Town of Conway, NH Road Standards

Right-of-way width. The minimum ROW width shall be 60 feet for rural areas and 66 feet for urban areas. Greater width may be required if, in the opinion of the Planning Board, it is needed to provide adequate room for the proposed street, sidewalks if required, street utilities, drainage, grading and snow storage.

Clearing and grubbing. The entire limits of the road bed shall be cleared of all trees, stumps, roots, boulders and like materials. In addition, all topsoil and unsuitable materials must be removed from the limits of the road bed. In no case shall the limit of clearing and grubbing extend less than 10 feet from the road shoulder.

Geotextile placement. Except where both the native soil and embankment material contain less than 12% fines (#200 sieve or finer), a woven geotextile shall be placed at subgrade. Where the embankment material contains less than 12% fines, the geotextile shall be positioned at the base of the embankment. The geotextile shall be equivalent to, or stronger than, Mirafi 500X.

Embankment material. In areas of fill, unsuitable material or in the presence of water, the construction of an embankment will be required to bring the level of the street up to that which is needed to place the aggregate subbase. The embankment shall be brought to subgrade in horizontal lifts with common material which is suitable for road construction as approved by the Town. Testing of the materials shall be done at the applicant's expense.

Aggregate base and subbase materials. The aggregate subbase course shall consist of 12 inches of gravel, NHDOT Item 304.2, and the aggregate base shall consist of six inches of crushed gravel, NHDOT Item 304.3. Testing of the materials' gradation (AASHTO T27 and T11) and proctor (AASHTO T99) shall be done at the applicant's expense. See Detail 1.[1]These are minimum standards. The amount of aggregate base and subbase materials shall be increased in areas of poor soils and for roads carrying commercial/industrial traffic. A geotechnical investigation may be required.

[1]

Editor's Note: The details are included as an attachment to this chapter.

Compaction. Compaction is required for the embankment, aggregate base and subbase materials. It shall be performed by using vibrating rollers and water in lifts of no greater than 12 inches. Compaction shall be performed until the required density is achieved. Density shall be determined by AASHTO T238 method and shall not be less than 95% of the maximum density determined in accordance with AASHTO T99.

Pavement.

Binder course: a two-inch to three-inch lift of pavement (see Details 1A and 1B[2]) meeting New Hampshire Standard Specifications for Road and Bridge Construction, Division 400, Section 401.

[2]

Editor's Note: The details are included as an attachment to this chapter.

Wearing course. A one-inch to 1 1/2-inch lift of pavement (see Details 1A and 1B[3]) meeting New Hampshire Standard Specifications for Road and Bridge Construction, Division 400, Section 401.

[3]

Editor's Note: The details are included as an attachment to this chapter.

Pavement shall not be installed when the outside air temperature is below 40° F., nor when the road base temperature is below 40° F. The temperature of pavement mix relative to road base temperature when spread shall be in accordance with Table 3.[4] Pavement shall not fall below 185° F. prior to the completion of rolling. Pavement shall not be installed when the subgrade is frozen or the grades are incorrect. On newly constructed roads, the base course and the wearing course shall not be installed in the same season.

[4]

Editor's Note: Table 3 is included as an attachment to this chapter.

The wearing course must be installed within two calendar years of the installation of the base course.

[Added 7-28-2016]

Shoulders: in accordance with Detail 1.[5] Shoulders shall be installed on both sides of the street and shall consist of modified crushed gravel, NHDOT Item 304.33. When curbs are installed, this section shall not apply.

[5]

Editor's Note: The details are included as an attachment to this chapter.

Loaming and seeding.

All remaining disturbed areas within the right-of-way shall have four inches of loam, which is free of stumps, roots and other unsuitable material, installed.

All remaining disturbed areas within the right-of-way shall be fertilized and seeded in accordance with Section 646 of the NHDOT specifications, except that all mulch shall be anchored with a tackifier at a minimum.

The seeding of slopes and ditches shall require the use of erosion-control matting.

Cross-sectional grading of slopes.

Cross-sectional elements shall be in accordance with Details 1A and 1B.[6]

[6]

Editor's Note: The details are included as an attachment to this chapter.

Drainage.

