Art. 1090.02 Sign Base Type 1 sign panels shall be at least 0.080 in. (2.03 mm) thick. Type 2 sign panels shall be at least 0.125 in. (3.17 mm) thick. All panels shall be a flat continuous section of the length, width and shape specified in the plans for Standard Sign Design Criteria of the MUTCD with specified mounting holes and corner radii. Sign panels shall be according to dimensions specified, within ±1/32 in. (±0.794 mm) and shall not be out of square more than 1/16 in. (1.588 mm). Warps and buckles shall not exceed 1/16 in. (1.588 mm) for each foot in length or width when laid on a true flat surface. All fabrication shall be accomplished prior to the chemical conversion coating process. Before retroreflective sheeting is applied to the sign panel, the application surface shall be thoroughly cleaned, prepared, or etched according to the sheeting manufacturer's recommendations. The chemical conversion coating shall remain intact on the backside of the sign panel. There shall be no opportunity for the clean metal surface to oxidize or come in contact with grease, oils, or other contaminants prior to the application of retroreflective sheeting or paint.
1090.03 Bolted Aluminum Extrusions. Sign panels of this type shall be made
of aluminum according to ASTM B 221, Alloy 6063-T6. Panel preparation shall be according to Article 1090.02, except etching may be omitted and holes for demountable sign legend units may be drilled after assembly and reflectorization. Sign molding shall be an aluminum extrusion designed for the sign panel extrusion with which it is to be used and its color shall match the color of the sign background. The sign molding shall be riveted to the sign panel on 2 ft (600 mm) centers. Aluminum dome head rivets shall be used to secure the sign molding, sign panel overlays, demountable legend unit, and supplemental panel to the sign face. The dome head rivets shall be 3/16 x 1/4 in. (4.75 x 6.35 mm) blind made from 5052 aluminum with an aluminum alloy mandrel. The dome head rivets shall have a grip range from 0.126 to 0.250 in. (3.2 to 6.4 mm) with a flange diameter of 0.114 in. (2.9 mm) and a rivet length of 0.450 in. (11.4 mm). The dome head rivets shall be color anodized according to the sheeting color of the unit being installed. All bolts, nuts, and other hardware and material used in assembling aluminum extrusions into sign panels shall be supplied by the manufacturer of the panels. Post clips shall be aluminum according to ASTM B 108 (B 108M), 356-T6. Bolts and washers shall be stainless steel according to ASTM A 276 (A 276M), Type 304. Nuts shall be stainless steel according to ASTM A 240 (A 240M), Type 304.
1090.04 Plywood. Plywood shall be according to AASHTO M 133. Each
panel shall bear the mark of an approved testing agency or independent testing laboratory. If slip sheets are used, they shall not deposit any wax, silicone, or other substance on the surface of the overlays. There shall be no caulk lubricant residue left on the surface of the overlays that will affect the adhesion of retroreflective sheeting. Sign Face, Sign Legend, and Supplemental Panels Art. 1091.02 Plywood sign panels shall not be used with Type A retroreflective sheeting. SECTION 1091. SIGN FACE, SIGN LEGEND, AND SUPPLEMENTAL PANELS
1091.01 Sign Face Material Requirements. The sign face material shall be in
accordance with the Department’s Fabrication of Highway Signs Policy. The sheeting for the background, legend, border, shields, and symbols shall be provided by the same manufacturer
1091.02 Sign Legend and Supplemental Panel Material Requirements. The
sign legend and supplemental panel material shall be in accordance with the Department’s Fabrication of Highway Signs Policy and the Illinois Manual for Uniform Traffic Control Devices. Signs shall be fabricated such that the material for the background, legend, border, shields, and symbols are applied in the preferred orientation for the maximum retroreflectivity per the manufacturer’s recommendation. When using Type ZZ retroreflective sheeting, the nesting of legend, border, shields, or symbols will not be permitted. Letters and numerals used shall be according to the standard alphabets for highway signs (available from the Federal Highway Administration) of the series indicated in the design details for the sign. The finished letters, numerals, symbols, panels, and borders shall show careful workmanship and be clean cut, sharp, and have essentially a plane surface.
a.If demountable copy is specified, each demountable legend unit and supplemental panel shall be supplied with mounting holes and shall be secured to the sign face with aluminum dome head rivets with aluminum mandrels and may not be held in place, even temporarily, using any type of adhesive that would damage the sign face, legend unit, or border when removed at a later date. All rivets shall be color matched to the legend or supplemental panel being installed.
b.Direct Applied Legend. All direct applied sign legend and borders shall be affixed to clean, dust-free sign panels in a manner specified by the legend manufacturer. The legend and border shall be cut neatly at any intersecting panel edge. Direct applied retroreflective sheeting and nonreflective sheeting used for legend and border shall be according to Article 1091.03. The sheeting may be manufactured with a thin aluminum layer between the sheeting and the precoated adhesive.
c.Flat Frames. The retroreflective sheeting and nonreflective sheeting used on flat frames for legend and border shall be according to Article 1091.03.
Referenced in this section
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Source: Illinois Standard Specifications for Road and Bridge Construction, 2022 Edition. Pages 1091–1092 of 1,217. View official source ↗