9-2 Section 901
901-1 Description
Fabricate and furnish signs, including sign face, supporting fr ames, hardware and package th e signs for shipment.
901-2 Materials
Refer to Division 10. Item Section Retroreflective Sheeting 1092 -2 Signs and Hardware 1092 -1 RFID T racking Program (A, B, and D Signs) 1030 -1, 1030 -2, 1030 -8
901-3 Construction Methods
A.General Details concerning the fabrication and erection of the signs are shown in the contract. Sign designs not shown in the contract are avail able from the Engineer. Fabricate all items within 1/8 inch of design measurements. Scribe each sign, shield, arrow, overlay or blank on the back with the month and year . Do not begin fabrication of Type A and B signs until S -dimension verification revisions have been approved by the Engineer . Provide mounting holes in the Z-stringers of the signs in accordance with the details shown in the contract or approved shop drawings. Provide a space between the Z -bar and backing strip not greater than 1/8 inch. Date the erection of all signs and sign assemblies using printed self -adhesive label s designed for punching the appropriate day, month and year numbers with a hole punch. Place the label on the back of each sign in the lower corner nearest the roadway. The Sign Fabricator will provide a sufficient quantity of the label s for each sign. For Type A , B and D signs, p rint on the back of each sign the size of that sign ( e.g. 144 inches x 48 inches ) with black vinyl characters at least 4 inches in height and located in the bottom right corner on the back of the sign . The self-adhes ive installation date label shall be located near the vinyl characters and should include a Departmental approved RFID tag/label in accordance with Section 1030. Ship all multi- panel signs to the project intact, completely assembled and ready to be installed . Fabricate signs taller than 12 f eet as two separate signs with a horizontal splice, ready to be spliced and installed . Unless approved by the Engineer, no assembly other than a horizontal splice will be permitted except when a route shield or copy is required to be attached because of the horizontal splice.
B.Department and Contractor Furnished Signs Use t he contract to determine whether the signs are to be fabricated and furnished by the Contractor or whether the Department will provide them to the Contractor. For both Department and Contractor Furnished Signs, the Contractor provides all mounting hardware consisting of, but not limited to, shims, backing plate s, mounting bolts, washers and nuts. The sign fabricator will provide vertical Z -bars required for attaching seconda ry signs to the primary signs. Confirm in writing at least 4 months in advance, the actual date the Department furnished signs will be requi red. The signs will be made available to the Contractor for pickup at the
9-3 North Carolina Department of Public Safety sign fabrication facility on N .C. 39 near Bunn,
North Carolina, unless otherwise indicated in the contract . Provide for all transportation. The Engineer will inspect and approve the signs before they are packaged and crated for shipment. Take delivery of all signs within 60 days of the date requested or the date they are made available, whichever occurs last, and within 96 hou rs of receiving the first sign. The Engineer shall approve any exception to the above delivery procedure. At the time the signs are delivered to the project, provide to the Engineer one copy of the sales ticket furnished with the signs. After taking possession of the signs, the Contractor is responsible for any damage or theft that occurs to signs before final acceptance by the Engineer. Comply with the reflective sheeting manufacturer's recommendations for handling, transporting, erecti ng and storing of the signs. Acceptably repair or otherwise correct any damage to the signs or refabricate them. When requested by the Contractor, the Department may have the necessary repairs made or the signs refabricated , and deduct the associated cos t thereof from monies due the Contractor .
C.Signs Construct all signs, supporting frames and assemblies in accordance with the details shown in the contract and Tables 901 -1 and 901- 2. TABLE 901-1 SIGN TYPE PARAMETERS Sign Type Vertical and Horizontal Dimensions 144"x 48" Aluminum Panels Horizontal Z-Bars Aluminum Thickness A Vertical or Horizontal > 144 " or Vertical and Horizontal > 48 " Multiple Yes 0.125" B Vertical and Horizontal ≤ 144" and Vertical or Horizontal ≤ 48" Single Yes 0.125" D - Single No See Table 901-2 E - Single No See Table 901-2 F - Single No See Table 901-2
1.Type A Signs Fabricate Type A signs from multiple aluminum sheet increments of the thickness shown in Table 901 -1, with welded studs for attachment to the supporting frame. Use aluminum sheets with increments of 4 f eet in width; except, for sign widths that are not multiples of 4 f eet, a maximum of 2 panels may be cut t o less than 4 f eet. No panel may be cut to less than one foot. Mount aluminum sheet increments vertically and provide with backing strips at the vertical joints, held firmly in place, to keep the abutting sheets in proper alignment. Leave a space of 0.0 20 inch to 0.032 inch between each panel sheeted with non- prismatic sheeting. Prismatic sheeting is be trimmed at a 45° angle from the edge of each panel. Fabricate signs with a height of 12 f eet or less, without horizontal joints. No more than two horiz ontal joints will be permitted for signs that are more than 12 f eet in height. Locate the joint near the mid- height of the sign. Construct this joint according to the details in accordance with the contract.