Adequate disposal of surface water shall be provided. Provisions must be made for maintaining natural watercourses and, unless a drainage easement is provided, limiting the peak runoff from new or improved roads to the existing conditions during both the two- and twenty-five-year rainfall events. Road cross-culverts and water flow in the curbline shall be designed for at least the twenty-five-year event and driveway culverts for at least the ten-year event. Water flow along the curbline shall not extend more than four feet into the travel lane. Drainage calculations must be submitted to the Planning Board for its approval. For comparison of existing conditions and proposed conditions, or where hydrograph routing is necessary, the SCS TR-20 methods shall be utilized. For storm drainage system sizing where the drainage area is less than 200 acres, the Rational Method or SCS methods may be utilized. For storm drainage system sizing where the drainage areas are greater than 200 acres, the Potters Small Watershed Analysis, SCS methods, or other methods as approved by the Planning Board or its representative may be used.

All road culverts shall be at least 15 inches in diameter, and all driveway culverts shall be at least 12 inches in diameter. Culverts shall be corrugated metal pipe (complying with AASHTO M36, Type III) or reinforced concrete pipe (Class III or higher complying with NHDOT Section 603), or HDPE plastic pipe (by Hancor or ADS complying with AASHTO M294, Type S). No aluminum shall be allowed. See Detail 6A.[7]

[7]

Editor's Note: The details are included as an attachment to this chapter.

When pipe systems are included in a street design, plan/profile sheets shall be required for the systems showing proper sizing, slopes, inverts, etc.

When roadside drainage ditches are used, they shall be in accordance with Details 1A and 1B.[8] Riprap-lined roadside ditches are allowed only behind curbed roads. In such cases, the riprap shall extend no closer than four feet to the back of the curb. Cross-culverts and/or closed storm drain systems shall be used to limit the flow in ditches to 10 cubic feet per second (cfs) and velocity to three feet per second (fps) in grass-lined ditches. In no case shall the ditch length exceed 600 feet. Refer to Subsection C(2) for other conditions that require the use of curbing, catch basins and closed storm drains. Permanent turf reinforcement mats (TRMs) are not allowed in roadside ditches.

[8]

Editor's Note: The details are included as an attachment to this chapter.

The street crown, center to shoulder, shall be 1/4 inch per foot. Superelevation shall be required where the ADT is greater than 400. When designing a superelevated street, the superelevation rate shall not exceed 3/4 inch per foot and must be accompanied by engineering calculations.

Headwalls with properly designed cutoffs shall be required at the inlet end of all culverts. See Detail 2.[9] For driveway culverts, prefabricated end sections with toe plates may be used in lieu of headwalls.

[9]

Editor's Note: The details are included as an attachment to this chapter.

Underdrains shall be used under ditches where the seasonal high water table is within three feet of the subgrade elevation. Where the road runs nearly perpendicular to the existing contours, additional underdrains shall be installed laterally across the road and spaced no greater than 100 feet apart. Where the road runs nearly diagonal to the contours, underdrains shall be installed laterally across the road and spaced no greater than 200 feet apart. Underdrain shall be installed in accordance with Detail 3.[10] Storm drain pipes may be perforated in lieu of providing separate underdrain pipes. Perforations in storm- drain pipes shall be positioned at 10:00 and 2:00, and the depth of flow in the pipe shall be kept below the perforations.

[10]

Editor's Note: The details are included as an attachment to this chapter.

Infiltration devices shall require: pretreatment of the stormwater before infiltration; test pits demonstrating that the bottom of the devices are at least three feet above the seasonal high groundwater table; the bottom of the entire infiltration surface to be at least three feet below finished grade; and the infiltration area to be located outside the travel way and shoulder. In areas of SCS Adams soils, confirmed by test pitting, the exfiltration velocity may be assumed to be 0.0022 cfs/sf. In all other areas, the exfiltration velocity shall be determined by field permeability testing or established correlations to grain-size distributions, with a 1.5 factor of safety applied.

Drainage easements shall be provided where the peak rate of runoff will increase and/or where the runoff flow type changes to concentrated flow. Drainage easements shall extend from point of increased flow and/or the point the flow becomes concentrated to the point the runoff reaches an NHDES jurisdictional wetland/channel. Drainage easements are not required within the road right-of-way.

For subdivisions, the assumed impervious area per building lot shall not be less than 5,000 square feet and the assumed cleared area per building lot shall not be less than 10,000 square feet. The assumed impervious and cleared areas shall be stated on the subdivision plan with a note specifying that if the actual impervious and/or cleared areas exceed the assumptions, the lot owner shall revise the drainage analysis accordingly and provide measures to limit the flow to those assumed in the drainage design. Note: impervious area includes both paved and compacted gravel surfaces.

