SCOPE
720.01.01 Materials Covered. This specification covers the quality and kind of material used in the
construction of guardrail. REQUIREMENTS
720.02.01 Certificates. Furnish 2 certified copies of mill test reports showing the chemical and physical
characteristics from each heat from which metal is used. Rail members, bolts, nuts, and other fittings shall be interchangeable with similar parts regardless of source. PHYSICAL PROPERTIES AND TESTS
720.03.01 Rail Members. The beam -type members, comprised of rail members and end or terminal pieces,
shall conform to AASHTO M180, Type I, Class A, except galvanize after fabrication.
720.03.02 Fittings. All bolts, nuts, washers, and other fittings for beam -type guardrail shall be galvanized steel
meeting AASHTO M180. All bolts, nuts, and washers shall be 16 mm (5/8 in.) size. Bolts shall be button- head style and nuts shall be hexagonal. Bolts and nuts shall be coarse- threaded [11 threads per 25 mm (1 in.)], with nuts tapped oversize not to exceed 0.8 mm (1/32 in.). Outside dimensions of boltheads, nuts, and washers shall have the following minimums: boltheads, 32 mm (1 1/4 in.); nuts, 24 mm (15/16 in.); and washers, 38 mm (1 1/2 in.). Splice bolts shall be 32 mm (1 1/4 in.) in length, and post connection bolts shall be of lengths required to fit the post dimension and extend beyond the tightened nuts thereon within limits of 6 to 13 mm (1/4 to 1/2 in.). Provide washers, 3 mm (1/8 in.) thick, for use under nuts on all post bol ts, and under any nut which has a width of less than 27 mm (1 1/16 in.). Bolts for guardrail to barrier rail and guardrail to bridge rail connections shall be of lengths required to fit the dimension and extend beyond the tightened nuts thereon within lim its of 6 to 13 mm (1/4 to 1/2 in.). Galvanize fittings according to Section 715.
720.03.03 Guardrail Anchor Hardware. Provide cable and fitting for guardrail anchors that conforms to
AASHTO M30, Class C, for Type II cable. Galvanize all fittings according to AASHTO M111.
720.03.04 Metal Guardrail Posts. Metal posts shall be of structural steel conforming to ASTM A36 and
galvanized according to AASHTO M111.
720.03.05 Wood Guardrail Post. Wood posts and blocks shall be rough or surfaced to the dimensions shown
in the plans and shall conform to Section 718. SECTION 721 OBJECT MARKERS AND GUIDE POSTS SCOPE
721.01.01 Materials Covered. This specification covers the quality and kind of materials used in the
construction of object markers and guide posts. REQUIREMENTS
721.02.01 Certificates. Furnish 2 certificates covering each order of material (plates, reflectors, and posts) by
the manufacturer, certifying that the product complies with the specifications. Deliver certificates at the time of, or before, delivery of the order. PHYSICAL PROPERTIES AND TESTS
721.03.01 Metal Posts. Posts shall be steel conforming to ASTM A 1011, Grade 275 (Grade 40), or ASTM
A653, Designation SS, Grade 275 (Grade 40), and be of 3.2 to 3.5 mm (10 or 11 gage) thickness. Galvanize metal posts according to Section 715, or ac cording to ASTM A653, coating designation Z700 (G235).
721.03.02 Target Plates. (a) Base Metal. Base metal for target plates shall be zinc -coated steel sheet or
aluminum sheet. The zinc -coated steel sheet shall comply with FSS QQ -S-775 Steel Sheet, carbon, zinc -coated Type 1, Classes d and e, except that the zinc -coated surface shall withstand a 180 degree bend on itself at room temperature without flaking the coating. Prepare the zinc -coated surface for painting by the application of phosphate coating. Accomplish the phosphatizing process without damaging or removing the galvanized coating from the steel base metal. Any evidence of damage or removal of the zinc coating shall be cause for rejection of the entire lot. Prepare the aluminum sheet for paintin g with a chemical conversion coating conforming to MIL- C-5541. Apply the coating according to the manufacturer’s specifications and recommended sequence of operation. Furnish 2 copies of certified mill tests of the aluminum sheets. Fabricate target plates from 1.0 mm thick (20 gage) steel sheet or 1.3 mm (0.05 in.) thick aluminum sheet, alloy 3005- H14 conforming to ASTM B209. Accomplish fabrication of all metal parts in a uniform and workmanlike manner. Cut plates to size and shape and punch the holes for mounting bolts and reflectors according to the details shown on the plans. Provide surfaces and edges of the plates free from defects resulting from fabrication.
b.Paint. Target plates shall have satisfactory paint adherence. Furnish metal reflector plates for metal guide posts with one or both sides coated with a black, baked enamel finish. If only one side is coated, the coated side shall face oncoming traffic. Coat the plates with baked enamel conforming to the following provisions: The enamel finish coat for plates shall comply to Federal Specification TT -E-489, Class B baking type enamel. Apply the enamel by spraying, rolling, or dipping. Other methods may be used provided they are approved before use. The dry film thickness of the baked enamel coating on the galvanized steel plates shall be not less than 50 μm (2 mils). The dry film thickness on the aluminum plates shall be not less than 38 μm (1.5 mils) if enamel is applied by spray or dip method and not less than 25 μm (1 mil) if enamel is applied by continuous roller coat method. Provide uniform coating which is smooth and free from flow lines, streaks, blisters, or other surface imperfections. Provide finished plates without dents and defects. The maximum surface deviation from a horizontal plane on which the finished plate lies shall not exceed 6 mm (1/4 in.).
Source: Nevada Standard Specifications for Road and Bridge Construction, 2014 Edition. Pages 571–572 of 610.