9-4 (2) Type B Signs
Fabricate Type B signs from a single aluminum sheet of the thickness shown in Table 2 901-1, with welded studs for attachment to the supporting frame.
3.Type s D, E and F Signs and Milemarkers Fabricate Types D, E and F signs and milemarkers from single sheets of the thickness shown in Table 901 -2, with holes for bolting to the supports. Construct Type s E and F signs in accordance with the FHWA Standard Highway Signs . Adequately identify each individual sign to the correct assembly. Following the erection of Type E and F sign assemb lies, leave the identification markings on the individual signs until Department personnel have verified compliance with these requirements.
4.Overlays for Existing Signs Manufacture all overlays for existing signs of the thickness shown in Table 901 -2. Do not make holes for rivets in the overlays during fabrication, but instead field -drill them during the erection process.
D.Aluminum
1.Thickness Requirements TABLE 901-2 ALUMINUM THICKNESS REQUIREMENTS FOR SIGNS Vertical or Horizontal Dimension Minimum Thickness Inches Inches
0-11.9 0.032
12-35.9 0.063
36-47.9 0.080
48 and larger 0.125 Milemarkers 0.080 Overlays 0.063
2.Preparation of Aluminum Sign Surfaces Do not handle any metal, except by appropriate handling devices or by workmen wearing clean gloves, between the beginning of the coating operations and the completion of the application of the retroreflective sheeting. Retreat aluminum sign surfaces that come into contact with grease, oils or other contaminants before the application of retroreflective sheeting. Before applying retroreflective sheeting to the aluminum, treat the aluminum sign surfaces with a chromate conversion coating. Such coating shall be applied according to the manufacturer's instruction and shall conform to ASTM B449, Class 2, and should range in color from silvery iridescent to pale yellow. The coating weight shall be 10 mg/sf to 35 mg/sf on the entire surface area including along the edges of the sign substrate with a median of 25 mg/sf as the optimum coating weight. Ensure the coating does not appear dusty when wiped with a clean, lint -free cloth and does not show excessive buildup at edges. Sand smooth all burrs and scratches before applying retroreflective sheeting . Sheet all sanded aluminum within the same day to prevent the formation of corrosion on the metal. Do not sand or use abrasive materials on sheeted faces. Aluminum products shall be randomly tested.
E.Supporting Frames Use supporting frames for Type s A and B signs consisting of 2 or more horizontal aluminum Z -stringers with vertical aluminum bar stiffeners in accordance with the details
9-5 and dimensions shown in the contract . Use a nylon washer to attach all thru bolts with
a play of at least 1 /16 of an inch and no more than 1/8 of an inch . Provide stringers with necessary holes and slots for bolting stiffeners, attaching aluminum sheet increments and mounting to supports. Do not field drill holes in any part of the structural assembly, except the field drilling of horizontal Z -bars for attaching new signs to existing supports when necessary.
F.Welding Weld studs to aluminum sheets by the capacitor discharge method. If the s tuds are welded after the retroreflective sheeting has been applied, e nsure that burn- through does not damage the retroreflective sheeting. Shoot a test stud on each Type A and B sign in the lower left corner of the most left panel facing the back of the s ign.