Street design.

Pavement width. Pavement widths shall be in accordance with Details 1A and 1B.[11] 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 as 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 these roads shall be 24 feet.

[11]

Editor's Note: The details are included as an attachment to this chapter.

Curbing.

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.

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, then either vertical or sloped curbing is acceptable. (See Detail 7.[12]).

[12]

Editor's Note: The details are included as an attachment to this chapter.

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 10 feet from the curb face or road shoulder. Sidewalks shall be concrete poured at four inches' thickness with a 3,000 PSI mix and 5% to 7% air entrainment (NHDOT Specification Section 608 Class B). Concrete shall be poured at no more than four inches' slump. Acceleration ad mixtures shall not be used. The concrete shall be reinforced with 3/4-inch fibrillated polypropylene fibers at 1.50 #/cy in accordance with the manufacturer's instructions. A seven-foot-wide, one-foot (twelve-inch) deep subbase of 1.5-inch gravel (NHDOT Item 304.3) shall be used. Compaction of the subbase shall be in accordance with Subsection A(5). Expansion joints shall be installed in accordance with NHDOT standards at four-inch 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.

Sight distance, minimum. All sight distances shall be computed for both vertical and horizontal curves.

Level terrain: a minimum sight distance of 200 feet is required.

Rolling and hilly terrains: a minimum sight distance of 150 feet is required.

Dead-end length maximum. A dead-end street shall not exceed 1,000 feet in length.

[Amended 3-14-2019]

Cul-de-sac turnaround radius, minimum. See Detail 4.[13]

[13]

Editor's Note: The details are included as an attachment to this chapter.

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.

Driveways. Driveways shall be located and their entrances designed as a part of street design. See Detail 5.[14] The minimum standards which must be met are as follows:

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.

Minimum width of 10 feet for residential, 14 feet for one-way nonresidential, and 20 feet for two-way nonresidential; maximum width of 18 feet for residential and 36 feet for nonresidential.

Ninety-degree +/- 15° intersection with street.

Intersection flares: At a minimum, single-family driveways shall provide a fifteen-foot curb radius or a straight flare five feet wide by 10 feet long.

Driveway grades shall comply with Detail 5.[15]

[15]

Editor's Note: The details are included as an attachment to this chapter.

Commercial driveways require curbing and a minimum radius of 25 feet.

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.

(h)

No more than one curb cut is allowed for residential lots. (See also § 110-20.)

(i)

See also Table 2 for driveway site-distance requirements and location relative to intersections and other driveways and Detail 5 for other requirements.[16]

[16]

Editor's Note: Table 2 and the details are included as attachments to this chapter.

(j)

In accordance with RSA 236:13 and the legislative authority cited in § 130-1 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 to the Board of Selectmen the authority to administer and issue such permits in accordance with this chapter. This includes the issuance of such permits and the adoption of the forms and administrative policies to administer same.

(k)

In accordance with the legislative authority cited in § 130-1 of this chapter, prior to any work, other than that represented in a driveway permit issued pursuant to Subsection C(8)(j), 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 to the Board of Selectmen the authority to administer and issue such permits in accordance with this chapter. This includes the issuance of such permits and the adoption of the forms and administrative policies to administer same.

[14]

Editor's Note: The details are included as an attachment to this chapter.

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.

Water and sewer utilities. See § 130-47. Hydrants shall be located behind the ditch line but not less than 10 feet from the travel way.

§ 130-67 Miscellaneous standards.

Highway bounds and signs.

Granite highway bounds, at least 24 inches in length and four inches square, shall be set at all points of street intersections, at all points of change of direction (PC/PT), at points along tangents no more than 800 feet and as per proper surveying standards. Discs shall be set in the top of the bounds and shall be stamped with numbers corresponding to those indicated on the metes-and-bounds plan.

All projects shall conform to the Manual on Uniform Traffic Control Devices, latest edition.

Consultants. The Planning Board or Board of Selectmen may hire consultants to review plans, perform inspections and/or perform other duties related to the project as it deems appropriate. All costs of said consultants shall be paid by the applicant.

Inspections.

Initial inspection shall take place upon submission of proposed road plans. It is the responsibility of the owner(s) to have roads laid out with center-line grade stakes at every half station. The Board of Selectmen will notify the owner(s) of the date of inspection.

