipal service streets shall be at least 20 feet; and minimum curb radius at an intersection involving a municipal collector street shall be at least 25 feet. Abrupt changes in alignment within a block shall have the corners cut off in accordance with standard engineering practice to permit safe vehicular movement.
D. Intersections shall be designed with a flat grade wherever practical. In hilly or rolling areas, at the approach to an intersection, a leveling area shall be provided having not greater than a two percent rate at a distance of 60 feet, measured from the nearest right-of-way line of the intersecting street.
E. Where any street intersection will involve earth banks or existing vegetation inside any lot corner that would create a traffic hazard by limiting visibility, the developer shall cut such ground or vegetation, including trees, in connection with the grading of the public right-of-way to the extent deemed necessary to provide an adequate sight distance.
F. The cross-slopes on all streets, including intersections, shall be three percent or less.
6. Bridges. Bridges of primary benefit to the applicant, as determined by the Council, shall be constructed at the full expense of the applicant without reimbursement from the City. The sharing expense for the construction of bridges not of primary benefit to the applicant, as determined by the Council, will be fixed by special agreement between the Council and the applicant. Said cost shall be charged to the applicant pro rata as the percentage of his or her land developed and so served.
7. Alleys. The following design standards for alleys shall be required of all subdividers:
A. Alleys shall be prohibited in residential districts.
B. Alleys shall be provided in commercial and industrial districts, except that the Council may waive this requirement where other definite and assured provision is made for service access, such as off-street loading, unloading and parking consistent with and adequate for the uses proposed.
C. Alleys shall have a right-of-way of not less than 30 feet and a roadway width of not less than 20 feet.
D. Alley intersections and sharp changes in alignment shall be avoided, but where necessary, corners shall be cut off sufficiently to permit safe vehicular movement.
E. Dead-end alleys shall be avoided where possible, but if unavoidable, shall be provided with adequate turnaround facilities at the dead end, as determined by the Council.
8. Street Dedications and Reservations. The following provisions shall apply to street dedications and reservations:
A. Street systems in new subdivisions shall be laid out so as to eliminate or avoid new perimeter half streets. Where an existing half street is adjacent to a new subdivision, the other half of the street shall be improved and dedicated by the subdivider. The Council may authorize a new perimeter street where the subdivider improves and dedicates the entire required street right-of-way width within his or her own subdivision boundaries.
B. Where a subdivision borders an existing narrow street or when City plans or zoning setback regulations indicate plans for realignment or widening a road that would require use of some of the land in the subdivision, the applicant shall be required to improve and dedicate at his expense such areas for widening or realignment of such roads. Such frontage roads and streets shall be improved and dedicated by the applicant at his or her own expense to the full width as required by these subdivision regulations. Land reserved for any street purposes may not be counted in satisfying yard or area requirements of the zoning regulations whether the land is to be dedicated to the City in fee simple or an easement is granted to the City.