The street layout of the subdivision shall be in general conformity with the transportation element of the comprehensive plan, and provide for the most advantageous and aesthetically pleasing development of the entire neighborhood, including adjoining areas. The general design standards set forth herein are minimum standards. Requirements in environmentally sensitive areas (soils, slope, flood hazard, woodlands and the like) may be more stringent.
(A) Street classifications. The following functional definitions of street classifications are provided.
(1) PLACE. A short street, cul-de-sac, or court. The primary purpose of a PLACE is to conduct traffic to and from dwelling units to other streets within the hierarchy of streets. Usually a place is a dead end street with no through traffic and limited on street parking.
(2) LANE. A short street, cul-de-sac, or court, or a street with branching places or lanes. The primary purpose of a LANE is to conduct traffic to and from dwelling units to other streets within the hierarchy. Occasionally a LANE will connect with two or three small places or lanes. Usually, there is no through traffic between two streets of a higher classification.
(3) SUBCOLLECTOR. Provides access to places and lanes and conducts traffic to an activity center or a higher classification street. It may be a loop street connecting one collector or arterial street at two points, or a more or less straight street conducting traffic between collector and/or arterial streets.
(4) COLLECTOR. Functions to conduct traffic between major arterial streets and/or activity centers. It is a principal traffic artery within residential areas and carries relatively high volume. A COLLECTOR has potential for sustaining minor retail or other commercial establishments along its route which will influence the traffic flow.
(5) ARTERIAL. The major street in the hierarchy. It has a high volume of traffic and is not intended to be a residential street. An arterial provides connections with major state and interstate roadways and has a high potential for the location of significant community facilities as well as retail, commercial and industrial facilities. See Figure A following:
(B) Arterial and collector streets. Arterial and collector streets shall conform to the major street plan for the city’s municipal planning area. Where such are not shown on the plan, the arrangement of streets shall provide for the continuation or appropriate projection of existing principal streets in surrounding areas.
(C) Protection of residential properties. Whenever a subdivision abuts or maintains an existing or proposed arterial street, the MPC may require service streets, double frontage lots with screen planting contained in a nonaccess reservation along the real property line, or such other treatment as may be necessary for adequate protection of residential properties and to afford separation of through and local traffic.
(D) Local streets. Local streets shall be laid out so that their use by through traffic will be discouraged.
(E) Reserve strips. Reserve strips of land controlling access to streets shall be prohibited except where their control is placed in the city, or under conditions approved by the Municipal Planning Commission (MPC).
(F) Proposed future street system. Where the plat to be submitted includes only part of the tract owned or intended for development by the subdivider, a tentative plan of a proposed future street system for the unsubdivided portion shall be prepared and submitted by the subdivider.
(G) Extending to boundary lines. Proposed streets shall be extended to the boundary lines of the tract to be subdivided, unless prevented by topography or other physical conditions, or unless such extension is not necessary or desirable for the coordination of the layout of the subdivision with the existing layout of the most advantageous future development of adjoining tracts.
(H) Intersecting of streets. Proposed streets shall intersect one another as nearly at right angles as topography and other limiting factors of good design permit. 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 MPC.
(I) Half streets. 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 Planning Commission 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.
(J) Dedication of right-of-way; cash deposit. Where a subdivision borders an existing narrow road, other than an arterial, or where there are plans to realign or widen a road that would require use of some of the land in the subdivision, the applicant shall dedicate the additional right-of-way required to widen or realign such roads. The applicant shall also be required to construct, at his or her own expense, at least a curb and one-half the pavement required by division (T) of this section. In lieu of the above, the governing body may as a minimum require the applicant to deposit in escrow an equivalent amount of cash. A greater amount may be required where it is determined that the improvement of the road provides greater benefit to the applicant.
(K) Arterial street right-of-way. Where a subdivision borders an existing or proposed arterial street, the subdivider shall be required to dedicate sufficient right-of-way to provide for its future widening. All rights-of-way proposed for dedication shall be graded and top dressed to a condition suitable for seeding prior to acceptance by the local government.
(L) Street jogs. Local street jogs of less than 125 feet should be avoided.
(M) Grade of intersections. Intersections shall be designed with a flat grade whenever practical. In hilly or rolling areas at the approach to an intersection, a leveling area should be provided having not greater than a 2% rate for a distance of 60 feet, measured from the nearest right-of-way line of the intersecting street.
(N) Curb radius. Minimum curb radius at the intersection of two local streets shall be at least 20 feet; and minimum curb radius at an intersection involving an arterial or collector street shall be at least 25 feet.
(O) Sight distance at intersections. 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 and/or vegetation in connection with grading of the public right-of-way to the extent deemed necessary to provide an adequate sight distance.
(P) Right-of-way widths. Right-of-way widths in excess of the standards designated in this chapter 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 (3:1).
(Q) Cul-de-sac streets. As a general rule, a cul-de-sac street should not exceed 500 feet in length measured from the entrance to the center of the turnaround, or have more than 17 lots facing onto it. A cul-de-sac shall be provided with a turnaround having a radius of not less than 50 feet at the property line, and not less than 42 feet at the curb line. There may be provided in the center of the turnaround an unpaved island, improved with grass and landscaping that will not interfere with sight distance, which will leave a minimum paving width of 22 feet (curb face to curb face). Where center medians are used, they shall be so designed that they will conform to the shape or form of the outside paving radius in order to promote a safe and more orderly traffic flow.
(R) Dead end streets. Dead end streets shall not be permitted except where they relate to the extension of the street in the development of adjoining land. Temporary paved T- or L-shaped turnabouts shall be constructed where lots are fronting on such temporary dead end streets, with the notation on the subdivision plat that the land outside the normal street right-of-way shall revert to abutters whenever the street is continued. Removal of the turnabout and reconditioning of the right-of-way shall be at the expense of the subdivider developing the adjoining tract. The length of temporary dead end streets should not exceed 1,000 feet in length.
(S) Minimum right-of-way widths. Street right-of-way widths shall be in accordance with the major street plan and where not designated therein, shall not be less than the following:
Alleys | 20 feet |
Collector | 60 feet |
Lanes and places | 50 feet |
Major arterial or highway | 120 feet |
Minor arterial | 80 feet |
Subcollector | 50 feet |
(T) Pavement widths. The minimum street pavement widths measured from curb face to curb face shall be as follows:
Alleys and service drives | 18 feet |
Collector | 32 feet |
Lanes and places | 26 feet |
Minor arterial | 44 feet |
Subcollector | 26 feet |
(U) Grades. The grades of all streets shall not exceed the following:
Lanes and places | 10% |
Minor arterial and collector | 6% |
Subcollector | 10% |
No street grade shall be less than 0.5% | |
(V) Alignments. The horizontal and vertical alignment for all streets shall not be less than the following:
(1) (a) Horizontal alignment - centerline radius.
Collectors, subcollectors | 100 feet minimum |
Minor arterials | 300 feet minimum |
Places, lanes | 50 feet minimum |
(b) There should be a tangent between all reverse curves having an adequate length, in relation to the radii of the curves, to provide for a smooth flow of traffic.
(2) All changes in street grades shall be made with vertical curves with not less than the following minimum lengths:
Collector, local | 100 feet, but not less than 20 feet for each algebraic difference of the intersecting slope lines* |
Minor arterials | 200 feet, but not less than 50 feet for each algebraic difference of the intersecting slope lines |
*This requirement may be waived where the algebraic difference is less than 0.60% | |
(Prior Code, § 11-6-1) (Ord. 594, passed 8-5-1997)