box shall be hot dipped galvanized with factory or field drilled conduit entrances. Provide a hot dipped galvanized cover with checkered imprint, pry bar slots, and reinforcing ribs for heavy loading, neoprene gasket, and brass or stainless steel bolts. Provide a blind tapped (1/4 inch NC thread minimum) boss on interior of box for grounding. 1091 -6 GROUNDING ELECTRODES Provide grounding electrodes of the following types as indicated in the specifications and plans.
Provide 5/8 inch diameter, 10 f eet long, copper -clad steel ground rods with 10 mil thick copper cladding.
Provide sectional ground rods comprised of 5/8 inch diameter, 10 f eet long, steel ground rods with 10 mil thick copper cladding, welded together in a butt configuration with an exothermic weld. As an alternative, provide U L listed bronze couplers designed to connect 5/8 inch diameter copper -clad steel rods. Do not use threaded ground rods or threaded couplers. Provide minimum lengths required by plans. SIGNING MATERIALS -1 SIGNS AND HARDWARE Fabricate signs from aluminum alloy sheets. Use supporting frames and accessories made of aluminum. Use galvanized steel backing plates and mounting bolts. Use materials that conform to Tables 1092- 1 and 1092- 2. Filler metal shall conform to AASHTO Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals , and the Interim Specifications as shown on the plans . Aluminum sign studs, welded to the sign panels in acc ordance with Article 901 -3, shall be capable of withstanding a direct pull -out load of 400 lb. Furnish a Type 3 material certification in accordance with Article 106 -3 demonstrating conformance to this requirement. The Materials and Tests Unit will take samples of the studs and make random field tests of the welded studs to verify the statement of certification. Failure of more than 5 % of the studs tested on any one sign or failure of 3 or more studs in a row will be sufficient evidence for rejection of stud welding on the entire sign. When tested in tension, the studs shall not fail in the weld area, but fail in the threaded portion of the stud. Corrective actions will be determined by the Engineer. Drill bolt holes and slots to finisheds ize or they may be punched to finished size, provided the diameter of the punched holes is at least twice the thickness of the metal being punched. Flame cutting of bolt holes and slots will not be permitted. No galvanizing of any steel part will be allowed until all welding, cutting, milling, punching, and drilling of the part has been completed.
TABLE 1092 -1 ALUMINUM SIGN MATERIALS Aluminum Materials Alloy Specification Test Method Extruded Bars 6061 -T6 ASTM B221 Sheets and Plates 6061 -T6,5052 -H38 or 3004 -H38 ASTM B209 Structural Shapes 6061 -T6 ASTM B308 Standard Weight Pipe 6061 -T6 ASTM B241 Castings 356-T7 ASTM B26 Bolts 6061 -T6, 2024 -T4A ASTM B211 Nuts (1/4" Tap and under) 2024 -T4A, 6061 -T6 or 6262 -T9 ASTM B211 Nuts (5/16" Tap and over) 2024 -T4A, 6061 -T6 or 6262 -T9 ASTM B211 Nuts (3/8" Self -locking) 2017 -T4, 6061 -T6 ASTM B211 Washers (std. flat) Alclad 2024 -T4A or 6061 -T6 ASTM B209 Washers (std. lock) 7075 -T6 ASTM B211 Welded Studs (1/4") 5356 -H12 or 5356 -H32 ASTM B211
dichromate or boiling water seal
TABLE 1092 -2 STEEL SIGN MATERIALS Galvanized Steel Materials Test Method for Base Metal Test Method for Galvanizing Structural Shapes and Plates ASTM A36 ASTM A123 Standard Weight Black Pipe ASTM A53 ASTM A123 Bolts and Nuts ASTM A307 ASTM F2329 Washers (std. flat and lock) ASTM A307 ASTM F2329 High Strength Bolts, Nuts and Washers ASTM A325 ASTM B695 Class -2 RETROREFLECTIVE SHEETING Reflectorize all signs. Use colors and sheeting grades of the sign backgrounds and messages as shown in the contract. After preparation of the sign panels, in accordance with Subarticle 901-3(D), apply retroreflective sheeting as required herein. The retroreflective sheeting shall consist of white or colored sheeting having a smooth outer surface and the property of a retroreflector over its entire surface. Retroreflective sheeting shall meet ASTM D4956 and be listed on the NCDOT APL. Products must be current with the applicable AASHTO Product Evaluation & Audit Solutions workplan to remain on the NCDOT APL. The reflective mat erial specified herein is intended for use on surfaces of various traffic control devices, including drums, barricades, traffic cones and highway signs, to assure their adequate visibility at all times upon exposure to a light source when totally dry or we t. Provide reflectorization that produces a wide- angle retroreflectivity, enhancing nighttime visibility. This retroreflective sheeting shall consist of encapsulated, enclosed lens or prismatic with a transparent plastic having a smooth, flat outer surfac e. Provide material that is flexible, of good appearance, free from ragged edges, cracks and extraneous materials, and exhibits good quality workmanship.
TABLE 1092 -3 MINIMUM COEFFICIENT OF RETROREFLECTION FOR NC GRADE A (Candelas Per Lux Per Square Meter) Observation Angle, degrees Entrance Angle, degrees White Yellow Green Red Blue Fluorescent Yellow Green Fluorescent Yellow 0.2 -4.0 525 395 52 95 30 420 315 0.2 30.0 215 162 22 43 10 170 130 0.5 -4.0 310 230 31 56 18 245 185 0.5 30.0 135 100 14 27 6 110 1.0 -4.0 80 60 8 16 3.6 64 1.0 30.0 45 34 4.5 9 2 36
TABLE 1092 -4 MINIMUM COEFFICIENT OF RETROREFLECTION FOR NC GRADE B (Candelas Per Lux Per Square Meter) Observatio n Angle, degrees Entranc e Angle, degrees White Yellow Green Red Blue Fluorescen t Yellow Green Fluorescen t Yellow Fluorescen t Orange 0.2 -4.0 5 38 76 17 300 230 115 0.2 30.0 2 22 43 10 170 130 0.5 -4.0 0 24 48 11 190 145 0.5 30.0 0 14 27 6 110 81 1.0 -4.0 80 60 8 16 3. 6 64 48 7.5 1.0 30.0 45 34 4. 5 9 2 36 27 5.6
TABLE 1092 -5 MINIMUM COEFFICIENT OF RETROREFLECTION FOR NC GRADE C (Candelas Per Lux Per Square Meter) Observation Angle, degrees Entrance Angle, degrees White Yellow Green Red Blue Brown 0.2 -4.0 250 170 45 45 20 0.2 30.0 150 100 25 25 11 8.5 0.5 -4.0 95 62 15 15 7.5 0.5 30.0 65 45 10 10 5 3.5 For areas printed with transparent colors, the coefficient of retroreflection shall not be less than 70% of the values for the corresponding color.
Meet ASTM D4956.