C. Street Design

C. Street Design

  1. Pavement Width
    Pavement widths shall be in accordance with details 1A and 1B. The minimum pavement width is 18 feet. This width is only applicable to dead end roads with an ADT below 160 which do not have any truck traffic. If a road does not meet these conditions then the minimum width shall be 20 feet. When curbing is required on rural roads such at intersections or steeper grades, then the pavement width shall be increased by four feet. Roads in areas zoned commercial or industrial shall vary based on accepted methods of design, number of lanes, the need for bike lanes, etc. In general the minimum width for theses roads shall be twenty-four feet.
  2. Curbing
    1. Use - Curbing is required in all business districts, along any commercial driveway, all intersections with arterial or collector roads, and where any road or ditch grade exceeds 8% or 6% when the developed length exceeds 250 feet. Use of curbing requires basins and culvert for drainage.
    2. Type - Granite curbing shall be utilized when curbing is installed. Bituminous or concrete curbing shall not be permitted as it is a substandard material for this use. If sidewalks are present vertical curbing is required. If there are no sidewalks than either vertical or sloped curbing is acceptable (See detail 7).
  3. Sidewalks - As a matter of pedestrian safety, sidewalks are required in the vicinity of schools, and in the Village or Business District. Sidewalks are to be at least five feet wide and shall be set back ten feet from the curb face or road shoulder. Sidewalks shall be concrete poured at 4" thickness with a 4000 3,000 PSI mix and 5 to 7 percent air entrainment (NHDOT Specification Section 608 Class B). Concrete shall be poured at no more than 4" slump. Acceleration ad mixtures shall not be used. The concrete shall be reinforced with ¾” fibrillated polypropylene fibers at 1.250 #/cy in accordance with the manufacturer’s instructions. A seven-foot wide, one foot (12") deep subbase of 1.5" gravel (NHDOT Item 304.3) shall be used. Compaction of the subbase shall be in accordance with Section 131-67.A(5). Expansion joints shall be installed in accordance with NHDOT standards at 4' spacing. Sidewalks shall be treated with Silane-Siloxane or equal. Sidewalks shall have a broom finish.
    Where sidewalks cross driveways they shall ramp down to the level of the driveway and comply with the ADA guidelines. Sidewalks greater than five feet in width may be required in these areas.
  4. Sight Distance, Minimum - All sight distances shall be computed for both vertical and horizontal curves.
    1. Level terrain - A minimum sight distance of two hundred feet is required.
    2. Rolling and hilly terrains - A minimum sight distance of one hundred and fifty feet is required.
  5. Dead End length and units, maximum - A dead end street shall not serve more than 35 dwelling units.
  6. Cul-de-sac turn around radius, minimum - See Detail 4.
  7. Off-Street Parking - The pavement widths as detailed earlier are predicated on there being no on-street parking. As such off-street parking of two spaces per lot or unit shall be required.
  8. Driveways - Driveways shall be located and their entrances designed as a part of street design. See Detail 5. The minimum standards which must be met are as follows:
    1. Drainage analysis, design, full paving and curbing may be required all the way to the building site if the driveway is likely to divert runoff to the roadside or cause flow into the street.
    2. Minimum width of ten foot driveway for residential, fourteen feet for one-way nonresidential, and twenty feet for two-way non-residential. Maximum width of eighteen foot driveway for residential and thirty-six foot driveway for non-residential.
    3. 90 degree +/- 15 degrees intersection with street.
    4. Intersection flares - at minimum single family driveways shall provide a fifteen foot curb radii or five-foot wide by ten-foot long straight flare.
    5. Driveway grades shall comply with Detail 5.
    6. Commercial driveways require curbing and a minimum radius of 25 feet.
    7. Unpaved driveways will require paved aprons extending at least to the ditch line but not less than 15 feet for residential driveways and 25 feet for commercial driveways.
    8. No more than 1 curb cut is allowed for residential lots (see also 123-20).
    9. Also see Table 2 for driveway site-distance requirements and location relative to intersections and other driveways and Detail 5 for other requirements.
    10. In accordance with RSA 236:13 and the legislative authority cited in §131-1 of this chapter, prior to any modification of an existing driveway or construction of a new driveway that deviates from the design shown on an approved subdivision plan or site plan or construction of a new driveway that is not adequately represented on an approved subdivision plan or site plan the property owner must first secure a driveway permit. The Planning Board hereby delegates the authority to administer and issue such permits in accordance with this Chapter to the Board of Selectmen. This includes the issuance of such permits and the adoption of the forms and administrative policies to administer same.
    11. In accordance with the legislative authority cited in §131-1 of this chapter, prior to any work, other than that represented in a driveway permit issued pursuant to §131-68.C.8. (j), by work performed by contractors, developers, utilities or others doing work on town properties or town roads must first secure a construction permit. The Planning Board hereby delegates that authority to administer and issue such permits in accordance with this Chapter to the Board of Selectmen. This includes the issuance of such permits and the adoption of the forms and administrative policies to administer same.
  9. Utilities- All buried utilities shall be located beyond the ditch line. All above-grade utility facilities such as transformers, pedestals, and sector cabinets shall be located at the right of way line.
  10. Water and Sewer Utilities – See 131-48. Hydrants to be located behind the ditch line but not less than 10 feet from the travel way.