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All subdivisions, except minor subdivisions as defined in Section 11-012-05, Other Terms Defined, shall comply with the following standards:
1. General: The PZC and Council shall give full consideration and weight to the following:
A. Street intersections in residential areas may be of a "T" rather than an "X" design wherever such design will not unduly restrict a free movement of traffic.
B. Reserve strips controlling access to public streets shall be permitted provided that the control and disposition of land comprising such strip is placed within the jurisdiction of the city under conditions specified by the Council and shown on the plat.
2. Block Numbers: Block numbers shall be designated as required by Idaho Code.
3. Lot Layout:
A. Dimensions: Lot area, dimensions, and minimum street frontage shall be as established in Chapter 11-07, Development and Design Standards, and as otherwise provided in this Code. An alley does not qualify as required street frontage. The front lot line may directly abut a collector or arterial street provided that a public, rear-loaded access is provided at the rear of such lots to provide direct lot access. Direct lot access to the collector or arterial is prohibited.
B. Building Envelope: To guide compatible building siting, the Director may require a building envelope that identifies the setbacks shown on the preliminary plat or site plan.
C. Double Frontage Lots: Double frontage lots are prohibited except where it is shown that unusual topography or other conditions make it impossible to meet this requirement. Lots with double frontage shall be limited to one street access on one frontage by a plat note.
D. Landlocked Parcels: All parcels that do not have required frontage shall be labeled "non-buildable" on the plat. Each such non-buildable lot shall be required to have a pedestrian ingress and egress easement provided to it unless street frontage exists that adequate for a pedestrian pathway.
4. Public Streets: The arrangement, character, extent, width, grade, and location of all streets shall conform to the standards of the City of Boise, ACHD, and Idaho Transportation Department as applicable, and shall be considered in their relation to existing and planned streets, topographic conditions, to public convenience and safety, and in their appropriate relation to the proposed uses of the land served.
A. Street Design: The design of all public streets shall conform to requirements as established by the ACHD.
B. Street Grades: Street grades shall be such as to provide for the safe movement of traffic in all weather and for adequate drainage of both streets and abutting properties.
C. Partial Street Dedications: Partial street dedications shall not be permitted unless the street forms the boundary of the property being subdivided, the adjacent property is not under common ownership, and the street is anticipated to be a through street upon development of adjacent properties. All partial street dedications shall require construction of partial street sections that meet ACHD standards.
D. Dead-End Streets: Dead-end streets shall not be permitted, except that streets terminating at the boundary of a subdivision may be allowed when the street is shown on the Boise City Comprehensive Plan or when, the ACHD or Council, agrees that the extension of the street is necessary to the proper development of the street pattern. A sign indicating that the street is planned to be extended in the future will be installed at the end of the street.
E. Street Names: Proposed streets that are a continuation of an existing street shall be given the same name as the existing street. All street names used shall not duplicate or be of a spelling or pronunciation apt to be confused with the names of existing streets within the Ada County area. The applicant shall obtain approvals for all street names within the proposed subdivision from the Ada County Street Name Committee prior to submitting the plat for signature by the City Engineer.
F. Sidewalks: Sidewalks shall be required on both sides of the street. Sidewalks shall be a minimum of five feet wide when adjacent to curbs and a minimum of four feet wide when separated from the curb by a landscaped area.
G. Street Patterns:
(1) Street Network: Street patterns in residential neighborhoods shall be designed to create a network of streets that allow local trips to circulate in the area without encouraging through traffic between arterial streets. Such a pattern shall benefit the collector and arterial network by keeping local trips on local roads and provide emergency vehicles with multiple routes to access any parcel.
(2) Multi-Modal Street Patterns: Street patterns in residential neighborhoods shall be designed for the needs of the bicyclist, pedestrian, and motor vehicle alike.
(a) The circulation plan for a subdivision shall incorporate and tie into existing or proposed pathways and take into account topography, parcel lines, or other features.
(b) Streets should be designed to convey residents conveniently to parks, schools, and shopping areas in the neighborhood; and to adjacent neighborhoods. A multi-use subdivision should be designed to provide roadway connections between the various uses.
(c) A free flow of pedestrian and vehicular traffic through local neighborhoods is encouraged. Pedestrian traffic shall be accommodated on local roads, or on pathways, in cases where the roadway network is inadequate for this purpose. Connectivity with adjacent parcels and subdivisions shall be included where ever possible. Except for designated connector and arterial streets, connectivity shall be designed to discourage cut-through traffic while allowing flow of local traffic without accessing the connector-arterial network.
(d) Local streets shall provide for non-motorized travel and shall be designed to encourage slow auto speeds. Traffic calming strategies, such as reduced rights-of-way, chokers, traffic circles, and chicanes (as described in the ACHD Traffic Calming Policy) should be employed. Traffic calming devices that can significantly impede the response of or possibly damage emergency vehicles, such as speed-bumps are not allowed.
(e) Roads shall be designed to accommodate bike routes or lanes.
5. Private Streets:
A. Required Findings: Private streets shall:
(1) Provide safe and effective movement of vehicular and pedestrian traffic;
(2) Not adversely affect access or good public transportation planning to adjacent property and the area network;
(3) Not landlock adjacent property;
(4) Not restrict public access to places of public interest;
(5) Not connect one public street to another; and
(6) Not interfere with the continuity of public streets.
B. Requirements:
(1) Comply with the ACHD structural standards for streets. The design shall be prepared and certified by a registered professional engineer.
(2) The plat shall contain the following:
(a) A legal description,
(b) Identification of a recorded ingress-egress easement agreement,
(c) Conveyance to each lot owner the perpetual right of ingress and egress over the described private drive, and
(d) Provision that such perpetual easement shall run with the land.
