Section 724 — Guardrail

724.01Rail Elements.

(a)Metal beam rail. Provide metal beam rail conforming to Task Force 13 (TF13), Guide to Standardized Roadside Hardware .

(1)Galvanized steel. Provide W -beam or thrie -beam rail fabricated from corrugated sheet steel conforming to AASHTO M 180 for the designated shape, type, class, and mass of coating specified.

(2)Painted steel. Provide W -beam or thrie -beam rail conforming to AASHTO M 180 for the designated shape, class, type, and mass of coating specified.

(3)Corrosion resistant (weathering) steel. Provide W -beam or thrie -beam rai l conforming to AASHTO M 180, Type IV, Class B.

(b)Box beam rail. Provide steel box beam rail conforming to TF13, Guide to Standardized Roadside Hardware .

(c)Steel -backed timber rail and rub rail. Provide timber conforming to AASHTO M 168. Fabricate the timber r ail and rub rail from dry, seasoned, and dressed rough sawn southern pine or other species having a stress grade of at least 1500 pounds per square inch. Do not use refractory species (such as larch or Rocky Mountain Douglas fir). Provide treated timber conforming to AASHTO M 133. Provide steel backing elements according to ASTM A242. (d) Steel -backed log rail. Provide No. 1 Grade western hemlock, western red cedar, or pine logs that are seasoned, straight, and sound. Do not use logs that taper more than 2 inch es between the butt and tip ends of adjacent logs. Remove bark and at least 80 percent of the inner bark. Do not use logs with peeler or incision marks on surfaces that will be visible. Do not use logs with knot clusters. Logs may contain sound, tight, wel l-spaced knots. Do not use logs with season checks, singular or any two opposite each other, that exceed the thickness of the member. Provide treated timber conforming to AASHTO M 133. Provide steel backing elements according to ASTM A242.

724.02Guardrail Posts. Provide guardrail posts conforming to TF13, Guide to Standardized Roadside Hardware .

(a)Wood. Provide posts that do not have a through check, shake, or end slit in the same plane as, or a plane parallel to the bolt hole and extending from the top of the post to within 3 inches or the bolt hole. Provide according to AASHTO M 168 and treat according to AASHTO M 133. For steel -backed timber guardrail systems, provide posts conforming to Subsection 724.01(c) . For steel -backed log rail systems, provide posts conforming to Subsection 724.01(d) .

(b)Steel. Provide posts of the appropriate size shape according to ASTM A6. Zinc -coat the embedded portion of corrosion resistant (weathering) steel posts according to ASTM A123.

724.03Guardrail Blockouts. Provide guardrail blockouts conforming to TF13, Guide to Standardized Roadside Hardware .

(a)Wood. Treat according to AASHTO M 133.

(b)Steel. Provide steel conforming to Subsection 724.02(b) .

(c)Plastic or composite. Provide blockout s that are crashworthy. Provide a new homogeneous blockout with uniform texture that does not crack, chip, flake, peel, or splinter after fabrication.

724.04Guardrail Hardware. Provide hardware conforming to TF13, Guide to Standardized Roadside Hardware . For angles, channels, wide flanges, and plates not contained in TF13, conform to ASTM A36 for non -weathering steel and ASTM A242 for corrosion resistant (weathering) steel. For structural tubing for short steel posts, conform to ASTM A500 or ASTM A513, Grade 1008. Galvanize soil plates and structural tubing according to AASHTO M 111. Do not punch, drill, cut, or weld the metal after galvanizing. Provide a flexible hinged guardrail delineator that allows the reflector to fold down and spring back to an upright position after impact. Provide retroreflective sheeting conforming to ASTM D4956, including supplementary requirements. Use Type IV or XI reflective sheeting permanently adhered to 0.090- inch minimum thick body. Manufacture reflector tabs from 0.15 -inch aluminum or plastic. Use an adhesive that resists peeling with a force of 5 pounds per inch of width. Use mildew resistant adhesive that has no staining effect on retroreflective sheeting. Provide nuts, bolts, and cables conforming to the following:

(a)Galvanized nuts and bolts. Provide nuts conforming to ASTM A563, Grade A. Provide bolts conforming to ASTM A307, Grade A.

(b)Corrosion resistant (weathering) nuts and bolts. Provide nuts conforming to AS TM A563, Grade C3. Provide bolts conforming to ASTM A449, Type 3. (c) Cable. Provide cable conforming to AASHTO M 30, Type II, Class A.