Prior to the start of the work, a preconstruction meeting will be held to review procedures, identify responsibilities and discuss Town requirements. The contractor and the contractor's superintendent shall attend the preconstruction meeting. The following items shall be submitted at or before the preconstruction meeting:

Two copies of the approved plans;

USEPA NPDES notice of intent (NOI) and stormwater pollution prevention plan (SWPPP);

Surety of work;

Testing and inspection fees; and

Project schedule.

The Town and the Town's representatives shall have full access to the site when the work is in preparation, during construction and after completion. They may observe the work on a periodic or full-time basis. The Town must be present during the installation of utilities, drainage pipes, geotextile and pavement and must observe the work at other specified stages.

The applicant shall notify the Office of the Town Engineer two business days prior to the required inspections. Upon notification by the applicant, the Town Engineer or designee shall perform the following inspections within 48 hours:

Cleared and grubbed: roadway is clear and grubbed down to native soil, free of loam or other unsuitable materials prior to the placement of any fill.

Drainage: installation of pipe, culvert, basins, etc.

Embankment: placing and compacting the embankment material.

Geotextile: Geotextile is laid.

Aggregate subbase: Aggregate subbase is installed and compacted.

Aggregate base: Aggregate base is installed and compacted.

Pavement installation: The applicant must notify the Town of the date(s) on which pavement will be installed. The Town must give approval prior to the placement of pavement. The Town must be present during the installation of pavement.

(h)

Utilities: installation of conduits, cables, pipe, and warning tape for electric, water, sewage, etc. The Town must be present during the installation of utilities.

(i)

As-built drawings shall be maintained on a daily basis; weekly inspections will be conducted.

(j)

Final inspection. After the submission of as-built drawings and prior to the release of the surety the Town shall conduct a final inspection. All items from the Town's punch list shall be addressed prior to the acceptance of the work.

Failure to notify the Town or its designated representative of said inspection points shall give the Town the right to reject the work and require reconstruction.

The Town and/or its designated representative shall at all times have access to the site for the purpose of performing inspections.

The cost of inspection and testing shall be paid by the applicant(s).

Surety of work.

Proper surety in the form of cash or bonds must be submitted to the Town to insure the completion of work. No work shall start on the property until proper surety is in place. The surety amount shall be 115% of the current estimated cost.

A utilized cost estimate shall be submitted for approval prior to the surety being accepted. The cost estimate shall include the costs of inspection and testing. Surety may be drawn down no more often than monthly. In no case shall the surety be drawn below 10% until the completed road has successfully stood for one year.

The surety may be used by the Town to repair work which has failed or was not performed in accordance with the plans and specifications, to restore the site should the project default, to cover the cost of testing and inspections and to cover legal or other fees the Town may incur during the collection process.

Street acceptance. No street will be accepted by the Town until such time as all improvements have been carried out as shown on the final plat, in accordance with the requirements of these regulations and subject to any conditions established by the Planning Board at the time of final plat approval. In addition, the following conditions shall be met prior to the Selectmen recommending a street for acceptance:

At least 85% of all buildings to be built on lots fronting on the road shall be fully constructed and ready for occupancy.

The valuation along said street shall be a minimum of $2,000,000 per mile.

Street construction shall have been complete for a minimum of 18 months.

The standards of this chapter shall have been met.

At least 1,000 feet of street shall be proposed for acceptance except when the proposal is for a generally straight extension of an existing Town street.

A fee-simple deed shall be submitted prior to acceptance. A metes-and-bounds description, prepared by a New Hampshire licensed surveyor, shall be submitted to the Town. Accompanying the legal description shall be a certification by the owner's surveyor that the right-of-way bounds have been set at the locations shown on the street design plan.

No road will be considered unless accessible via a Town or state roadway.

All petitions for road layout must be made before October 1 of each year. Petitions shall be signed by at least 25 Conway registered voters.

When there are no records indicating that the Town witnessed the road construction (i.e., inspection reports, sieve analysis, compaction tests, etc.), road corings to investigate subgrade shall be performed and paid for by the applicant. Testing will not be done between November 1 and May 1. The following testing shall be performed:

Pavement and aggregate testing at one-hundred-foot spacing;

Aggregate base density and percent compaction at two-hundred-foot spacing;

Aggregate base sieve analysis at four-hundred-foot spacing; subgrade sieve analysis at four-hundred-foot spacing; and

Aggregate base proctor tests at eight-hundred-foot spacing (composite from corings).

