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(A) The Division of Highways shall review all drainage prior to acceptance of any facility to the state system. Drainage, utility or public easements, are not considered a portion of the highway facility.
(B) All storm drainage shall be adequate so that the road may be maintained without excessive cost and not cause flooding on private property from storm runoff of the design frequency. Permanent drainage easements may be established by the designer; however, the NCDOT does not accept maintenance responsibility for the easement outside of the roadway right-of-way. The minimum design frequency shall be as follows but may be increased at the recommendation of the State Hydraulics Engineer.
Cross drainage for secondary routes | 25 years |
Cross drainage on primary and N.C. routes | 50 years |
Minimum cross pipe diameter | 18" |
Minimum driveway pipes diameter | 15" |
Storm sewer collector | 10 years |
All drainage shall be consistent with criteria found in NCDOT's Guidelines for Drainage Studies and Hydraulic Design. (Contact Special Services Section (919) 250-4128.) |
(C) In areas where ditch grades or quantities of flow deem it impracticable to establish and maintain vegetation, an erosive resistant lining such as paving, matting or rip rap may be required.
(D) Subsurface drainage shall be adequate to maintain a stable subgrade.
(E) When road crossings are within areas designated as flood hazard areas under the Federal Flood Insurance Program, the design must be approved by the responsible local governing agency for its consistency with local flood zoning ordinances. Retention/detention basin shall be located outside the right-of-way and shown on plans where possible. The DOT assumes no responsibility for maintenance nor liability of the basins.
(Ord. passed 1-1-2000)
(A) Bridges. Minimum criteria for bridges to be built by private interest for future acceptance by the Division of Highways.
(1) Structures which are to span streams shall be designed for hydraulic requirements in accordance with Division of Highways criteria and plans shall be submitted to the Hydraulics Unit for review and approval. Rip rap will be required as recommended by the Hydraulics Unit.
(2) Structures shall be designed for minimum live load of HS-20 as specified in the Standard Specifications for Highway and Bridges of the American Association of State Highway and Transportation Officials, and plans shall be submitted for review and approval by the Structure Design Unit.
(3) Bridge deck widths and clearances shall be in accordance with the State Department of Transportation "Bridge Policy". For bridges with curb and gutter approaches, the clear bridge width shall be the same as the curb to curb approach width, except where bikeways or sidewalks are carried across the structure. Curb and gutter will be transitioned out in 50 feet to line up the face of curb and bridge rail. For shoulder section roadways, the bridge width should be a minimum of 24 feet.
(4) The following materials are acceptable for bridge construction:
(a) For substructures: reinforced concrete, structural steel, pre-stressed concrete, or steel piles or combination of these materials;
(b) For superstructures: pre-stressed concrete, reinforced concrete deck slab structural steel I-beams with reinforced concrete deck or corrugated metal deck with asphaltic wearing surface; and
(c) The type and design of bridge rails shall be as approved by the Structure Design Unit of the Division of Highways.
(5) Guardrails shall be installed at the bridge approaches where required.
(6) All material and workmanship used in construction of the structure shall be in accordance with State Standard Specifications for Roads and Structures.
(B) Roadway dams.
(1) It is the policy of the Division of Highways to discourage the location of roadways on dams. In those cases, where a definite advantage may be gained or a substantial savings in funds may be realized, the utilization of a dam for a roadway may be favorably considered.
(2) Where it is determined that a dam will be utilized as a roadway, the following criteria must be met.
(a) When applicable, the dam must have certification from the State Department of Natural Resources and Community Development pursuant to the "Dam Safety Law of 1967", (as amended by the General Assembly of 1977) being G.S. §§ 143-215.23 et seq.
(b) All pertinent data regarding the design of the embankment as an impoundment structure must be presented to the Division of Highways for review.
(c) The top cross section dimension must be the roadway width required (from shoulder point to shoulder point) for the facility plus a minimum of four feet.
(d) Guardrails will be provided on the impoundment side of the roadway. For safety, the District Engineer may require guardrail on both sides of the roadway.
(e) Spillways will be designed to provide two feet of freeboard at the shoulder for an estimated 50-year design frequency outflow as a minimum.
(f) A means of draining the lake completely will be provided.
(3) Design acceptance or approval by the Division of Highways is limited to the use of the dam as a roadway and is, in no way, intended as approval of the embankment as an impoundment structure.
(4) Responsibility incurred by the Division of Highways when a section of roadway crossing a dam is accepted as a part of the state maintenance system is limited to maintenance of the roadway for highway purposes from shoulder point to shoulder point only. Responsibility for the impoundment, any damage that may result therefrom, and maintenance of the dam or appurtenances as may be required to preserve its integrity as a water impoundment structure, shall remain with the owner of the impoundment. Any maintenance work will be subject to the provisions of G.S. § 136-93.
