It is the purpose of this manual to provide consistent standards for construction of new private roads built in Bonner County and reconstruction or renovation of existing private roads for subdivisions, in Bonner County. All construction shall conform to the standards set forth in this manual.

   A.   The Board of County Commissioners is authorized to waive requirements of appendix A upon satisfaction of the criteria of this section. The purpose of granting a waiver under the provisions of these regulations shall be to ensure that an applicant is not unduly burdened as opposed to merely inconvenienced by the Private Road Standards. The Board shall not approve any waiver(s) except finding that all of the following apply:

      1.   The granting of the waiver will not result in impacts that are detrimental to the public safety, health or welfare or injurious to other property.

      2.   Granting the waiver shall substantially secure the objectives, standards and requirements of these regulations.

      3.   A practical hardship, or unnecessary and unreasonable expense, would result from strict compliance with the foregoing regulations.

      4.   The purpose of these Private Road Standards may be served to a greater extent by an alternative proposal, or where such requirements are redundant and clearly unnecessary for the land division in a particular area. (Ord. 581, 10-24-2018)

Definitions

APPROACH: As used in this manual, the term "approach" shall mean any vehicular entrance upon a County right-of-way, other than driveway.

COUNTY: The term "County" refers in all instances to Bonner County, Idaho.

DRIVEWAY: As used in this manual, the term "driveway" shall mean a vehicular entrance upon a right-of-way/easement or a roadway which provides access to a fourplex or smaller multi-family dwelling or two (2) or fewer single-family residential lots or parcels.

LOCAL FIRE AGENCY: The fire district, fire subscription agency or Bonner County in the absence of a fire district or subscription area.

NEW ROAD: As used in this manual, the term "new road" shall mean any road built as a private road or existing private road(s) renovated or reconstructed for subdivisions and not defined as a "driveway".

PRIVATE ROAD: Is that road which is to be constructed, reconstructed or renovated within an easement or private right-of-way.

PROJECT ENGINEER: As used in this manual, the term "project engineer" shall mean a registered professional engineer, licensed in the State of Idaho, and who is retained to design, construct or supervise the construction of a new or renovated or reconstructed road.

ROAD SURFACE, ROADWAY: As used in this manual, the terms "road surface" and "roadway" shall mean the travelway and the road shoulders on each side.

TRAVELWAY: That portion of a road which has been improved for the movement of vehicles, exclusive of shoulders.

   1.1 Applicability

The standards contained within this manual shall be applicable to construction of new private roads built in Bonner County or existing roads renovated or reconstructed for subdivisions in Bonner County and not defined as a "driveway".

   2.1 General Requirements

Construction of new private roads built in Bonner County and existing private roads renovated or reconstructed for subdivisions in Bonner County shall conform to the standards set forth in this section. Note: Dedication of easement (right of way) to homeowner association shall be provided as part of final plat/deeds of family exemption and may be included in the gross acreage, where authorized by this title.

A road maintenance agreement shall be provided with the subdivision application.

   2.2 Design And Layout

   A.   New roads shall be laid out and designed in conformance with the transportation portion of the comprehensive plan.

   B.   New roads serving residential subdivisions shall be designed to connect to local access roads or collectors. New roads shall be designed to provide access to each lot.

   2.3 Specifications For Drawings

   A.   The project engineer shall prepare road and right of way/easement drawings, and each sheet of the drawings shall bear the seal of such engineer. A licensed surveyor may prepare the right of way/easement drawings, and each sheet of the drawings shall bear the seal of such surveyor.

   B.   Two (2) copies of the design drawings shall be submitted to the Bonner County planning department. The planning department shall provide one copy to the local fire agency official. All drawings shall include the following, when applicable:

      1.   The first sheet of the plans shall include a project title, vicinity map, and index of plan sheets.

      2.   Road horizontal and vertical alignments with fifty foot (50') stationing, reading from left to right, and stationing at point of curve, tangent and intersections, with appropriate ties to existing road surveys and stationing, section corners, quarter corners, and the horizontal control established by the engineer and/or project surveyor. Stations shall increase from west to east and from south to north.

