Chapter 12.05
ROAD STANDARDS FOR DEVELOPMENTS
Sections:
12.05.030 General requirements.
12.05.010 Purpose.
The purposes of this chapter are:
A. To promote the orderly development of Columbia County by providing uniform standards for the planning, design and construction of roads and streets for subdivisions, short plats and planned area developments.
B. To protect and facilitate landowner and developer investments by ensuring the availability and reliability of adopted standards when preparing plans and cost estimates prior to submitting an application for county approval.
C. To ensure consistency in the governmental approval process and thereby preventing or avoiding special or conflicting interests. [Ord. 87-02 § 1.]
12.05.020 Definitions.
In addition to those applicable definitions contained in the Columbia County zoning and subdivision ordinances (CCC Titles 17 and 18), the following definitions shall apply:
“AASHTO” means the American Association of State Highway and Transportation Officials.
“Dedication” means the assignment of property by the developer, either as fee title or as an easement right, for specific public use and its acceptance for such use by the appropriate governmental agency.
“Development” refers to either a subdivision, short plat or planned area development, as used herein.
“Driveway” means a private roadway serving only one lot providing reasonable access to a homesite.
“Easement” means an interest in land created by grant or agreement which confers a right upon the owners of the easement, either private or public, to some profit, benefit, dominion, or lawful use of the estate of another.
Paved Surface. The minimum standard considered a paved surface is bituminous surface treatment, Class A, as defined by the Washington State Department of Transportation Standard Specifications. Dust abatement treatment shall not be considered as bituminous surface treatment.
“Private road” means a nondedicated road not designed, built, or maintained by Columbia County, the Washington State Department of Transportation, or any political subdivision of the state.
“Right-of-way width” means the area designated on the plat or other documents for any current or future use as a roadway, for use in placement of utilities, accessory services and any other pertinent usages.
“Rural road standards” means road design standards for developments that are outside the urbanizing area of the city of Dayton, with unforeseen annexation or hookup to city water/sewer facilities.
“Urban road standards” means road design standards for developments that are adjacent to or within the urbanizing area of the city of Dayton which provides or is expected to provide urban services. [Ord. 87-02 § 2.]
12.05.030 General requirements.
A. Dedicated Roads. All roads dedicated to the public shall meet the minimum standards for major roads within rural or urban areas. Additional right-of-way may be required for major arterials or for roads that may be determined by the county as potential major arterials or in areas of extreme topography.
B. Private Roads. The following shall be applicable to all private roads in developments:
1. The owners and successors-in-interest in any development which contains or is served by a private road shall, as a condition of plat approval, agree to share in the cost of a road improvement in the event the county should accept the road to the county road system at a future date.
2. The face of any plat containing a private road shall bear the following language:
“WARNING” Columbia County has no responsibility to build, improve, maintain, or otherwise service the private roads contained within or providing service to the property described in this plat.
3. A sign shall be erected at the intersection of the private road and the county road or other public way which contains the message “PRIVATE ROAD” with four-inch reflectorized letters on a green background.
4. Private road right-of-way corridors shall be located and designed according to the following basic guidelines:
a. Four or less lots: 20 miles per hour;
b. Five or more lots: 35 miles per hour.
The county engineer shall verify the location and design adequacy in accordance with the above guidelines.
5. Developments which include private roads serving five or more lots shall be supported with a plan and continuing resources for maintenance of the private roads to a level consistent with the standard of construction. This support may be in the form of plat covenants, binding agreement, landowner associations, special maintenance district, a combination thereof, or other support, all subject to approval of the final plat by the county.
C. Continuation of Roads. Development road design and right-of-way location shall provide for the continuation of roads, either dedicated or private, which may serve contiguous property deemed by the county to be capable of future subdivision.
D. Road Access Permits. New roads connecting to existing public roads shall not be approved in subdivisions, short plats or planned area developments unless a permit is acquired from the appropriate agency with jurisdiction.
E. Traffic Control Signs. All roads dedicated to the public shall be signed in accordance with the provisions of the Manual for Uniform Traffic Control Devices adopted by the state of Washington.
F. Aesthetic Considerations. Consideration shall be given to preservation of natural features in the design and layout of roads in a subdivision, short plat or planned area development.
G. Existing Roads. Existing roads abutting a proposed subdivision will be considered as part of the subdivision and may be required to be developed to county standards as a condition of approval. [Ord. 87-02 § 3.]
12.05.040 Design standards.1
A. Private Roads. Private roads in the urban and rural areas shall comply with the following minimum standards. (Private driveways are excluded from these provisions.)
