SECTION 814 GUARDRAIL SYSTEMS
814.01 DESCRIPTION. This section covers material requirements for corrugated sheet
steel beams and accessories for guardrail, termin al sections, guardrail posts, offset blocks, end treatments, and timber guard posts.
814.02 BEAMS AND ACCESSORIES. Conform to AASHTO M 180. Hardware for
Type I, II, or III beams may be either hot-dip galvanized, electrogalvanized, or mechanically galvanized. Galvanize hardware according to AASHTO M 232. Galvanize beams according to AASHTO M 180. The Engineer will reject beams with zinc oxide (white rust) in amounts deemed objectionable. Furnish Ty pe II beams of either Class A, 0.105 inch thick or Class B, 0.135 inch thick as specified in the Contract.
814.03 TERMINAL SECTIONS. Conform to AASHTO M 180 and the details shown
on the Standard Drawings. Furnish Type 2 sect ions of either Class A, 0.105 inch thick or Class B, 0.135 inch thick as specified in the Contract.
814.04 GUARDRAIL POSTS. Provide either steel or timber, and use the same type
throughout the Project.
814.04.01 Steel Guardrail Posts. Fabricate from steel conforming to ASTM A 36 for
the wide flange shapes. Punch or drill holes for connector bolts before galvanizing. Galvanize all posts according to AASHTO M 111.
814.04.02 Timber Guardrail Posts. .Furnish either square sawn or round timber
guardrail posts. Conform to the nominal dime nsions shown on the Standard Drawings. The Engineer will allow a minus 2-inch tolerance from the specified nominal length. Saw the butts of all posts square, and finish th e tips as specified in the Contract. Bore bolt holes to a driving fit for the bolts. Frame, bore, and trim, as much as is practical, before giving the posts a preservative treatment. When it is necessary to bore or cut the posts after treatment, or when any treat ed surface has been badly scarred, treat the cut or scarred surface according to AWPA M4. Treat the posts with preservative according to AWPA U1, Section B, Paragraph 4.1 as applicable for guardrail posts. Use only one type throughout the project unless otherwise approved by the Engineer. Use any of the species of wood for round or square posts covered under AWPA U1. When furnishing oak posts, treat with creosote or creosote solution according to AWPA U1, Section B, Paragraph 4.1 for “Above Gr ound, Soil or Fresh Water Exposure.” See Subsection 818.01 for inspection, testing and acceptance procedures for Timber Guardrail Posts.
A.Square Sawed Posts. Ensure the posts, in the direction parallel to the axis of the bolt holes, do not exceed the dimensions specified in the Contract by more than 1/4 inch. Use posts that have straight grain, and that have a slope of the grain not deviating more than one inch in 12 inches from being parallel to any face when measured over the middle one-half of the length. The Engineer will not accept posts having a crook exceeding 1/2 inch in 10 feet. Limit wane to one end of the post only, and do not allow it to extend more than 10 feet from that end. Do not reduce the flat width of any face by more than 25 percent at the point of most wane. Do not use wood with ant tunnels, woodpecker holes, plugged holes, or any large unsightly gaps. The Department will allow wood with grub and worm holes less than 1/2 inch in average diameter, pr ovided that the sum of the diameters of all holes in any 12 inches of post length does not exceed 1/4 the nominal width of the face. Do not use posts showing signs of powder post beetle infestation. The 814-1 Engineer will not limit the use of posts that have grub holes appearing entirely on the surface of the post and that do not penetrate to more than 1/2 inch in maximum depth. Do not use posts with knots greater th an 3/8 the nominal width of the face, measured by the smallest diameter. Do not allow the sum of the diameters of all knots in any 6 inches of post length to exceed 3/4 the nominal width of the face. Do not allow the sum of the diameter of all knots appearing within the middle half of the length of any face to be greater than 4 times the size of the largest knot allowed in that face. The Department will allow posts with unsound knots no larger than half the maximum allowable size for sound knots and no more than 1 1/2 inches in depth, provided that the surrounding wood is not affected by the decay. Do not use posts that have clusters of knots where the maximum distortion of the grain around the cluster exceeds the maximum allowable size for one knot. Entirely confine shakes within the ends of the post, without extending to any face. Measure the shake as the sum of the 2 adjoining sides of the smallest rectangle that will completely enclose the shake. Measure the sides of the rectangle parallel to the faces of the post. Do not allow shakes to occur in more than one annual ring or to extend to more than 3/4 of the circumference of the annual ring in boxed heart. Do not allow total shake measurement to exceed one-half the width of the face. Do not use posts with splits greater in length than the width of the face. Do not use posts with a check or series of contiguous checks having a width of 8 mm or greater at the surface and more than 3 inches in depth at any point and extending more than 3/4 of the length of the post from one end. The Engineer will determine the depth of checks by the penetration of a probe 1/64 inch thick and 1/4 inch wide. The Engineer will consider the extent of a check or series of contiguous checks to end at the last point where the opening does not exceed 1/8 inch in width and is no more than 3/4 inch in depth. Do not use any post having a shake that does not exceed the maximum limits for shakes as specified herein, but contains a check which penetrates to the annual ring in which the shake occurs.
