704.01 Material for Signs
704.01.1 Sheet Aluminum
Use aluminum alloy in accordance with the Aluminum Association alloy AA5052-H38 or AA6061-T6 requirements. Meet the sheet thickness requirements listed in Table 704-1. TABLE 704-1 SINGLE POST MOUNTING Sign Size Inches (mm) Thickness Inches (mm) Regulatory Series Without Back Bracing 0 to 33 (0 to 838) wide, inclusive 0.080 (2) 34 to 41 (864 to 1,041) wide, inclusive 0.100 (2.54) 42 to 51 (1,067 to 1,295) wide, inclusive 0.125 (3.17) Warning Series Without Back Bracing 30 x 30 (762 x 762) or smaller 0.080 (2) 36 x 36 (914 x 914) 0.080 (2) 48 x 48 (1,219 x 1,219) 0.100 (2.54) 60 x 60 (1,524 x 1,524) 0.125 (3.17) Delineator Reflectors All sizes 0.063 (1.6) All Signs With Back Bracing Maximum Back Brace Spacing Thickness Inches (mm) ≤ 32 (813) 0.080 (2) ≤ 40 (1,016) 0.100 (2.54) ≤ 50 (1,270) 0.125 (3.17) Use the sheet thickness shown in the regulatory series for the route marker series, using the widest point on the cut-out shield for the width dimension. Make all signs not listed above from 0.080-inch (2 mm) thick sheeting.
704.01.2 Aluminum Sheet Increment
Construct aluminum sheet increment signs using AA5052-H38 or AA 6061-T6 sheet aluminum (thickness in Subsection 704.01.1) fastened to an extruded T-section (AA6063-T6) back brace with 3⁄16-inch (5 mm) blind rivets. Use the back brace and rivet spacing shown in the Detailed Drawings. Use extruded T-sections weighing a minimum 0.88 pounds per linear foot (1.3 kg/m) with a minimum moment of inertia about the neutral axis of 0.40 inches4 (166.5 mm4). 704 – SIGNING MATERIALS 2020 EDITION V5.1 704-2
704.01.3 Aluminum and Steel Posts
A.General. Furnish posts meeting the contract requirements. Treat steel post field cuts and holes with one coat of metal primer and two coats of aluminum paint. Coat galvanized posts meeting AASHTO M 111 specifications.
B.Steel Posts.
1.Structural Steel. Furnish structural steel posts having a nominal weight exceeding 3 pounds per foot (4.5 kg/m) meeting ASTM A36 requirements. Bid these posts as “steel structural sign posts”. Paint the posts meeting the Detailed Drawing requirements.
2.Steel U Sign Posts. Furnish steel posts formed into a “flying U” shape meeting AASHTO M 281. Bid these posts as “steel U sign posts”.
3.Tubular Steel Posts. Furnish round tubular steel posts meeting ASTM A53 Type E or S, Grade B requirements. Furnish square or rectangular tube posts meeting ASTM A500 or A501 requirements. Painted or galvanized posts are acceptable. Meet ASTM A123 requirements for galvanizing. Paint the posts in accordance with the Detailed Drawing.
4.Square Tubular Steel Posts. Ensure that all square tubular perforated, and non- perforated steel post telescoping devices meet the velocity change criteria of the current AASHTO Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals. Furnish square tubular steel sign posts, anchor posts, anchor sleeves, and splice sleeves meeting one of the following requirements:
a.ASTM A653 Grade A steel in 10 or 12 gauge having a 33,000-psi (22.7 MPa) minimum yield strength and a 45,000-psi (31 MPa) minimum tensile strength.
