§ 148-6 DESIGN STANDARDS.
   (A)   General requirements.
      (1)   The subdivision layout shall conform in all essential respects with the official transportation plan and other aspects of the adopted comprehensive plan for the town.
      (2)   The subdivision layout shall be in full compliance with the provisions of the zoning districts in which it is located.
      (3)   The subdivision layout shall be designed in accordance with the principles and standards contained in this section and with the objective of achieving the most advantageous development of the subdivision and adjoining areas.
   (B)   Suitability of land.
      (1)   Land subject to periodic flooding shall not be subdivided for residential occupancy nor for any other use which might involve danger to health, life, or property or aggravate the flood hazard, and the land within any proposed subdivision shall be reserved for uses which will not be endangered by periodic or occasional inundation.
      (2)   A plat for the subdivision of land with poor drainage or other adverse physical conditions will be considered for approval only if the subdivider shall agree to make whatever improvements are necessary, in the judgment of the Planning Commission, to render the land safe and otherwise acceptable for development.
   (C)   Street layout.
      (1)   The street layout shall be designed to create desirable building sites while respecting existing topography, minimizing street grades, avoiding excessive cuts and fills, and preserving trees to the maximum extent possible.
      (2)   Streets shall be spaced to allow for blocks meeting the dimensional requirements contained herein and to minimize the number of intersections with existing or proposed major thoroughfares.
      (3)   Where the subdivision adjoins or embraces any part of a major thoroughfare as designated on the transportation plan, the layout of the subdivision shall provide for the platting and dedication of the part of the major thoroughfare in the location and at the width indicated on the plan, except that the subdivider shall not be required to dedicate that part of the major thoroughfare which is in excess of 80 feet in width.
      (4)   Wherever deemed desirable to the layout of the subdivision and adjoining areas, the Planning Commission may require the planning and dedication of one or more collector streets or parts thereof to serve the subdivision.
      (5)   Minor residential streets intended primarily for access to individual properties shall be so arranged as to discourage their use by through traffic.
      (6)   Streets shall be laid out to intersect one another at as near to right angles as topography and the limiting factors of good design will permit, and no street shall intersect another street at an angle of less than 60 degrees.
      (7)   Proposed streets in the subdivision shall provide for the continuation of existing, planned or platted streets on adjacent tracts, unless the continuation shall be prevented by topography or some other physical condition, or unless the extension is found by the Planning Commission to be unnecessary for the coordination of development between the subdivision and the adjacent tract.
      (8)   Where the Planning Commission deems it desirable or necessary to provide access to adjacent tracts not presently subdivided, proposed streets in the subdivision shall be extended to the boundary lines with the adjacent tracts, and temporary turnarounds shall be provided at the ends of the streets by means of temporary easements or otherwise.
      (9)   Where the subdivision abuts or contains a primary highway as designated on the transportation plan, the Planning Commission may require that measures be taken to reduce the impact of heavy traffic on the residential lots abutting or fronting upon the highway and to afford separation of through and local traffic through one of the following means. The choice of the most appropriate method of accomplishing the desired purpose in a specific instance shall be made by the Planning Commission, giving consideration to topography and other physical conditions, the character of existing and contemplated development in the subdivision and its surroundings and other pertinent factors. Measures to reduce the impact of heavy traffic on residential lots abutting or fronting upon the primary highway may be accomplished through one of the following methods:
         (a)   By providing vehicular access to the lots by means of a service drive separated from the major thoroughfare by a planting strip and connecting therewith at infrequent intervals; or
         (b)   By designing reverse-frontage lots having access only from a parallel minor street or from cul-de-sac or loop streets and with vehicular access to the lots from the major thoroughfare prohibited by deed restrictions or other means.
      (10)   Cul-de-sac streets, generally not exceeding 600 feet in length, shall be permitted where they are necessitated by topographic conditions or where, in the judgment of the Planning Commission, they are appropriate to the type of development contemplated.
      (11)   Alleys shall be provided in commercial and industrial areas unless adequate access to parking and loading areas is provided by other means. Alleys will not be permitted in residential areas, except for providing rear access to row dwellings or where required by topographic or other unusual conditions. In the absence of alleys, easements will be required for utility lines or drainage facilities.
      (12)   Half streets will be prohibited except where they are essential to the reasonable development of the proposed subdivision in conformity with the other requirements of these regulations and where the Planning Commission finds that it will be practicable to require dedication of the remaining half when the adjoining property is subdivided. Wherever a half street adjoins the proposed subdivision, the remaining half of the street shall be platted within the subdivision.
      (13)   Private streets shall not be permitted in any proposed subdivision.
   (D)   Street design standards.
      (1)   Right-of-way widths. Right-of-way widths for primary and secondary highways shall be as designated in the transportation plan and, in any case, not less than 150 feet for primary highways and 80 feet for secondary highways: provided, however, that widths above these minimums may be required by state officials to meet particular traffic conditions. Right-of-way widths for other street types shall be not less than 60 feet for collector streets and commercial and industrial areas, 50 feet for minor streets in residential areas, 40 feet for service drives, and 16 feet for alleys.
      (2)   Roadway widths.
         (a)   Roadway widths for primary and secondary highways shall be not less than the minimum specified by state officials, but in any case not less than 24 feet with ten-foot shoulders.
