§ 155.039 PAVEMENT DESIGNS.

   (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
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
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)