      3.   Section, township and range.

      4.   Bearings on the road centerline, keyed to an associated plat map.

      5.   Curve data including radius, delta, arc length, and semitangent length, on all road centerlines and curb returns.

      6.   Right of way/easement lines, width for proposed road travelway and roadway, intersecting roads, and existing road improvements with dimensions.

      7.   All topographic features within right of way/easement limits or future right of way/easement limits and sufficient area beyond to resolve questions of setback, cut and fill slope, drainage, access onto abutting property, and road continuations.

      8.   All existing utilities.

      9.   All proposed water and sewer utilities that will be designed and constructed.

      10.   Identification of all roads and adjoining subdivisions.

      11.   Existing and proposed drainage features, showing direction of flow, size and kind of each drainage channel, pipe, and structure and other specified requirements in any county stormwater management specifications.

      12.   Horizontal scale: One inch equals fifty feet (1"=50') and a vertical scale of one inch equals ten feet (1"=10'). However, one inch equals one hundred feet (1"=100') shall be optional for development of lots one acre or larger. Details for clarification may be shown on a convenient scale. A scale of one inch equals twenty feet (1" =20') may be required for urban arterial streets where detail is sufficiently dense to cause a "cluttered" drawing at a smaller scale.

      13.   A north arrow.

      14.   Project beginning and ending designation with stations.

      15.   A title block to include:

         a.   The project name;

         b.   Sheet number;

         c.   Road names;

         d.   Road limits.

      16.   All found and referenced survey monuments.

      17.   Section and lot lines.

      18.   Beginning, middle and ending elevations of curb returns.

Other data necessary for the specific project.

   2.4 Width Of Right Of Way/Easement Required

   A.   New private roads shall have a minimum right of way/easement width that shall be of sufficient width to accommodate all cuts and fills, snow storage and stormwater features, but not less than thirty feet (30') in width.

   B.   Effort shall be made to provide through roads within a subdivision and minimize the need for dead ends. Cul-de-sacs and hammerhead turnarounds shall have a right of way/easement sufficient to provide area within the right of way/easement for storage of snow removed from the roadway.

   C.   Cul de sacs/hammerhead turnarounds shall be designed and constructed in accordance with the current edition of the international fire code, as adopted by the state fire marshal, and such later editions as may be so published and adopted by the state fire marshal, or as amended, modified or superseded, and incorporated herein by reference with a copy on file with the office of the clerk of the board of county commissioners, and hereinafter referred to as IFC.

   2.5 Road Design

   A.   The minimum and maximum for design parameters of new roads shall be:

 

 

* Variation to grades steeper than 10 percent may be approved by Bonner County through the subdivision process where evidence is provided by the applicant that steeper grades are necessary and can accommodate fire and emergency vehicles.

** Variations to roadway widths to allow a minimum of 14 feet may be approved by Bonner County through the subdivision process where evidence is provided by the applicant that the required roadway width cannot be installed because of topography, waterways or other similar restricting conditions and that the narrower width will not obstruct access by fire and emergency vehicles. When a width variance is approved, a turnout on each end of the reduced width section shall be constructed to a minimum of 26 feet in overall travelway width and 40 feet in length, with the turnouts constructed on the right as the traffic enters the reduced width section. No driveways or other access roads shall be allowed in the roadway width varied area.

The request for variation shall include evidence provided by the project engineer in regards to safety, maintenance and year round access.

For the purposes of the standards contained in this manual, private roads are further divided into three (3) subcategories as shown below. Where the term private road is used within the text, it shall include all of the following subcategories:

      1.   High Density Private Road: A private access road, in any area zoned for lot or parcel sizes of twelve thousand (12,000) square feet or less in size on the official Bonner County zoning map.

      2.   Standard Private Road: A private access road with a projected traffic volume* of two hundred (200) or more vehicle trips per day, or in an area zoned for lot or parcel sizes greater than twelve thousand (12,000) square feet and less than five (5) acres in size on the official Bonner County zoning map.

