Chapter 17.20
STREET PLANNING
Sections:
17.20.010 General layout criteria.
17.20.020 Intersection criteria.
17.20.030 Arterial street criteria.
17.20.040 Collector street criteria.
17.20.050 Local street criteria.
17.20.060 Cul-de-sac turn-around criteria.
17.20.010 General layout criteria.
A. Whenever the subdivision embraces any part of a street designated in the adopted general development plan or any adopted neighborhood or specific plan, such street shall be platted in conformity therewith; provided, however, that the developer may request, and the public works department and the commission may recommend and the council may approve minor deviations in alignment whenever it is found to be impractical to conform to the exact alignment shown on the general development plan or other plan because of adverse topography, drainage problems, existing development or traffic safety. Such minor deviations may be made without adversely affecting the public purpose to be served by the street; provided, however, that the distance between an arterial or collector and a parallel arterial or collector does not exceed 1,320 feet.
B. Street layouts shall provide for the continuation of existing and proposed arterial and collector streets into adjacent areas and such other streets as the commission may designate. Streets which the commission should designate include, but are not limited to, collector and local streets, are required to provide future connection with adjoining unplatted lands. In general, these extensions should not be farther apart than the 1,320-foot maximum permitted block length.
C. Half streets shall be discouraged except when necessary to provide right-of-way required by the general development plan to complete a street pattern already begun or to ensure reasonable development of the adjoining unplatted parcel. Where a half street exists abutting a tract, the remaining half street shall be platted within the tract. Where a half street furnishes the sole access to a lot, the subdivider shall plat and develop a street of sufficient width to accommodate two-way traffic. Dead-end streets shall not be approved except where specifically designated by the commission as necessary for connection to adjacent unplatted lands. In any case a dead-end street serving more than four lots shall provide by easement a temporary cul-de-sac turnaround conforming to the provisions herein. Dead-end alleys shall be prohibited.
D. Street access to a subdivision shall be provided as required by the commission. In general, the subdivision shall have at least two street accesses serving each forty acres or smaller tract, unless the subdivider can show to the satisfaction of the commission that the number of lots in the subdivision makes this requirement an unjustified burden. Where access must be provided across land not owned by the subdivider, the subdivider shall provide at least 60 feet of right-of-way.
E. All streets, alleys, sidewalks, paving, curbs, driveways and drainage shall be installed by the subdivider and shall meet the minimum standards and requirements of the Federal Housing Administration and the standards in Section 15.05.050, as the same may be amended.
F. When a residential subdivision abuts the right-of-way of a commercial or industrial land use, the commission may recommend location of a street approximately parallel to such right-of-way or use at a distance suitable for appropriate use of the intervening land, such distance being determined with due regard for approach ways, drainage, bridges or future grade separations.
G. Crosswalks are not considered a satisfactory substitute for a directional street layout and shall generally be avoided; however, where essential for circulation and access to schools, playgrounds and other community facilities, crosswalks 16 feet wide may be required by the commission. Such walks may be used for utility installations.
H. Unless otherwise noted, all width measurements are to property lines and all length measurements are along the centerline of the right-of-way and to the centerline of intersecting streets. (Ord. 06-07 § 1, 2006; prior code § 13-1-7(A))
17.20.020 Intersection criteria.
A. Streets intersecting an arterial or collector street shall do so at a 90-degree angle. Local streets shall typically intersect at right angles but in no case less than 75 degrees.
B. Local streets intersecting a collector street or arterial street shall have a tangent section of centerline at least 150 feet in length measured from the right-of-way line of the major street, except that no such tangent is required when the local street curb has a centerline radius greater than 400 feet.
C. Street jogs with centerline offsets less than 125 feet shall be avoided except where waived by the commission based on the recommendation of the town clerk.