B.Round Posts. Peel all posts for their full length, and remove all outer and inner bark. Shave all knots and projections smooth and flush with the surface of the surrounding wood. Ensure that the posts are a constant diameter not less than 1/4 inch under the nominal diameter. Do not use posts that have short or reverse bends, one way sweeps exceeding one inch, and winding twists that are unsightly and exaggerated. The Engineer will not allow more than 10 percent of the number of pieces of any shipment to contain the maximum sweep. Do not use posts with unsound, loose or hollow knots. The Department will allow use posts that have sound knots when the diameter of any one knot or when the combined diameters of 2 or more knots occurring in the same cross section are no greater than 1/3 of the diameter of the post at that cross section. Ensure that posts are close grained and do not show spiral grain exceeding 1/8 turn in 5 feet. Do not use posts with seasoning checks that penetrate the interior of the post to a depth greater than 1/3 of the diameter at any point, or which measure more than 1/4 inch in width at any point. Do not use posts that have ring shakes, sap rot, bird pecks, insect holes, pitch pockets, or pitch streaks, and other defects that will impair the strength of the post, or give it an unsightly appearance.
814.05 OFFSET BLOCKS. Use the size, and when specified, the type the Contract
specifies.
814.05.01 Wood. Conform to 814.04 for material properties.
814-2
814.05.02 Composite Plastic. Select composite offset blocks conforming to this
section and assure blocks are from a manufact urer included on the Department's List of Approved Materials. Use blocks that are uniform in composition throughout the product and consist of at least 70 percent plastic by weight. Rubber is an acceptable alternative to plastic in their composition. Use sufficient additives to inhibit photo degradation. The Department will consider 2 percent carbon black to be a minimum. Ensure the blocks conform to the Manual for Assessing Safety Hardware (MASH) Test Level 3 requirements.
814.06 MATERIALS FOR END TREATMENTS. Conform to Subsections 814.02
through 814.05 for common components, and, except where otherwise provided, ensure they are of the same class and type as required for the guardrail to which they are attached. Galvanize all non-corrosion-resistant metals used in end treatments according to AASHTO M 111 or AASHTO M 232 as applicable. For proprietary end treatments, all materials shall conform to the manufacturer’s specifications. For other materials, comply with the following requirements:
A.Anchorage Systems. Furnish anchorage systems that have a minimum breaking strength of 40,000 pounds. The anchorage system may employ either a cable assembly or continuous steel rod or other system of eq ual or greater strength when approved. For cable assemblies, use cable that is 3/4-inch (6 by 19) wire rope conforming to AASHTO M 30, Class C. Provide swage fittings as required by the Standard Drawings and include studs as required. Ensure that eye bolts conform to ASTM A 489 and are of either Type 1 or Type 2. For wire rope clips use a commercial grade capable of being torqued to a minimum of 130 foot-pounds. Use commercial grade wire rope thimbles.
B.Anchor and Miscellaneous Plates. Fabricate from steel conforming to Subsection
812.01 01.
C.Miscellaneous Hardware. Bolts ASTM A 307 Nuts ASTM A 563, Grade A or better
D.Steel Sheet (for rail plates and mounting brackets). Conform to ASTM A 1011, Type SS, Grade 36
E.Tubular Sections (for posts and blocks). Conform to ASTM A 500, Grade B or ASTM A 501.
F.Concrete. Conform to Section 601, Class A.
G.Welded Wire Fabric. Use welded wire fabric for concrete reinforcement that is W3 by W3, 6 by 6-inch conforming to Subsection 811.04. The Department may allow other approved types of steel reinforcement. 814-3 SECTION 815 – GEOGRI D REINFORCEMENT
815.01 DESCRIPTION. This section describes geogrid physical requirements for
reinforcement of subgrad e and aggregate bases.
815.02 GENERAL. Furnish geogrid, formed by a punch and drawn method, composed of
polypropylene or high-density polyethylene resins.
815.03 PHYSICAL REQUIREMENTS. Furnish geogrid conforming to the Required
Geogrid Properties Table. Required Geogrid Properties1, 2, 3 Property Test Method Required Value English Metric Strength at 2% Strain ASTM D 6637 410 lb/ft 6.0 kN/m Strength at 5% Strain ASTM D 6637 810 lb/ft 11.8 kN/m Ultimate Tensile Strength ASTM D 6637 1310 lb/ft 19.2 kN/m Minimum Opening Size4 Direct Measure 0.5 in 12.7 mm Maximum Opening Size5 Direct Measure 3.0 in 76.2 mm Junction Strength GASTM 7737-11 93% Ultimate tensile strength Ultraviolet Stability AS TM D 4355 70% at 500 hrs Separation ASTM D 422 D15 of aggregate above geogrid < 5 x D85 subgrade and D50 of aggregate ≤ 25 x D50 of subgrade. Otherwise use a separation geotextile with geogrid NOTES:
1.Acceptance of geogrid material shall be based on ASTM D 4759.
2.Acceptance shall be based upon testing of either conformance sample obtained using Procedure A of ASTM D 4354, or based on manu facturer's certificat ions and testing of quality assurance sample obtained us ing Procedure B of ASTM D 4354.
3.Minimum use value in weaker principal di rection. All numerical values represent minimum average roll value (i.e., test results from any sampled roll in a lot shall meet or exceed the minimum values in the table). Lot samples according to ASTM D 4354.
4.Minimum opening size must be ≥ D50 of aggregate above geogrid to provide interlock.
5.Maximum opening size must be ≤ 2 x D85 of aggregate above geogrid to prevent aggregate from penetrating into the subgrade 815-1
Source: Kentucky Standard Specifications for Road and Bridge Construction, 2019 Edition. Pages 598–600 of 718.