(e) Certification of construction to ACHD specifications is required, with the exception of ACHD street width requirements.
C. Use Specific Standards:
(1) Single Family/Townhouse/Duplex Residential:
(a) Private streets may be permitted when:
i. The parcel shape or site topography will not allow street design to meet ACHD width standards; or
ii. In the cases in which conformance to ACHD requirements is in conflict with the intent of minimizing disruption to vegetation as defined in the Hillside and Foothill Areas Development Ordinance.
(b) Standards For Single Family/Townhouse/Duplex Residential:
i. Single Family/Townhouse/Two Family Private Residential Street Standards shall be according to Table 11-09.1, Private Residential Street Standards: Single-family/Townhouse/Duplex:
Number of Residential Lots vs. Street Length | Minimum R/W Width (feet) | Street Width Back of Curb to Back of Curb (feet) | Sidewalk Required Both Sides | Sidewalk Required One Side | Sidewalk Easement Allowed |
Number of Residential Lots vs. Street Length | Minimum R/W Width (feet) | Street Width Back of Curb to Back of Curb (feet) | Sidewalk Required Both Sides | Sidewalk Required One Side | Sidewalk Easement Allowed |
Up to 3 lots w/length less than 200 feet | 24 | 24 | No | Yes | Yes* |
Up to 3 lots w/length greater than 200 feet | 28 (24 for the final 200 feet) | 28/24 | No | Yes | Yes* |
4 to 10 lots w/length less than 200 feet | 24 | 24 | Yes | No | Yes* |
4 to 10 lots w/length greater than 200 feet | 28 (24 for the final 200 feet) | 28/24 | Yes | No | No |
11 or more lots | 40 | 28 | Yes | No | No |
* Setback requirements shall be from the back of sidewalk where sidewalks are placed within an easement and not separated from the street by landscaping. If such sidewalks are separated from the street by landscaping, only the setback for the garage door portion of the building shall be measured from the back of sidewalk. | |||||
ii. If sidewalks are detached or placed within an easement, building setback requirements shall be measured from the back-of-sidewalk or the property line, whichever is more restrictive, unless sidewalks are separated by landscaping in which case only the garage portion of the building shall be set back from the back of sidewalk or as otherwise approved through a conditional use permit.
(2) Multi-Family Residential: A private street in a multi-family residential development provided that the proposed street meets the general requirements as identified in subsection A and B, above and:
(a) The developable land that was saved by use of a private street must be utilized as open space. If there are lots to be owned individually, the open space shall be a common lot; and
(b) The private street serves less than 40 dwelling units.
(c) The application has complied with the requirements for a PUD including a traffic circulation plan.
(d) Standards for multi-family developments
i. Dimensional requirements for private streets shall be the same as permitted in this Code for service drives for multi-family developments (Section 11-07-04.3.B, Service Drives) when the use of the private street provides a similar function, such as the drive aisles and the common parking for the development are interrelated, as opposed to units that front on the private street and have individual garages or parking pads in front of each unit as is typical with townhouses or single family dwellings. If the private street does not provide a similar function, the standards of Section 11-07-04.2, Private Roads, shall apply.
ii. In developments of over 40 dwelling units, the dimensions of any private street shall be as recommended in the approved internal traffic circulation and as permitted in this Code for service drives for multi-family developments Section 11-07-04.3.B, Service Drives. Exception: This requirement may be waived in developments of over 40 dwelling units when it can be shown by the applicant that no section of roadway will exceed 240 vehicles per day in daily traffic.
iii. All utility easements shall be within, or immediately adjacent to, the private streets.
(3) Commercial/Industrial Developments: Private streets used solely for commercial/industrial purposes shall:
(a) Be a minimum of 24 feet in width.
(b) Not be required to have curbs, gutters, and sidewalks unless specifically required by Council.
6. Easements:
A. Easements shall be provided as required by the utilities, and other public services.
B. The Council may require applicants to reserve permanent public use easements for public access micro-pathways. Such easements shall be for future improvement and maintenance by either the city or the landowner or association. Any easement required under this section may be utilized in conjunction with or as an alternative to a public pedestrian access requirement under Section 11-07-04.4, Pedestrian Access.
7. Arterial And Collector Street Buffering: Landscaped buffer areas shall be provided where single family residential lots are adjacent to collector or arterial streets.
A. Perimeter Landscape Buffer:
(1) The buffer shall be located outside of any planned future right-of-way.
(2) The width of the buffer along arterial streets shall be a minimum of 30 feet, along collector streets it shall be a minimum of 20 feet.
(3) The buffer area may be located within the lot provided that:
(a) The depth of the lot is a minimum of 130 feet; and,
(b) In cases where the side lot line runs along an arterial or collector, the width of the lot is a minimum of 80 feet.
(4) Fences and walls shall not be placed within the buffer areas.
(a) The boundary farthest from the street of the landscape buffer;
(b) A minimum of five feet from the back of attached sidewalks;
(c) At the back of sidewalks separated from the curb by landscaping (provided the fence is not higher than four feet tall); or
(d) 15 feet from back of curb.
B. Frontage Road:
(1) Frontage roads, as permitted by the ACHD, and separated from a collector or arterial street by a ten foot wide landscaped median, may be permitted.
(2) The landscaped median shall be planted with trees and shrubs that at maturity will form a solid screen at least six feet high and a continuous tree canopy.
C. Alley-Loaded: The front lot line of a parcel may directly abut a collector or arterial street provided that an ACHD- approved alley is provided at the rear of such lots to provide direct lot access. Direct lot access to the collector or arterial is prohibited.
8. Alley (Public Or Private): Minimum alley width for a one-way alley shall be 12 feet. Minimum alley width for a two-way alley shall be 20 feet. Alley construction shall meet ACHD standards.