Chapter 17.25
DESIGN PRINCIPLES AND STANDARDS

Sections:

17.25.010    General provisions.

17.25.020    Streets.

17.25.030    Easements.

17.25.040    Lots.

17.25.050    Nonresidential subdivisions.

17.25.010 General provisions.

(a)    Compliance. The proposed subdivision shall conform to the comprehensive plan and official map.

(b)    Names. All subdivisions shall be named. The proposed name of the subdivision shall not duplicate, or too closely approximate phonetically the name of, any other subdivision in the area. The platting authority has final authority to designate the name of the subdivision and shall do so before final plat approval.

(c)    Debris and Waste. No cut trees, timber debris, earth, rock, stones, junk, rubbish, or other waste material of any kind created by development of the subdivision shall be left or deposited on any lot or street at the time of approval of the final plat, nor shall any be left or deposited in any area of the subdivision at the time of final approval of the required improvements.

(d)    Blocks.

(1)    The lengths, widths, and shapes of blocks shall be such as are appropriate for the locality and the type of development contemplated.

(2)    Blocks shall generally be of sufficient width to provide for two tiers of lots of standard depth. Exceptions may be permitted in blocks adjacent to major streets, waterways, and water bodies or other land features restrictive to further development.

(3)    For blocks greater than 2,200 feet in length or depth the planning commission serving as the platting authority may require easements and rights-of-way through the block to accommodate utilities, drainage and pedestrian traffic. [Ord. No. 1785, §1, 2-1-16.]

17.25.020 Streets.

(a)    Generally.

(1)    Standards. The arrangement, character, extent, width, grade and location of all streets shall conform to the comprehensive plan and shall be considered in their relation to existing and planned streets, to topographical conditions, to public convenience and safety, and in their appropriate relation to the proposed uses of the land to be served by such streets. Generally, and where not shown in the comprehensive plan, the arrangement and other design standards of streets shall conform to the provisions of this title.

(2)    Improvements. Roads shall be graded and improved to conform to applicable standards and specifications of this title and the standards adopted by the borough assembly and city of Ketchikan council and shall be approved as to design and specifications by the borough or city engineer in accordance with the approved construction plans.

(b)    Street Arrangement.

(1)    All streets shall be properly integrated with the existing and proposed system of thoroughfares and dedicated easements and rights-of-way as established in the comprehensive plan.

(2)    The arrangement of streets in new subdivisions shall make provision for the continuation of the existing streets in adjoining areas and where these adjoining areas are not subdivided the proper projection of streets shall be provided for.

(3)    Proposed streets shall be extended to the boundary lines of the tract to be subdivided, unless prevented by topographic or other physical conditions or designed as permanent deadend streets.

(4)    A gridiron street pattern need not necessarily be adhered to and the use of curvilinear streets, cul-de-sacs and loop streets shall be encouraged where such use will result in a more desirable layout.

(5)    Where a half-street is adjacent to the subdivision, the other half of the street shall be dedicated by the subdivider.

(6)    Major streets shall be properly integrated with the existing and proposed systems of major streets and highways.

(7)    Collector streets shall be properly related to the public transit system, to special traffic generating from facilities such as schools, churches, and shopping centers, to population densities and to major streets in which they feed.

(8)    Minor streets, which include local access and/or cul-de-sac streets, shall be laid out to conform as much as possible to topography, to discourage use by through traffic, to permit efficient drainage and sewer systems, and to require the minimum amount of street necessary to provide convenient safe access to property.

(c)    Access to Primary Roads.

(1)    Where a subdivision borders on or contains a limited access highway right-of-way or easement or an existing or proposed major street, the planning commission serving as the platting authority may require that access to such streets be limited by one of the following means:

a.    The subdivision of lots so as to back onto the primary arterial street and front onto a parallel local street; no access shall be provided from the primary arterial, and screening and/or a corridor of land shall be provided along the rear property line of such lots.

b.    A series of cul-de-sacs, U-shaped streets, or short loops entered from and designed generally at right angles to such a parallel street, with the rear lines of their terminal lots backing onto the major arterial.

c.    A marginal access or service road separated from the arterial by a corridor of land and having access thereto at suitable points.