         (b)   Roadway widths for other street types shall be not less than the following:
            1.   For collector streets and minor streets in multiple-family residential, commercial, and industrial areas, the roadway width shall be not less than 40 feet with curbs and gutters, except that streets serving lots of one acre or more may, with the approval of the Planning Commission, have a minimum roadway width of 22 feet with eight-foot shoulders;
            2.   For minor streets in single-family residential areas and service drives, the roadway width shall be not less than 30 feet with curbs and gutters, except that streets serving lots of one acre or more may, with the approval of the Planning Commission, have a minimum roadway width of 20 feet with six-foot shoulders on each side for minor streets and on one side for service drives; and
            3.   For alleys, the roadway width shall be not less than 12 feet.
         (c)   The town Planning Commission may reduce the street standards of width in division (D)(2)(b)1. and 2. above in accordance with good planning techniques.
      (3)   Cul-de-sac streets. Cul-de-sac streets shall have a circular turnaround of not less than 100 feet in diameter lo the street line and with a roadway of not less than 80 feet in diameter, unless the Planning Commission approves a T- or Y-back-around.
      (4)   Street grades. Street grades shall not exceed 5% for primary and secondary highways and collector streets and 8% for minor streets, service drives, and alleys, except that the Planning Commission may permit a variation of not greater than 2% from these maximums where topographic conditions warrant. Street grades shall be not less than 0.5% at the gutter. All changes in street grades of more than 1% shall be connected by vertical curves with a minimum length of 50 feet or 15 times the algebraic difference in the change in grade, whichever is greater.
      (5)   Curvature. The radius of curvature on the center line shall be not less than 400 feet for primary and secondary highways, 300 feet for collector streets and 100 feet for minor streets, service drives, and alleys. Between reversed curves, either of which has a radius of less than 200 feet, there shall be a tangent section at least 100 feet in length.
      (6)   Intersections. Each property corner at street intersections shall be rounded off by an arc, the radius of which shall be not less than 20 feet, except that in a business area, a chord may be substituted for the arc. Curbs at street intersections shall be rounded off concentrically with the property lines. The design of the intersection should provide clear sight distance for oncoming vehicles, and there should be a suitable leveling of the street grade within and approaching the intersection.
   (E)   Blocks.
      (1)   Residential blocks shall normally not exceed 1,300 feet in length nor be less than 500 feet in length between street lines. In any residential block more than 800 feet in length, a crosswalkway of not less than ten feet in width may be required, where necessary, to provide convenient access to schools, playgrounds, shopping centers and other community facilities.
      (2)   Residential blocks shall normally be of sufficient width to provide two tiers of lots of appropriate depth.
      (3)   Blocks for business or industrial use shall be of the length and width as may be necessary to serve their prospective use, including making adequate provision for off-street parking and for the loading and unloading of delivery vehicles.
      (4)   Irregularly shaped blocks indented by cul-de-sac or looped streets and containing interior parks or playgrounds will be acceptable when they are properly designed, including making provision for adequate parking and for the maintenance of the public or joint use recreation area.
   (F)   Lots.
      (1)   Lot arrangement, design, and orientation shall be such that all lots will provide satisfactory building sites which are properly related to topography and the character of surrounding development.
      (2)   The dimensions and areas of all lots shall comply with the requirements of the zoning district in which they are located, except that in any case where public water supply and/or public sewerage is not available or is not to be provided, all residential lots shall comply with the minimum lot dimensions and areas established by the Health Officer or state Department of Health, after appropriate water percolation tests, where these requirements are greater than required under the zoning regulations.
      (3)   Excessive lot depth in relation to lot width shall be avoided. A ratio of depth to width of two to one (2:1) shall be considered a desirable maximum.
      (4)   Corner lots shall desirably have extra width to permit an appropriate building setback from both streets in accordance with the zoning regulations.
      (5)   Every lot shall abut upon and have access to a public street.
      (6)   Double-frontage and reverse-frontage lots shall be avoided, except where their use is essential to overcoming special topographic problems or to separating residential development from heavy street traffic.
      (7)   Residential lots fronting or abutting on major thoroughfares shall desirably have extra lot depths and deeper building setbacks.
      (8)   Lots adjoining a railroad line shall have extra lot depth and shall provide for an appropriate means of buffering the lots from the railroad line.
      (9)   Insofar as possible, side lot lines shall be substantially at right angles or radial to the street line, except where a variation to this requirement will provide an improved street and lot layout.
      (10)   The size and shape of lots intended for single-family residential use shall be sufficient to permit the ultimate provision of a garage on each lot, except that the Planning Commission may permit the grouping of garages into a compound serving several lots.
   (G)   Easements.
      (1)   Where alleys are not provided in appropriate locations, easements of not less than ten feet in width shall be provided, where necessary, to meet public utility requirements. Easements of greater width may be required along lot lines or across lots, where necessary, for the extension of trunk sewers or other primary utility lines.
      (2)   Where a proposed subdivision is traversed by any stream, watercourse, or drainageway, the subdivider shall make adequate provision for the proper drainage of surface water, including the provision of easements along the streams, watercourses, and drainageways.
      (3)   Utility easements in private rights-of-way or in joint-use recreation areas may be permitted at the discretion of the Planning Commission if the design considerations of the proposed subdivision warrant the easements.
      (4)   No building or structure shall be constructed on any easement without the written authorization of the Mayor and Council.
   (H)   Public sites and open spaces.
      (1)   Where the proposed subdivision includes lands proposed for use as parks, playgrounds, playfields, public landings, or school sites under the comprehensive plan, the subdivider shall indicate the location of the lands on the subdivision plat and shall dedicate the lands to the appropriate jurisdiction.
      (2)   Where deemed essential by the Planning Commission considering the type and size of development proposed in the subdivision, the subdivider may be required to dedicate sites and recreational facilities of a character, extent, and location suitable to meeting the needs of the development. In lieu of dedicating the additional areas, they may be reserved for the common use of all property owners in the proposed subdivision through deed restrictions.
(Prior Code, § 148-6) (Ord. passed 5-3-1975)