D. Street intersections with more than four legs and Y-type intersections with legs, meeting in acute angles, shall be avoided. (Ord. 06-07 § 1, 2006; prior code § 13-1-7(B))
17.20.030 Arterial street criteria.
A. Arterials are designed for maximum utilization by through traffic and minimal access from adjacent property. Major arterials are intended to carry high-volume, high-speed traffic with restricted access to property and minimal intersecting traffic. Access directly onto an arterial from residential property shall be prohibited by the construction of a frontage street or a one-foot no-access easement with a vertical curb. Access directly onto a major arterial from any commercial or industrial property shall be prohibited by the construction of a frontage street. Access to a major arterial shall be restricted to one access every 660 feet. Arterials are located at approximately one-mile intervals as designated on the general development plan. The requirement for a frontage street or the prohibition of access to an arterial street may be waived by the council upon request of the subdivider and recommendation by the commission providing the subdivider can show that existing development prohibits the reasonable development of an adequate frontage street and that the proposed alternate plan for access will preserve the traffic function of the arterial street and protect residential properties from the nuisance and hazard of high-volume noisy traffic.
B. Right-of-way for major arterials shall be 110 feet. Right-of-way for minor arterials shall be 80 feet. Corners shall be rounded with a 25-foot-radius curve.
C. Horizontal curves shall have a 600-foot minimum radius.
D. The length of tangent between reversed curves shall be 100 feet. (Ord. 06-07 § 1, 2006; prior code § 13-1-7(C))
17.20.040 Collector street criteria.
A. Collectors are designed for utilization by through traffic and limited direct access from adjacent property. Access directly onto a major collector from residential property shall be discouraged. Major collectors are located at approximately one-half-mile intervals as designated on the general development plan. Minor collectors are located at approximately one-quarter-mile intervals. In commercial areas, all collector streets shall be designed and constructed to the standards established for major collectors.
B. Right-of-way for major collectors shall be 80 feet. Right-of-way for minor collectors shall be 60 feet. Corners shall be rounded with a 20-foot-radius curve.
C. Horizontal curves shall have 400-foot radius.
D. Length of tangent between reverse curves shall be 100 feet. (Ord. 06-07 § 1, 2006; prior code § 13-1-7(D))
17.20.050 Local street criteria.
A. Local streets are designed to discourage their use by through traffic and to provide access to adjacent property. Local streets in commercial areas shall be designed to conform to the criteria for minor collector streets. Major local streets shall generally be provided; however, minor local streets may be used where the street serves 28 dwelling units or fewer.
B. Right-of-way for major local streets shall be 60 feet. Right-of-way for minor local streets shall be 50 feet. Corners shall be rounded with a 10-foot-radius curve.
C. Horizontal curves shall have a 200-foot minimum radius where tangent centerlines deflect from each other more than 10 degrees and less than 75 degrees. Horizontal curves shall have a 50-foot minimum radius where deflection between tangents is 75 degrees or larger.
D. Length of tangent between reversed curves shall be 100 feet. (Ord. 06-07 § 1, 2006; prior code § 13-1-7(E))
17.20.060 Cul-de-sac turn-around criteria.
A. Unless otherwise authorized or approved by the mayor and council, cul-de-sac turn-arounds may be used at the end of minor local-type streets providing the length of the minor local street does not exceed 660 feet.
B. Right-of-way for a cul-de-sac in a residential area shall be a 100-foot-diameter circle. Right-of-way for a cul-de-sac in a commercial area shall be a 130-foot-diameter circle. Corners shall be rounded with a 25-foot-radius curve. (Ord. 06-07 § 1, 2006; prior code § 13-1-7(F))
17.20.070 Alley criteria.
A. Alleys may be developed at the option of the subdivider. When alleys are platted, the alley alignment and arrangement shall provide optimum convenience for truck service circulation and to avoid alley openings opposite fronts of residential lots. Alleys shall be required at the rear of multiple family residential, commercial or industrial developments except where, in the opinion of the commission, other provision is made for adequate permanent access for purposes of fire protection, parking and loading.
B. Right-of-way for alleys shall be 20 feet. Corners shall be cut off to form a 10-foot-by-10-foot triangle.
C. Horizontal curves shall have a 40-foot minimum radius. (Ord. 06-07 § 1, 2006; prior code § 13-1-7(G))