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Minimum curve radius: |
150 ft. |
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Maximum sight distance: |
150 ft. |
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Maximum grade: |
12% (see exceptions in subsection (A)(1) of this section) |
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Roadway Surface Type |
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Urban area |
Paved surface on a 6-inch depth of crushed aggregate base |
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Rural area |
Gravel surface on a 4-inch depth of crushed aggregate with 1-1/4-inch maximum particle size |
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Minimum Roadway Width (Shoulder to Shoulder) |
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4 or less lots: |
20 ft. (see exception in subsection (A)(1) of this section) |
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5 or more lots: |
20 ft. |
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Minimum right-of-way width: |
60 ft. (see exception in subsection (A)(1) of this section) |
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Vertical clearance: |
14 ft. |
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Drainage Structures |
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Hydraulic capacity: |
10-yr. flood freq. |
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Structural capacity: |
H15 (AASHTO) |
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Bridges |
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Roadway width: |
20 ft. |
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Structural capacity: |
H15 (AASHTO) |
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Design hyd. capacity: |
50-yr. flood freq. |
1. Exceptions to the above standards which may be considered are:
a. In the event the subdivider can show adequate evidence that a grade of 12 percent or less may cause unnecessary hardship, a grade greater than 12 percent may be permitted.
b. In a roadway width serving four lots or less, and in the event the subdivider can show adequate evidence of an undue hardship, the county may consider a minimum of 12-foot roadway width with turnouts, such turnouts to be located not more than 400 feet apart and not less than 40 feet in length and not less than 10 feet in width.
c. In a right-of-way width serving four lots or less and in the event that the subdivider can show adequate evidence that the 60-foot right-of-way will cause undue hardship, the county may consider a minimum 40-foot right-of-way width; providing further, that the subdivider shall furnish adequate evidence that no further subdivision or extension may occur within the 40-foot right-of-way area.
2. All exceptions shall meet the following provisions:
a. The hardship which serves as a basis for granting exceptions is specifically related to the property of the applicant and not to the area in general; and
b. Any exception granted will not be contrary to the public interest, health, and general welfare; and
c. The intent and spirit of the Columbia County road standards and Columbia County’s subdivision ordinances (CCC Title 17) are observed and substantial justice done; and
d. The granting of such exception from Columbia County road standards will not constitute a grant of special privilege; and
e. The county engineer and the county planning commission shall recommend approval and be subject to other county platting requirements.
B. Planned Area Development Private Roads. In addition to the minimum standards specified in subsection (A) of this section, private roads in concentrated “cluster” or “condominium” type planned area developments shall comply with the following:
1. Minimum roadway width, one-way traffic: 14 feet.
2. Minimum roadway width, two-way traffic: 20 feet.
3. Off-street parking bays required: two spaces per dwelling unit.
C. Urban Roads. Dedicated roads within the urban area shall be constructed in accordance with the current county minimum design standards for urban streets and roads unless a higher standard is required to be consistent with city street standards.
D. Rural Roads. Dedicated roads in rural areas shall be constructed in accordance with the current county minimum design standards for rural roads and streets. In all cases the design and construction of roads and streets, which are or may be dedicated to the county, shall be closely coordinated with the Columbia County engineer to ensure compliance with these standards.
E. Road Structural Design. Structural design of all dedicated roads and streets within developments shall be based upon the volume and character of traffic, foundation soils characteristics, weather factors, performance of adjacent roadways, availability of local materials, and other considerations. Design procedures shall conform to accepted engineering practices approved by a registered professional engineer.
F. Intersections. Road intersections shall be as nearly at right angles as is practicable, but shall not be less than 60 degrees.
G. Cul-de-Sacs. A cul-de-sac turnaround shall be provided for all dead-end roads, serving four or more lots, with a minimum circular right-of-way radius of 50 feet.
H. Construction. All roads which are to become appurtenant to the completed development, as shown on the approved preliminary plat, shall be constructed in accordance with these standards prior to approval of the final plat. A performance bond or other approved surety in the amount of the estimated construction cost may be substituted in lieu of actual construction. Failure to complete construction in accordance with these standards prior to the first sale, lease or other transfer of any lot within the subdivision shall be cause for transfer of responsibility for performance of construction from the developer to his surety; provided, in the event the developer does not complete the development and no lots have been sold, leased or otherwise transferred, the plat may be vacated and the performance bond or other surety may be released.
I. Modifications. Modifications may be made to these minimum standards by the board of commissioners in cases of severe topographical or geologic conditions, aesthetic considerations or other conditions and considerations deemed appropriate and reasonable and when such modifications are deemed to provide a level of accessibility, traffic circulation, and safety equivalent to these standards.
J. If federal or state laws should require standards exceeding those specified herein, those federal or state laws or regulations shall prevail. [Ord. 87-02 § 4.]
References: Washington State County Arterial Design Standards; Washington State Local Agency Guidelines; WSDOT Standard Specifications for Road and Bridge Construction.