b.ASTM A570, steel in 12 or 14 gauge having a 60,000-psi (41.4 MPa) minimum yield strength and a 75,000 (51.7 MPa) minimum tensile strength. Use ASTM A307 Grade 2 bolts and nuts. Ensure the sign posts, sleeves, anchor posts, auxiliary fittings and anchor sleeves have 7⁄16-inch (11 mm) diameter holes or knockouts on 1-inch (25 mm) centers on all four sides. The permissible pole straightness variation is 1⁄16-inch in 3 feet (1 mm/m) with the corner radius being 5⁄32-inch (4 mm) ± 1⁄64-inch (0.4 mm). Coat the post with Type 2 aluminum paint at a minimum 0.75 ounces per square foot (228 kg/m2) of surface area, measured by triple spot testing under AASHTO T 213. Follow with a chromate conversion coating, and a thin acrylic or polymer resin film; or a triple coating of hot dipped zinc weighing 0.60 ± 0.15 ounces per square foot (183 kg ± 4.3 kg/m
2.in accordance with AASHTO M 120, followed by a chromate conversion coating 15 ± 5 micrograms per square inch (645 mm2), and a clear organic coating 0.2 ± 0.1 mils (0.005 mm ± 0.0025 mm) thick on the outside surface. Provide double in-line application of a full zinc-based organic coating 1.2 ± 0.6 mils (0.003 mm ± 0.0015 mm) thick tested in accordance with ASTM B117 on the inside surface.
C.Aluminum U Posts. Furnish aluminum posts made of AA6061-T6 alloy extruded to a U- channel in accordance with ASTM B209.
D.Breakaways.
1.Structural and Tubular Steel. Furnish frangible bolt devices and reduced section (or perforated) fuse plates. Use devices commercially manufactured and designed in accordance with AASHTO’s current edition of Standard Specifications for Structural 2020 EDITION V5.1 SIGNING MATERIALS – 704 704-3 Steel Support for Highway Signs, Luminaires and Traffic Signals, crash tested and approved for use by FHWA.
2.Square Tubular Steel Posts. Furnish slip base breakaway devices in accordance with the Detailed Drawings. Ensure the breakaway device meets the velocity change criteria in accordance with AASHTO’s current edition of Standard Specifications for Structural Steel Support for Highway Signs, Luminaires and Traffic Signals, for both single tube and telescoping installations.
704.01.4 Treated Wood Posts and Poles
Timber poles are specified by the top diameter. Meet Table 704-2 top diameter limits: TABLE 704-2 TIMBER POLE - TOP DIAMETER LIMITS Specified Top Diameter inch (mm) Diameter Limits inch (mm) Min. Max. 3 (75) 3 (75) 4 (100) 4 (100) 4 (100) 5 (130) 5 (130) 5 (130) 6 (150) 6 (150) 6 (150) 7 (180) Furnish posts and poles 10 feet (3 m) in length or less free of crooks and sweeps greater than ¾-inch (19 mm) from the post centerline. The maximum offset from centerline for posts and poles longer than 10 feet (3 m) is ¾-inch (19 mm) plus 1⁄16-inch (2 mm) per additional foot of length. The centerline is defined as a straight line from the center of the tip to the center of the butt. Gain and chamfer posts and poles in accordance with the Detailed Drawings. Perform all machining before treatment. Pressure-treat all timber posts and poles in accordance with Subsection 706.04, regardless of length. Treat round posts and poles in accordance with AWPA Standards for Commodity specification B and use Category 4A, regardless of length. Supply round posts and poles meeting the AWPA minimum penetration requirements specified for natural posts and poles, with a penetration of at least ⅜-inch (9 mm). Posts and poles must have sufficient sapwood to provide the ⅜-inch (9 mm) minimum penetration. Gain each post and pole on the sign face at least 2 inches (50 mm) in width in accordance with the Detailed Drawings . Use construction grade 2 x 4-inch (38 x 89 mm actual thickness), pressure treated in accordance with Subsection 706.04, in S4S for back bracing.