      3.   Low Volume Private Road: A private access road with a projected traffic volume* of less than two hundred (200) vehicle trips per day, and in an area zoned for lot or parcel sizes of five (5) acres or greater on the official Bonner County zoning map. Note: Private roads are not maintained by Bonner County.

* Projected traffic volumes to be based on ten (10) vehicle trips per day per household over the design life of the road (usually 20 years).

New private roads shall have a minimum roadway width, travelway width and surfacing based on the classification of the road as follows:

 

 

Hard surfaced roads shall have a minimum surfacing of a two (2) shot application of light bituminous surface treatment.

   B.   Where fire hydrants are located along the roadway, the minimum width of the travelway shall be twenty six feet (26'). This may be accomplished by construction of a turnout providing an overall travelway width of twenty six feet (26') and forty feet (40') in length at the hydrant location.

   2.6 Road Intersections

All new private roads which intersect new or existing roads and rights of way/easements shall intersect at an angle which is between eighty (80) and one hundred degrees (100o), and as close to ninety degrees (90o) as is possible. The edge of the road surfaces shall be connected with a curve having a minimum radius of twenty eight feet (28'). All new roads intersecting a public right of way shall be constructed or reconstructed to meet the current Bonner County road standards.

   2.7 Visibility At Intersections

At intersections, a minimum clear sight triangle shall be maintained as illustrated on plate 2, sight triangle at intersections, of the current Bonner County road standards manual. It shall be the responsibility of the developer/adjacent landowner to maintain the clear sight triangle at all times.

   3.1 Clearing And Grubbing

Prior to the start of road construction, clearing of the entire width of the right of way/easement shall be completed. All materials removed by clearing or grubbing shall be properly disposed of in compliance with state and local requirements. All denuded areas shall be erosion protected as specified in the stormwater and erosion control plan if applicable.

   3.2 Erosion Control

During road construction, erosion control measures shall be installed and maintained to minimize soil erosion from disturbed sites. Permanent erosion control measures shall be included in all road designs, with design guidance from the handbook of best management practices for stormwater management and erosion and the Idaho standards for public works construction. Refer to title 12, subchapter 7.2 of the Bonner County Revised Code for stormwater management and erosion control plan requirements.

   3.3 Subgrade

   A.   The subgrade shall consist of the native materials remaining after duff (organic material) and topsoil have been removed and suitable underlying road construction material, or to a depth as necessary to allow placement of sufficient depth of subbase material. The extent of the excavation necessary to expose the subgrade shall be determined by the project engineer. Soil and compaction tests are required to document the acceptability for construction. All testing shall be at the expense of the developer.

   B.   In solid rock excavation, the solid rock shall be excavated six inches (6") below the finished subgrade elevation and backfilled with approved granular material.

   C.   Unstable subgrade conditions shall be remedied by over excavation and backfilling with approved material under the direction of the project engineer and/or placement of appropriate geosynthetic materials to meet the required vehicular support criteria.

   D.   Subgrade shall be prepared as necessary to allow overlying road material to be constructed in accordance with these specifications.

   E.   Prior to placing any ballast on the subgrade, the project engineer is responsible for ensuring that all testing, required inspections and standards outlined herein are adhered to.

   3.4 Ballast

   A.   All underground utilities and conduits crossing the road shall be installed before placement of ballast material.

   B.   Pit run gravel or fractured rock I shall be used for the ballast material. Ballast material shall have a sand equivalent of not less than thirty (30), and which meets the following gradations:

 

 

   C.   The ballast material shall be placed in loose six inch (6") to nine inch (9") lifts and shall be compacted using mechanical methods to at least ninety five percent (95%) of the ASTM D-698 standard proctor density.

   D.   Prior to placing any top course material on the ballast, the project engineer is responsible for ensuring that all testing, required inspections and standards outlined herein are adhered to.