(d)    Reserve Strips. Reserve strips controlling access shall be prohibited except where their control is definitely placed in the borough under conditions approved by the planning commission serving as the platting authority.

(e)    Street Design Standards.

(1)    Cul-de-Sacs. Streets designed to have one end permanently closed shall be no longer than 10 times the minimum lot width as determined by the zoning ordinance for residential zones and 600 feet for other zones, and shall be provided at the closed end with a circular turnaround having a turning radius not less than the right-of-way width of the cul-de-sac. Offset or T-shaped turnarounds providing an equivalent turning radius may be substituted.

(2)    Grade. The grade of streets shall not exceed 15 percent unless necessitated by exceptional topography and approved by the planning commission serving as the platting authority except public stairways and pedestrian trails which shall have no maximum grade. The minimum grade of all streets shall be not less than one percent.

(3)    Curves. The minimum sight distance with clear visibility, measured along the centerline, shall be at least 135 feet on major streets, 75 feet for collector streets and 50 feet on minor streets. All changes in street grades shall be connected by vertical curves of a minimum length equivalent to four times the algebraic difference in the rate of grade change in percent for major streets and collector streets and one-half of the minimum length for all other streets.

(4)    Intersections.

a.    Streets shall be laid out so as to intersect as nearly as possible at right angles. The intersection of two new streets at an angle of less than 70 degrees shall not be permitted except when necessitated by topography. An oblique street shall 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 planning commission serving as the platting authority.

b.    Proposed new intersections along one side of an existing street shall, wherever practicable, coincide with any existing intersections on the opposite side of such street. Street jogs with centerline offsets of less than 150 feet shall not be permitted, except where the intersected street has separated dual drives without median breaks at either intersection. Where streets intersect major streets, their alignment shall be continuous.

c.    Minimum curb radius at the intersection of two local streets shall be at least 20 feet; and minimum curb radius at an intersection involving a collector street shall be at least 25 feet.

d.    Intersections shall be designed with a minimum grade. In hilly or rolling areas, at the approach to an intersection, a leveling area shall be provided to ensure adequate traffic safety as determined by the borough or city engineer.

e.    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 (including trees) in connection with the grading of the public right-of-way or easement to the extent deemed necessary to provide an adequate sight distance.

f.    The cross-slopes on all streets, including intersections, shall be three percent or less.

(f)    Rights-of-Way.

(1)    The right-of-way of all streets shall be of the width specified in the comprehensive plan, or, if no width is specified therein, such rights-of-way shall be not less than the width specified below, unless necessitated by unusual topographic, physical or design features as determined by the planning commission serving as the platting authority.

Right-of-Way 

a. Pedestrian

10 feet

b. Alleys

20 feet

c. Arterials

80 feet

d. Collectors

50 feet

e. Local

 

1. Local access

40 feet

2. Cul-de-sac:

 

Lengths up to 500 feet

30 feet

Lengths greater than 500 feet

40 feet

3. Marginal access

40 feet

(2)    Excess Right-of-Way. Right-of-way widths in excess of the standards designated in this title 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).

(g)    Alleys.

(1)    Commercial and Industrial. Alleys shall be provided in all commercial and industrial districts, except that the planning commission serving as the platting authority may waive this requirement when other definite and assured provisions are made for service access, such as off-street loading and parking of adequate size, number, and design dimensions for the uses proposed are provided.

(2)    Residential. Alleys shall be discouraged in residential areas unless necessary because of topography or other exceptional circumstances.

(3)    Dead End. Dead-end alleys are prohibited except under unusual circumstances, and crooked and “T” alleys shall be discouraged. Where dead-end alleys are unavoidable, they shall be provided with adequate turnaround facilities at the dead end. [Ord. No. 1785, §1, 2-1-16.]

