All streets in the Town, unless otherwise specified in these Subdivision Regulations, shall be designed to the standards in this subsection and as follows:
A. Minimum required Right-of-Way widths shall be provided as set forth in Table 5-1 below. Additionally, the following standards shall apply:
1. Cul-de-sac streets shall terminate in a circular right-of-way sixty (60) feet in radius with a minimum improved traffic turning circle forty-eight (48) feet in radius.
2. Dead end streets will not be approved except in locations designated by the Zoning Administrator or his/her designee as necessary for future extension to facilitate development of adjacent lands. A dead end street serving more than four (4) lots shall provide a temporary turning circle with a forty-eight (48) foot radius or other acceptable design to accomplish adequate access.
3. Local roads for commercial or industrial subdivisions are highly recommended at sixty (60) feet. However, when the size of subdivisions or other factors limit the inclusion of the sixty (60)-foot rights-of-way, the Zoning Administrator or his/her designee may approve the use of fifty (50)-foot rights-of-way with all intersection chamfers at forty-five (45) feet.
4. Access or frontage streets shall be provided as required by a traffic impact study.
Table 5-1 Town Public Street Minimum Design Standards | |||||||
Item | Principal Arterial (1) |
Urban Arterial | Rural Arterial | Urban Collector | Urban Local Road SR-0.16, MR | Rural Local Road SR-1, SR-1.6, SR-2, SR-2.5, AR-4, AR-5, AR-36 | Commerci al & Industrial |
Minimum Right-of-way | Per ADOT(1) | 80' | 80' | 80' | 50'(4) | 50' | 60' |
Minimum Roadway Width w/o On Street Parking | Per ADOT | 51' | 24' | 28' | 24' | 20' - 24' | 28' |
Pavement Edge Treatment | 7" ADOT C&G | 6" Vert. C&G | 4' - 6' shoulder, each side, thickened edge | Vertical Curb | Rolled Curb | 4' - 6' shoulder each side, thickened edge | 6" Vert. C&G |
Sidewalk | 6' on each side | 5' Min. on each side(2) | None(3) | 5' Min. on one side(3) | 5' Min. on one side(3) | None(3) | 5' detached 6' Min. on each side(2) |
Street Design Notes (1) Currently, all principal arterial routes are state highways, owned and maintained by the Arizona Department of Transportation. (2) Sidewalk may be required on only one (1) side of the road with an increased width if approved by the Zoning Administrator or his/her designee and the Public Works Director. (Also, see note #3.) (3) A minimum of two (2) foot wide shoulders is required if no sidewalk is installed. These shoulders shall maintain the same slope as the pavement and shall be constructed of ABC or an approved equal. However, construction of sidewalks on collector roads shall be determined through a Development Agreement. Note: These standards are primarily for new roadway construction. These standards may be adjusted on projects involving rehabilitation or reconstruction of existing improvements as approved by the Public Works Director. (4) 62' versus 50-feet right-of-way options for urban level local street to accommodate subdivision that have on-street parking versus no on-street parking. | |||||||
Table 5-2 Rural Subdivision Private Street Minimum Design Standards(1) (2) | |||||||
Number of Lots(3) | Right-of-way Width | Subgrade | Base Depth | Surface Depth | Edge Improvements | Accept ROW? | |
Total Width
| Improvement Width
| ||||||
2 to 3 | 50 | 20 | 6" | 4" | 2" Dust free material | None | No |
4 to 10 | 50 | 24 | 6" | 6" | Double Chip | Ribbon/ Thickened Edge | No |
More than 10 | 50 | 24 | 6" | 6" | 3" Asphalt | Ribbon/ Thickened Edge | Council Discretion |
(1) Rural subdivision private streets shall meet the roadway geometric criteria and pavement structural section requirements set forth in Sections 5.3.2(A) - (D) of these Subdivision Regulations. (2) Subdividers utilizing rural subdivision private streets shall be required to meet the homeowners’ association requirements set forth in Section 5.3.2(E) of these Subdivision Regulations. (3) If the proposed subdivision serves as an access point to other lots or parcels, and the total number of potential remaining lots that could be developed, together with the proposed subdivision, is more than 10, the proposed subdivision shall make the “Improvement Width” the same as a development with 10 or more lots. As an example, if the proposed subdivision is three lots, but the private street could continue beyond the proposed subdivision to include more than 10 lots, the “Improvement Width” must be 24 feet. Surface Depth and Edge Improvements shall remain as listed for the proposed number of lots in the proposed subdivision. | |||||||
B. Grades
1. Maximum:
a. Arterial routes: as determined by the Public Works Director.
b. Collector streets eight (8) percent.
c. Local residential streets twelve (12) percent.