   E.   All culvert installations crossing the roadway shall be installed before any base material is placed.

   F.   Recommended ballast thickness and top course thickness:

The following charts may be used by the project engineer to assist in the soils classification and to determine the depth of the minimum required ballast and top course material. The intent is to design a roadway section capable of providing an all-weather road for a seventy eight thousand (78,000) pound fire apparatus.

   SOILS DESCRIPTIONS/DEFINITIONS

 

** GM and GC soils are highly dependent on the % silt or clay, a 35 r value is on the conservative side.

Subgrade R value may require the minimum road section design to be increased under the direction of the project engineer.

   3.5 Top Course

   A.   Top course material shall meet the following gradation requirements:

 

 

   B.   At least sixty percent (60%) of the crushed aggregate particles retained on the no. 4 sieve shall have at least one fractured face.

   C.   The Los Angeles abrasion test may be required to ensure the top course aggregate does not show more than a loss of thirty five percent (35%) and the sand equivalent not less than thirty (30).

   D.   The material shall be placed in loose lifts not to exceed six inches (6") in depth and compacted to the approved design depth. The material shall be mechanically compacted by rolling to ninety five percent (95%) of the ASTM D-698 proctor density. The aggregate shall be placed in such a manner that it will have a uniform mixture throughout.

   E.   Prior to placing top course material on the ballast, the project engineer is responsible for ensuring that all testing, required inspections and standards outlined herein are adhered to.

   3.6 Road Signage

   A.   Road Name: No new private road or existing renovated or reconstructed private roads shall be considered completed until a road name sign has been installed. It shall be the responsibility of the developer/landowner to purchase, erect and maintain the road name signs. All road name signs shall conform to the standards contained in the latest edition of the manual on uniform traffic control devices and Bonner County Revised Code.

   B.   Stop Sign: A stop sign shall be installed at the intersection with all public roads. Stop sign dimensions, installation and location shall conform to the latest edition of the MUTCD. It shall be the responsibility of the developer/landowner to purchase, erect and maintain the stop signs.

   3.7 Standards For New Bridge Construction

The standard for bridge design within private roads shall at a minimum be HB-16-1996, as described in the AASHTO standard specification for highway bridges, 16th edition.

   3.8 Engineering Requirements

Inspections Required:

The project engineer shall, at a minimum, conduct on site inspections of the new private road construction at the following stages of construction:

   A.   Completion of any construction surveying and staking.

   B.   Completion of subgrade, prior to the placement of any ballast material.

   C.   Completion of ballast, prior to the placement of any top course material.

   D.   Completion of installation of road signs, installation of any appurtenant structures, and reseeding of disturbed area and slopes.

   3.9 Final Report And As Built Drawings

At the completion of the road construction, and following the last required inspection, the project engineer shall submit two (2) copies of the final report and as built drawings for the new road and any appurtenant structures to the planning department. The planning department shall provide one copy to the local fire agency official. The final report shall include complete information related to the road construction and at a minimum, include the following information:

   A.   Dates of inspection, work performed and inspected, changes or repairs ordered.

   B.   Weather conditions, unusual or unexpected site conditions.

   C.   Engineering operations performed.

   D.   The appropriate inspection and information checklist.

   REQUIRED INSPECTION & INFORMATION CHECKLIST

Check off when completed & submit to Bonner County Planning Department

PROJECT NAME:                                                   

For all private roads:

      Project engineer shall submit construction inspection notes

      Verify the section depth

      Submit nuclear density gauge field data sheets

      Submit subgrade density test results

      Density tests are required for every lift at a minimum frequency of 300 linear feet, for all materials, special attention shall be paid to curve returns, cul-de-sacs/hammerhead turnarounds or sensitive areas

      (Other requirements-verified by engineer)

CERTIFICATION OF COMPLETION/ACCEPTANCE:

I CERTIFY THE PROJECT IS COMPLETED IN GENERAL ACCORDANCE WITH THE APPROVED PLANS AND SPECIFICATIONS.

Project Engineer Signature    Date

Project Engineer Name Printed

(Ord. 501, 11-18-2008)