G.Retroreflective Sheeting Apply retroreflective sheeting to the aluminum sign panels in accordance with the retroreflective sheeting manufacturer's recommendations. For each multi -panel increment sign using glass beaded materials, sheet the entire sig n from the same roll. If a sign panel needs to be replaced after sign fabrication, the replacement panel may be sheeted with retroreflective materials from a different lot or drum number than the remainder of the sign; however, use material that visually c olor matches and meets Article 19 1092 -2. Take retroreflectometer readings on all 4 corners of each panel and document the readings on the sign design drawings. Overlap all splices of any encapsulated or enclosed lens sheeting to allow water to run off without running into the splice. All prismatic sheeting will be butt spliced. Remove all foreign materials on the sheeted face with compressed air. Keep a sample of each roll of sheeting and test for retroreflective compliance. Patch wrinkles in the shee ting around thru bolts by removing the affected sheeting from the metal. Then patch this area with a circular patch encompassing an area 1/4 inch outside the affected area. This patch shall not exceed the standard patching limits shown in Table 901-3. Ensure that all patches on the sign have a 1 inch minimum width or as recommended by the sheeting manufacturer. Maintain documentation of the lot, drum, inspector, roll size, date received, date sheeted and metal treater on all signs, slip sheeting, copy, borders, shields, overlays, arrows and panels and retroreflectometer readings. Obtain and assign to the Department in writing warranties for sign sheeting used in the fabrication of all permanent signs from the s heeting manufacturer. Warrant the signs against defective sheeting per the requirements outlined in the contract. Define “p ermanent signs ” as Types A, B, C, D, E and F signs, overlays for all sign types and milemarkers , and exclude any signs used only for traffic control while the project is under construction. The reflective sheeting may be patched to repair incidental damage to the sheeting that might occur during manufacture, in transit or after installation; however, the patches cannot exceed the limits in Table 901 -3.
9-6 Table 901-3
SIGN PATCHING LIMITS Sign Area Maximum Number and Size of Patches During Fabrication Maximum Number and Size of Additional Patches After Field Erection Square Feet Max. Number per Sign Max. Size in Sq.In. Max. Number per sign Max. Patch Size in Sq.In. 0 to 15.0 0 0 0 15.1 to 50.0 (Single Panel) 1 1 1 30.0 to 80.0 (Increment Panel) 2 2 1 80.1 and Greater A 3 A
A.Average not to exceed one patch per panel per sign. Maximum of 3 patches per panel allowed during fabrication with one additional patch per panel allowed after field erection.
H.Reflectorized Letters, Numerals, Symbols, Border and Shields
1.General Use direct -applied retroreflective sheeting , approved digital i maging or demountable retroreflective sheeting letters, numerals, borders, shields and arrows as indicated on the sign designs. Use designs of letters and numerals that conform to the MUTCD and FHWA Standard Highway Signs and Markings . Use border widths, design of route shields and arrows that conform to the MUTCD. Route shields used on Type A or B signs or overlays shall be demountable or as approved digital imaging. Space and size all legends and borders in accordance with the contract or approve d shop drawings. Any loose, deformed or misplaced legends and borders will be cause for rejection of the entire sign.
2.Direct Applied Provide direct -applied reflectorized letters, numerals, arrows and borders that are of the type and color of retroreflecti ve sheeting shown in the contract for each sign. All direct applied copy or border not permanently affixed may be removed and replaced on signs if necessary during manufacture.
3.Demountable Attach demountable letters, numerals, borders, shields, arrows and alphabet accessories directly to sign faces with rivets as shown in the contract. Use letters, numerals, arrows, borders and shields made of adhesive -coated retroreflective sheeting, permanently adhered to a flat aluminum backing, in accordance with the c ontract. Use aluminum backing of at least 0.032 inch thick aluminum sheet ing of 3004- H38, 5052 -H38 or 6061- T6 alloy. Treat with a light, tight, amorphous chromate -type coating in accordance with the recommendations of the retroreflective sheeting manufact urer. Apply the retroreflective sheeting to the properly prepared aluminum using the method and equipment prescribed by the sheeting manufacturer.
9-7 Supply each letter, numeral, arrow, border and shield with mounting holes, and secure
to the sign surface wi th non- twist corrosion resistant aluminum rivets. Use letters, numerals, arrows and borders that have rivets on all sides and ends spaced not more than 6 inches on centers, measured along the edges. Make sure that each legend piece has at least one rivet in each corner and at least 2 rivets in each end. Attach route shields as part of Type A or B signs with aluminum rivets spaced not more than 9 inches apart, measured al ong the edges of the shield. Use a 1/4 inch diameter nylon washer under the head of all pull through type rivets for all demountable copy and shields.