Betterment projects shall conform to the provisions of RSA 231:28 through 231:33. All costs of betterment engineering shall be paid for by the applicant. Betterment periods shall be no longer than 10 years.

(11)

Upon acceptance of the road, a maintenance bond shall be provided to reserve funds to repair or reconstruct streets which have become damaged due to latent defects in the street construction. The maintenance bond shall remain in effect until two years after acceptance and the bond value shall generally be $20 per linear foot of roadway accepted. The bond value is intended to approximately equal 10% of the cost to fully reconstruct the road.

Waivers.

Waivers to any section may be requested. All waiver requests must be submitted in writing. The Planning Board shall not approve waivers unless it shall make findings based upon evidence presented to it in each specific case that:

The granting of the waiver will not be detrimental to the public safety, health or welfare or injurious to other properties located nearby.

The granting of the waiver shall not permit construction of a lesser quality or create a structure requiring greater maintenance.

The granting of the waiver shall not have the effect of nullifying the intent and purpose of these regulations.

Upon receiving the request, the Planning Board shall evaluate the arguments, review the possible precedents which the decision may set, and shall vote to approve or disapprove the request.

More stringent provisions. In all cases of conflict between this and other Town or state regulations, the stricter regulations shall apply.

Minimum data required on street design plans.

The applicant shall submit two complete sets of street design plans for the Planning Board's review. The applicant shall also submit two copies of any revisions made to the plans for approval. The plans shall be submitted on twenty-two-inch by thirty-four-inch plan/profile paper and shall be done with a horizontal scale of one inch equals 40 feet and a vertical scale of one inch equals 10 feet.

Data requirements:

Title showing the name of the subdivision, name of the street and name of the owner, date (day, month, year), revision history, scale and name and seal of an engineer licensed in the State of New Hampshire.

Right-of-way lines.

Slope and drainage easements.

All center-line data (tangent lengths and bearings, curve data and stationing).

Edge-of-pavement lines.

Cross sections at each half station.

Existing grade at each half station (on profile and cross section).

(h)

Proposed grade at each half station (on profile and cross section).

(i)

Length of vertical curves and data (on profile).

(j)

Sight distance of horizontal and vertical curves.

(k)

Design speed.

(l)

Type of terrain considered to control design.

(m)

Average daily traffic (ADT) based on the ITE Trip Generation Manual, 1987.

(n)

Design year based on 10th year after opening year.

(o)

Drainage structure location and inverts, station, skew, length, slope and end treatment.

(p)

Benchmarks not more than 500 feet apart.

(q)

Utility locations and details.

(r)

Specific material specification or reference.

(s)

A detailed engineer's opinion of construction cost.

(t)

A notarized letter fixing the legal responsibility for maintenance of the streets.

(u)

A grading plan showing existing and proposed contours at a minimum of two-foot frequency within the right-of-way.

(v)

General notes for inspections (see Subsection C for inspection requirements).

(w)

Driveway layout with the street right-of way and spot elevations at edge of pavement, ditchline/gutter, and right-of-way line.

(x)

Erosion and sediment control plan with project-specific construction sequence.

As-builts.

In order to ensure the proper construction of development streets, as-Built drawings shall be presented to the Selectmen or their designee for their review prior to final draw-down of the surety for the project. These drawings must be maintained on a daily basis and will be inspected weekly.

Except for those referred to above, the Planning Board does not require as-built subdivision plans, nor will it stamp and sign such plans. The only as-built subdivision plans which the Board will stamp and sign is the plan showing the location of structures on condominium property. Such plans shall:

Be certified to be correct and stamped by a New Hampshire licensed land surveyor

Be accompanied by certificates of occupancy, if applicable;

Clearly identify in the title block exactly what the as-built plan is approving; and

Have the following plat note printed on each sheet: "These as-built plans are pursuant to, and without modification of, the original Planning Board approval."

Submit a metes-and-bounds plan prepared by a New Hampshire licensed land surveyor showing the following items:

Platted rights-of-way.

Bearing and distances of right-of-way tangents and other property lines.

Horizontal curve data for the right-of-way, including radius, delta and length.

Numbered bounds.

Slope, drainage and other easements and encumbrances.

Edge of pavement and driveway entrances.