17.25.030 Easements.

(a)    Generally.

(1)    Easements and rights-of-way centered on rear lot lines shall be provided for utilities and other purposes where required by the planning commission serving as the platting authority and shall be at least 10 feet wide.

(2)    Where topographical or other conditions are such as to make impractical the inclusion of utilities within the rear lot lines, utilities shall be accommodated in the road rights-of-way or easements, or in permanent unobstructed easements at least 10 feet in width provided along front lot lines. All easements and rights-of-way shall be indicated on the plat.

(b)    Temporary Easements. An additional five-foot temporary easement, on each side of the existing easement, shall be granted for initial installation of utility systems when necessary. Said temporary easement shall be for a term not to exceed 60 consecutive days from the date of beginning of construction unless otherwise required by the planning commission serving as the platting authority.

(c)    Drainage Easements.

(1)    Where a subdivision is traversed by a watercourse, drainageway, channel or stream there shall be provided a storm water or drainage easement or right-of-way conforming substantially with the exterior boundaries of such watercourse, drainageway, channel or stream, and which may be of such additional width or construction, or both, as will be adequate as determined by the borough or city engineer. Wherever possible it is desirable that the drainage be maintained by an open channel with landscaped banks and adequate width for maximum potential volume of flow.

(2)    Where topography or other conditions are such as to make impractical the inclusion of drainage facilities within road rights-of-way, perpetual unobstructed easements at least 15 feet in width for such drainage facilities shall be provided across property outside the road right-of-way lines and with satisfactory access to the road. All easements shall be indicated on the plat. Drainage easements shall be carried from any road to a natural watercourse or to other drainage facilities.

(3)    When a proposed drainage system will carry water across private land outside the subdivision, appropriate drainage easements or other rights must be secured by the subdivider and indicated on the application.

(4)    Low-lying lands along watercourses subject to flooding or overflowing during storm periods, whether or not included in areas designated for dedication, shall be preserved and retained in their natural state as drainageways. [Ord. No. 1785, §1, 2-1-16.]

17.25.040 Lots.

(a)    Generally. The size, shape, and orientation of lots shall be appropriate for the location of the subdivision and for the type of development and use contemplated. The lot arrangement shall be such that there will be no foreseeable difficulties by reason of topography, or other conditions, in building on all lots in compliance with the zoning ordinance and Alaska Department of Environmental Conservation regulations and in providing driveway or stairway access to buildings on such lots from an approved street.

(b)    Lot Dimensions and Arrangement.

(1)    Lot dimensions shall not be less than the requirements of the zoning ordinance.

(2)    Depth and width of properties reserved or laid out for commercial and industrial purposes shall be adequate to provide for off-street parking and loading facilities required for the type of use and development contemplated, as established by the zoning ordinance.

(3)    Residential lots abutting on major streets and highways shall be platted with sufficient depth to permit adequate separation between the buildings and such traffic ways.

(4)    Residential lots should be designed with a suitable proportion between width and depth. Neither long and narrow, or wide and shallow lots are normally desirable. A two-to-three (2:3) ratio of width to depth is desirable.

(5)    All remnants of lots below minimum size left over after subdividing of a larger tract must be added to adjacent lots, rather than allowed to remain as nonconforming parcels.

(6)    Corner lots should be subdivided to permit full front yard setbacks on both streets as required by the applicable zoning requirements.

(7)    Lots at right angles to each other shall be avoided wherever possible.

(8)    Side lot lines shall be at right angles or radial to curving street lines whenever possible.

(9)    Where lots are created of a size larger than the minimum required area for the applicable zoning, the planning commission serving as the platting authority may require that such lots be arranged so as to allow further resubdivision and the opening of future streets where they would be necessary to serve such potential lots, all in compliance with the zoning and subdivision ordinances.

(10)    Lots shall follow municipal boundary lines wherever practicable, rather than crossing them.