704.01.5 Overhead Structures
Furnish overhead sign structures in accordance with the most current AASHTO LRFD Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals, including fatigue requirements in Section 11. Include fatigue design requirements for all sign structures in accordance with Table 704-3. 704 – SIGNING MATERIALS 2020 EDITION V5.1 704-4 TABLE 704-3 SIGN STRUCTURE DESIGN REQUIREMENTS • Design Wind • 700 MRI basic wind speed (115 MPH) • Gust Factor Effect (G) • 1.14 • Height and Exposure Factor • Kz, where α =9.5; zg = 900 ft. for exposure C • Design Area • Design area with respect to max wind load is perpendicular to the structure. • Design Weight • Dead Load and ice • Fatigue Category • 1 Include Galloping, Truck Induced Gusts (Use posted speed limit) and Natural Wind Gusts Design.
704.01.6 Concrete
Use Class General concrete in accordance with Section 551 for steel sign post foundations. Hand mixing is not allowed. Add an air entraining agent to all foundation concrete.
704.01.7 Retro-reflective Sheeting
Furnish ASTM D4956 Type XI retro-reflective sheeting for all signs.
A.Delineators. Furnish ASTM D4956 Type IV retro-reflective sheeting for all reflectors and panels.
B.Digitally Printed Signs. Digitally printed signs may be used if they meet the following requirements:
1.Submit the manufacturer’s certificate of compliance a minimum of 14 calendar days prior to sign installation. The certification of compliance must certify that the equipment, materials, operators, and processes have been certified by the sheeting manufacturer.
2.Digitally printed ink systems must meet ASTM D4956 color standards.
3.Follow the sheeting manufacturer’s quality control process during the manufacturing process.
4.Apply a clear UV protective overlay to the entire sign face. Ensure the overlaminate complies with the retroreflective sheeting manufacturer’s recommendations.
5.Furnish black inks that are entirely opaque.
6.Furnish signs free of printing lines. Ensure inks are homogeneously applied.
7.Store, handle, and transport signs in accordance with the manufacturer’s recommendations to prevent damage to the sign.
C.Letters - Direct Applied. Furnish letters, numerals, symbols, and borders from Type III sheeting, permanently adhered to the sign face reflective sheeting. Apply the letters, numerals, symbols, and borders following the sheeting manufacturer’s recommendations. Follow the size, series, and spacing in the FHWA’s Standard Alphabets proportion and spacing requirements. Use finished pieces that are clean cut, free of ragged borders.
D.Traffic Control. Furnish traffic control sheeting in accordance with ASTM retro-reflective sheeting on the traffic control devices specified in Table 704-4 . The following traffic control devices in the traffic control rate schedule require ASTM designated retro-reflective sheeting as specified. Provide orange sheeting that is fluorescent. All other sign colors need not be fluorescent: 2020 EDITION V5.1 SIGNING MATERIALS – 704 704-5 TABLE 704-4 ASTM RETRO_REFLECTIVE SHEETING REQUIREMENTS Traffic Control Rate Schedule Group No. Specification Type 1-15, 19, 25 (panel) and all other work zone sign faces (e.g., flag person paddles, pilot car signs, etc.) ASTM D4956 XI, X, IX VIII, VII or VI 27, and all cones and tubular markers ASTM D4956 III or V 17 ASTM D4956 IV or higher Reflective sheeting may only be overlaid on reflective sheeting of the same color. Remove any existing legend prior to overlaying.
E.Acceptance. Submit manufacturer’s certification that the retro-reflective sheeting used meets the designated ASTM type retro-reflective requirement specified. The Department may take sheeting samples for analysis and testing. The Project Manager may visually compare the sheeting’s diffuse day color in the field using standard color charts and test the signs retro-reflectivity using a retro-reflectometer. Replace rejected material at Contractor expense.
704.01.8 Paint
Use paints in accordance with Section 710.
704.01.9 Hardware
A.Miscellaneous. Use bolts, washers, nuts, lock washers, incidental hardware, and angles for erecting aluminum sheet signs that are:
1.Galvanized in accordance with ASTM A153 or ASTM B633; or
2.Aluminum alloy in accordance with ASTM B211 for alloy 2024-T4.
