(A) Layout. The preliminary plat shall show proposed street layout and width. The layout shall include all contiguous land owned by the subdivide.
(B) Design.
(1) Street layout shall be consistent with the comprehensive plan and provide for public safety, efficient traffic circulation and stormwater runoff.
(2) If a proposed subdivision abuts unsubdivided land, the street layout shall allow for appropriate street continuation into adjoining areas. The streets shall be carried to the boundaries of the unsubdivided land.
(C) Width and grade.
(1) (a) The right-of-way width of all streets shall conform to the following minimum dimensions:
1. Arterials, 80 feet;
2. Collector streets, 66 feet;
3. Local streets, 60 feet;
4. Frontage roads, 50 feet; and
5. Cul-de-sac radius, 60 feet.
(b) Greater or lesser widths may be required depending upon anticipated traffic volumes, planned function of the street and character of planned abutting land uses. The Director of Engineering and Zoning Administrator shall specify the width(s) in the staff report to the Planning Commission and City Council.
(2) (a) All center line gradients shall be at least 0.5% and shall not exceed the following:
1. Arterials and thoroughfares, 5%;
2. Collector streets, 6%; and
3. Minor streets, 8%.
(b) The Director of Engineering may consider, on arterials and collector streets, a maximum of 8% grade where existing topography dictates.
(D) Minimum carrying capacity.
(1) Seven-ton axle loading for local streets; and
(2) Nine-ton axle loading based on traffic volume for arterial and collector streets.
(E) Maximum levels of service (LOS). The impact of increased subdivision build-out density on traffic volumes shall be consistent with the maximum acceptable design LOS indicated in the comprehensive plan for existing or planned arterials, collector streets, and frontage roads. Increased density and traffic volumes shall be concurrent with planned LOS capacity and availability.
(F) Intersections. Insofar as practical, streets shall intersect at right angles. In no case shall the angle formed by the intersection of two streets be less than 60 degrees. Intersections having more than four corners shall be prohibited. Adequate land for future intersection and interchange construction needs shall be dedicated to the city.
(G) Tangents. A tangent of at least 100 feet shall be introduced between reverse curves on collector streets and 50 feet on lesser streets.
(H) Deflections. Other than at intersections, connecting street lines that deflect from each other shall be connected by a curve with a radius adequate to ensure a sight distance of no less than 500 feet for arterials, 300 feet for collectors, 100 feet for all other streets.
(I) Intersection offsets. Centerlines of arterial and collector streets at intersections shall not be offset. Offsets of focal streets shall be considered on a case by case basis by the Director of Engineering.
(J) Local streets. Local streets shall be laid out so as not to encourage through traffic.
(K) Cul-de-sacs. The undesirable effects of cul-de-sacs on traffic movement, emergency vehicle access, school bus traffic and snowplowing require limiting the maximum length of a street terminating in a cul-de-sac to 500 feet, measured from the centerline of the street of origin to the end of the right-of-way.
(L) Access to arterial streets. If a proposed plat abuts a limited access highway or arterial street, there shall be no direct vehicular or pedestrian access from individual lots to the highways or streets. Access to arterials shall be at intervals of not less than ¼-mile and through existing and established crossroads. The City Council may require the developer to provide local service drives along the right-of-way of arterials, or the Council may require that lots back on the arterial, in which case, vehicular and pedestrian access between the lots and arterial shall be prohibited.
(M) Platting of small tracts fronting arterial streets. In the platting of small tracts of land fronting arterial streets, where there is no convenient access to existing entrances, and where access from the plat would be closer than ¼-mile from an existing access point, an entrance permit may be granted. Provision shall be made in the plats for the connection of roads to abutting land. As the abutting land is developed, and access becomes possible at a preferred location, the City Council may, upon public hearing, revoke the entrance permit.
(N) Stub streets. Where adjoining lands are not subdivided, some of the streets in the new subdivision shall be required to extend to the boundary line of the tract to provide for future access.
(O) Street continuation and extension. Street layout shall provide for the continuation of existing streets from adjoining areas into the new subdivision when such extension is shown on the comprehensive plan, or whenever the extension would meet traffic circulation objectives as determined by the City Council.
(P) Half streets. Half streets shall be prohibited.
(Q) Private streets. Private streets may be permitted only in planned unit developments (PUDs), however, they must conform to the same standards as public streets.
(R) Corners. Curb lines at street intersections shall be rounded at a radius of not less than 20 feet. Corners at the entrances to the turnaround portion of cul-de-sacs shall have right-of-way radii of not less than 35 feet.
(S) Alleys. Alleys, where permitted by the city, shall be at least 20 feet wide in residential areas and at least 24 feet wide in commercial areas. The city may require alleys in commercial areas where adequate off-street loading space is not available. Dead-end alleys, alley intersections and sharp changes in alignment shall be prohibited.
(T) 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.
(`86 Code, § 10.35) (Am. Ord. 706, passed 12-2-97)