(5) Impoundment of water on highway right-of-way may be allowed under the following criteria:
(a) The impoundment does not adversely affect the right-of-way for highway purpose; and/or
(b) Adjustment, as required, flattening slopes, installing rip rap, and any others, shall be the responsibility of the developer.
(6) Structures under, over and/or on dams shall be designed and plans prepared under the supervision of a licensed professional engineer.
(Ord. passed 1-1-2000)
(A) All curb and gutter and sidewalk sections shall meet Division of Highways standards.
(B) The standard two-inch to six-inch concrete curb and gutter is the preferred type to be used.
(C) The concrete valley gutter is an allowable type.
(D) Any other types of curb and gutter shall be subject to the approval of the District Engineer.
(E) Curb inlet spacing and storm system design shall be consistent with criteria found in NCDOT's Guidelines for Drainage Studies and Hydraulic Design. (Contact Special Services Section (919) 250-4128.)
(F) NCDOT will allow sidewalks by encroachment and will not accept responsibility for maintenance. All sidewalks shall meet requirements of the Americans with Disabilities Act being 42 U.S.C. §§ 12101 et seq.
(Ord. passed 1-1-2000)
(A) In accordance with G.S. § 136-44.14, all street curbs in the state being constructed or reconstructed for maintenance procedures, traffic operations, repairs, correction of utilities or altered for any reason after 9-1-1973, shall provide wheel chair ramps for the physically disabled at all intersections where curb and gutter is provided and at other major points of pedestrian flow.
(B) Wheel chair ramps and depressed curbs shall be constructed in accordance with details contained in the Department of Transportation, Division of Highways' publication entitled, Guidelines, Curb Cuts and Ramps for Handicapped Persons.
(Ord. passed 1-1-2000)
(A) Shown below are minimum thicknesses of base and surface course to be used. Design should be chosen from Group I or Group II depending on subgrade soil type. The District Engineer may require a subgrade soil test to determine the soil classification type. Heavier pavement designs may be required based on traffic, truck volumes and the like.
Group I | ||
Good to Excellent Subgrade Soil Types | Base Course | Pavement Surface |
Group I | ||
Good to Excellent Subgrade Soil Types | Base Course | Pavement Surface |
A-l-a, A-l-b, A-3 | 7" STBC, Type A or C | 2" I-1 or I-2 |
A-2-4, A-2-5, A-2-6, A-2-7 | 9" STBC, Type A or C | 1-1/2" I-1 or I-2 |
8" ABC or STBC, Type B | AST, 1" SA or I-1 or I-2 | |
6" ABC or STBC, Type B | 1-1/2" I-1 or I-2 | |
3" ACBC, Type HB | 1-1/2" I-1 or I-2 | |
3-1/2" ACBC, Type HB | 1" SA or I-1 or I-2 | |
4" ACBC | 5" jointed concrete | |
Group II | ||
Poor to Fair Subgrade Soil Types | Base Course | Pavement Surface |
Group II | ||
Poor to Fair Subgrade Soil Types | Base Course | Pavement Surface |
A4, A-5, A-6, A-7-5, A-7-6 | 9" STBC, Type A or C | 2" I-1 or I-2 |
8" ABC or STBC, Type B | 1-1/2" I-1 or I-2 | |
10" ABC or STBC, Type B | AST, 1" S A or I-1 or I-2 | |
4" ACBC, Type HB | 1-1/2" I-1 or I-2 | |
3" ACBC, Type HB | 2" I-1 or I-2 | |
4" ABC | 6" jointed concrete | |
(B) Any other pavement design must be reviewed by the Division Engineer on an individual basis and approval will be based upon sound engineering principles. Decorative pavers may be permitted by encroachment. Maintenance of decorative pavers will not be performed by NCDOT.
(C) Note:
(1) Subgrade: no base course shall be placed on muck, pipe clay, organic matter or other unsuitable material;
(2) ABC aggregate base course, No. 7 stone;
(3) STBC soil type base course;
(4) AST asphalt surface treatment;
(5) SA asphalt concrete surface course, Type F-l (sand asphalt);
(6) I-2 asphalt concrete surface course, Type I-2;
(7) I-1 asphalt concrete surface course, Type I-1;
(8) ACBC asphalt concrete base course, Type HB (black base); and
(9) Other base courses such as various cement-treated materials may be used in lieu of those shown above. These materials shall be of sufficient thickness to provide equivalent strength. However, any design other than those shown above must also be approved prior to use by the Division Engineer.
(D) All materials shall meet the requirements set forth in the latest edition of the state's Standard Specifications for Roads and Structures.
(Ord. passed 1-1-2000)
The construction of all subdivision road intersections including those with existing state maintained roadways shall be constructed using traffic control standards as designated in the Manuals on Uniform Traffic Control Devices, state supplement to the Manual on Uniform Traffic Control Devices and the North Carolina Highway Design Branch Roadway Standard Drawings, prior to formal addition to the system. See G.S. § 136-30.
(Ord. passed 1-1-2000)
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