(Maximum longitudinal slopes of up to eighteen (18) percent may be used for a distance not to exceed three hundred (300) feet if existing terrain dictates, and if approved by the Public Works Director).
d. Cul-de-sacs eight (8) percent.
e. Intersections five (5) percent for a minimum of fifty (50) feet from points of intersection.
2. Minimum: all streets shall have a minimum longitudinal slope of four-tenths (0.4) percent.
3. Desirable: all streets six (6) percent.
4. Exceptions may be made upon showing of extraordinary circumstances by the subdivider and review and approval by the Public Works Director.
C. Vertical Curves
1. Arterial routes: Minimum length, one hundred (100) feet, or as determined by using the AASHTO Standards.
2. Collector and minor streets: Minimum length, one hundred (100) feet, or as determined by using the AASHTO Standards for residential streets, the length of the vertical curve may be reduced to fifty (50) feet if existing terrain dictates and if approved by the Public Works Director.
3. When the longitudinal grade for all streets changes with an algebraic difference of one (1) percent as measured between the tangent grades in percent, a vertical curve shall be provided.
D. Horizontal Alignment
1. Arterial routes: As determined by the Public Works Director.
2. When tangent center lines deflect from each other more than ten (10) degrees and less than ninety (90) degrees, they shall be connected by a curve with a minimum centerline radius of five hundred (500) feet for collector streets and one hundred fifty (150) feet for local streets.
3. Between reverse curves there shall be a tangent section of centerline not less than one hundred (100) feet long, unless the radius exceeds seven hundred fifty (750) feet on arterial and collector streets or two hundred fifty (250) feet on local streets, in which cases fifty (50) feet of tangent shall be required if approved by the Public Works Director.
4. Intersecting arterial and collector streets shall do so at an angle that shall not vary from ninety (90) degrees by more than ten (10) degrees; intersections of local streets shall not vary from ninety (90) degrees by more than fifteen (15) degrees.
5. Street jogs shall be avoided. Street intersections shall be a minimum of one hundred-fifty (150) feet apart unless otherwise approved by the Public Works Director.
6. Minor streets intersecting a collector street or arterial route shall have a tangent section of centerline at least one hundred fifty (150) feet in length measured from the right-of-way line of the major street; except that, no such tangent is required when the minor street curve has a centerline radius greater than four hundred (400) feet with the center located on the major street right-of-way line.
Where topographic conditions make necessary other treatment to secure the best overall design, these standards may be modified by the Public Works Director.
7. Street intersections with more than four (4) legs, and Y-type intersections where legs meet at acute angles shall be avoided.
8. At street intersections, property line corners shall be rounded by circular arc having a minimum chamfer length of thirty-five (35) feet for collector and arterial streets and twenty-five (25) feet for local streets.
E. Private Streets
1. Private streets in zoning districts that do not permit rural subdivisions shall be constructed to conform to current Town street standards, including but not limited to right-of-way widths, roadway geometric criteria, and pavement structural section. Private streets in zoning districts that allow rural subdivisions shall be constructed to conform to current Town street standards, including but not limited to right-of-way widths, roadway geometric criteria, and pavement structural section, except as specifically modified by Table 5-1 above.
2. If private streets are proposed for a subdivision, whether urban or rural, maintenance of such streets shall be solely the responsibility of the homeowners. A homeowners’ association shall be established at the time the final plat is approved with a mechanism for collecting funds to be placed in an escrow account for future maintenance of the private streets. A note shall be placed on the final plat that states, “All private streets shown on this plat shall be maintained by the homeowners association. The Town will not maintain these streets and will not take the streets into the public street system unless they are improved, at the sole expense of the property owners, to the Town public street standards that are in effect at the time of the request.”
3. An emergency rapid entry system for unrestricted entry of police and fire emergency vehicle at all gated locations shall be provided. For uniformity, the only allowable system shall be the “Knox Rapid Entry System.”
(Ord. 2020-885, passed 9-8-2020)