B.Hinges. Use only non-rusting hardware of like material. When mounting on Aluminum sheeting for folding signs, use hinges that are:
1.Aluminum alloy in accordance with ASTM B211 for alloy 2024-T4; or
2.Stainless steel in accordance with ASTM A276.
704.02 Fabrication of Signs
704.02.1 Aluminum Signs
Provide a reflectorized sheet background. Clean rust, white rust, oil, and dirt from the aluminum sheeting. De-grease the sheeting using vapor or alkaline de-greasing agent following the de-greasing agent manufacturer’s recommendations. De-grease, acid or alkaline etch, rinse, and dry the sheeting as recommended by the etching solution manufacturer. Treat the etched sheeting with a light, tight adherent chromate conversion coating before applying the reflective sheeting. This coating must not leave a powdery residue and may leave a silvery iridescence to pale yellow appearance. Coat in accordance with ASTM B921 or B449, Class 2, 10 to 35 milligrams thick per square foot (0.093 m 2). Hot air-dry the sheeting once coated. Apply and seal the reflectorized sheeting on the prepared aluminum sheeting following the reflective sheeting manufacturer’s recommendations. Apply legends and borders in accordance with Subsection 704.01.7(B) . 704 – SIGNING MATERIALS 2020 EDITION V5.1 704-6 Color the blind rivet heads to match the sign face. Apply background material to the sheet aluminum before fabricating the sign. Butt the sheet increments together to produce a joint that meets the specified tolerances limits. Do not use water to float the reflective sheeting or legends into place during fabrication.
704.02.2 Inspection and Acceptance
Completed signs will be inspected for acceptance. Signs will be rejected for defects including, but not limited to cracks, tears, splits, crazing, gouges and curled edges of background sheeting or legends.
704.03 Flexible Delineators
Furnish flexible delineators listed on the QPL . Flexible delineators must meet NCHRP 350 or Mash requirements. Delineator material must be impact resistant within a temperature range of −30 to +130 °F (−34.4 to +54.4 °C). Ensure the material from which the vertical tube post is fabricated flexes upon impact and results in little or no damage to impacting vehicles. Delineator must be ultra violet stabilized and resistant to ozone and hydrocarbons. Ensure the delineator design allows for quick and easy removal and replacement of delineator tube with only the use of common hand tools. Ensure the delineator is flexible, self-erecting to original position and capable of withstanding numerous impacts from a direction without splitting, breaking or detachment from the base or the surface to which the base is attached. Delineators must have a minimum height of 36 inches (915 mm) and width configuration that allows a minimum of 46.5 square inches (300 cm
2.of retro-reflective sheeting to be affixed at the top of the post. Retro-reflective sheeting must be placed within the top 9 inches (230 mm) of the delineator. Ensure color, area and configuration of retro-reflective sheeting equals that required by the standard drawings for the type of delineator specified. Ensure the post color matches the attached sheeting. Provide the mounting as specified in the contract.
A.Surface Mount Flexible Delineators. Ensure base material is flexible, high impact composite material with a maximum of 72 square inches (464 cm2) surface area and capable of being mechanically attached to the mounting surface.
B.Driveable Flexible Delineators. Ensure anchor is made of rigid materials and cannot collapse or buckle when driven into dense soil. Metallic materials must be galvanized. Ensure anchor is driveable with manual or common installation tools.
704.04 Linear Delineation Systems
Furnish a product that produces retro-reflection and high visibility across a very wide range of entrance and observation angles. Furnish a product that meets one of the following: • Fabricate the panels from Diamond Grade Reflective Sheeting, laminated onto a thin gauge of aluminum and formed to a unique shape, or • Bond an angular retro-reflective coating onto a structural substrate.
704.04.1 Concrete Barrier Rail.
Furnish panels that are a minimum 31 inches long and 6 inches high.
704.04.2 W-Beam Guardrail.
Furnish panels 26 to 36 inches long by 1½-inch wide.
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Source: Standard Specifications for Road and Bridge Construction, 2020 (v5.1) Edition. Pages 551–556 of 611. View official source ↗