(11)    Double frontage lots shall be avoided except where necessary to provide separation of residential development from traffic arterials or to overcome specific disadvantages of topography and orientation.

(c)    Lot Access.

(1)    Every lot shall front on or abut on a public street except where in the opinion of the planning commission serving as the platting authority adequate access by public stairways or pedestrian trails, public waterways or tidelands, or private drives is available.

(2)    Lots shall not, except when no other option is possible, derive access exclusively from a major or secondary arterial street.

(3)    Where driveway access from a major or secondary arterial street may be necessary for several adjoining lots, the planning commission serving as the platting authority may require that such lots be served by a combined access drive in order to limit possible traffic hazard.

(4)    Where possible, driveways should be designed and arranged so as to avoid requiring vehicles to back into traffic on a major or secondary arterial street.

(5)    Where the only designated access for a parcel or subdivision is a road maintained by a service area or where service-area-maintained roads provide for the only access to the subdivision or parcel that is required by the subdivision plat or other regulation or ordinance, the developer shall, through a plat note or similar means, require persons with an interest in those lots to support the annexation of the affected lots into the service affected area.

(d)    Twinhouse Dwelling Unit Lots. Any lot proposed to be developed with a twinhouse dwelling unit shall be designated on the plat as a twinhouse dwelling unit lot. No plat shall be approved which contains any designated twinhouse dwelling unit lot not connected to an adjacent designated twinhouse dwelling unit lot. No designated twinhouse dwelling unit lot may be resubdivided except in conjunction with its paired lot.

(e)    Townhouse Dwelling Unit Lots. Any lot proposed to be developed with a townhouse dwelling unit shall be designated on the plat as a townhouse dwelling unit lot. No plat shall be approved which contains any designated townhouse dwelling unit lot not connected to a series of two or more, but not exceeding seven adjoining designated townhouse dwelling unit lots. No designated townhouse dwelling unit lot may be resubdivided and no lot lines may be relocated or modified, except upon the prior review by the planning commission serving as the platting authority of the effect, if any, of such resubdivision or modification on adjacent or other townhouse dwelling unit lots, and compliance with such requirements or conditions as may be imposed by the planning commission serving as the platting authority to protect adjacent or other townhouse dwelling unit lots from the effects of such resubdivision or lot line modifications, including requiring adjustment of lot lines of adjacent or other townhouse dwelling unit lots. [Ord. No. 1785, §1, 2-1-16.]

17.25.050 Nonresidential subdivisions.

(a)    Standards. In addition to the principles and standards in this title and Alaska Statutes, which are appropriate to the planning of all subdivisions, the applicant shall demonstrate to the satisfaction of the planning commission serving as the platting authority that the street, parcel, and block pattern proposed is specifically adapted to the uses anticipated and takes into consideration other uses in the vicinity. The following principles and standards shall be observed:

(1)    Proposed industrial parcels shall be suitable in area and dimensions for the types of industrial development anticipated.

(2)    Street rights-of-way, easements, and surfaces shall be adequate to accommodate the type and volume of traffic anticipated to be generated thereupon.

(3)    Special requirements may be imposed by the planning commission serving as the platting authority based upon borough or city of Ketchikan engineering standards with respect to street, curb, gutter, and sidewalk design and construction.

(4)    Special requirements may be imposed by the planning commission serving as the platting authority based upon borough or city of Ketchikan engineering standards with respect to the installation of public utilities, including water, sewer, and storm water drainage.

(5)    Every effort shall be made to protect adjacent residential areas from potential nuisance from a proposed commercial or industrial subdivision, including the provision of extra depth in parcels backing up on existing or potential residential development and provisions for a permanently landscaped buffer strip when necessary.

(6)    Streets carrying nonresidential traffic, especially truck traffic, shall not normally be extended to the boundaries of adjacent existing or potential residential areas. [Ord. No. 1785, §1, 2-1-16.]