4.If approved, use digital printing equipment to image or reverse image on retroreflective sheeting for letters, numerals, borders, shields and arrows on digitally approved retroreflective sheeting for traffic control signs on aluminum or digitally printed traffic sign faces intended to be applied to a sign substrate.
I.Silk Screening Apply all legends and borders on Type E and F signs by silk- screening o r reverse silk-screening after the sheeting is attached to the panels. Perform all screening as recommended by the manufacturer of the retroreflective sheeting. Use the color of all legends, borders and backgrounds, and their placement on the sign, in accordance with the contract. Use opaque black ink for nonreflectorized message application, as manufactured or recommended by the manufacturer of the retroreflective sheeting. Use transparent ink and thinner, for application on signs reflectorized with whi te retroreflective sheeting, as manufactured or recommended by the manufacturer of the retroreflective sheeting. Use colors that conform to the FHWA Color Tolerance Charts and AASHTO M 268 when thoroughly dry. Test all lots of transparent ink for compliance with the minimum coefficient of retroreflection equal to 70% of the specified minimum retroreflection of the corresponding sheeting color and document the retroreflection value. Inspect the first 5 signs of each screening and then every fifth sign. Whe n unacceptable signs are found, all signs shall be inspected individually. Only 3 nonwets per sf , no larger than 1/16 inch in diameter, covering no more than 1/3 of the total area of the sign are allowable. This includes nonwets from either the sheeting or the screen -printing. Only one tadpole per 6 sf, no longer than 1 1/2 inch and not readily visible under lighted inspection is allowable.
J.Mounting Hardware Prov ide all mounting hardware consisting of, but not limited to, shims, backing plates, mounting bolts, washers and nuts. Provide mounting holes in the Z -stringers of the ground mounted signs in accordance with the details shown in the contract.
K.Packaging, Sh ipping and Stor ing Protect all signs during shipment and storage. Before shipping, make sure that all signs are free of moisture and that all inks are thoroughly dry. Do not apply adhesive tapes to any sign surface. Keep all packaged signs entirely dry. Use assembled or partially assembled signs other than flat sheet signs that have sufficient braces securely attached to prevent buckling or warping at all times.
9-8 Affix a label outlining the retroreflective sheeting manufacturer's recommendations for
handl ing, transporting and storing all types of signs to each shipping carton or crate. Provide full details of such recommendations with each shipment of signs. Label each crate or package of signs or panels as to the contents (arrows, shields, etc.), WBS number and sequence of packages if more than one package is for a single sign. Maintain documentation of the lot, drum, inspector, roll size, date received, date sheeted, metal treater on all signs, slipsheeting, copy, borders, shields, overlays, arrows , panels and retroreflectometer readings. Individually rack or separate by foam or slip sheeting on A -frame racks all sheeted panels. Do not use spliced, overlapped, ripped or torn slipsheeting or foam. Store all p acked signs standing at a 75° to 90° angle. Turn all panels and sign faces to the inside of the crates, whenever possible. When crating a one -panel sign, provide the face side with an extra piece of foam and cardboard taped to the outside of the face side of the package. Pack panels of 102 inches in length or longer in only 2 per package. Ensure all signs are debris free on the back side, with no misplaced writing, tape or extraneous sheeting. Crate to allow a 2 inch space on the inside dimensions larger than the size of the largest package. Store com pleted Type A and B signs back to back with at least 12 inches between faces. When crating 2 panels of different sizes, place the smaller panel with its face to the back of the larger panel and package with an extra piece of foam and cardboard taped to the outside of the larger panel, with its face to the outside of the crate. Provide extra packaging on both outsides of the package for double -faced signs. Crate packaged panels to allow the passage of a 1/8 inch spacer on the inside of each side of the crat e, so that the panels are not overly tight or binding in crate. Inspect all signs and packaging before shipping to assure compliance with the contract. The Department retains the right to inspect the signs and packaging before shipping.
L.Transparent Films Use transparent films instead of silk screening when authorized by the Department. Transparent film is a durable, transparent, acrylic colored film coated with transparent, pressure -sensitive adhesive. When the film is applied over reflective sheeting, t he coefficient of retroreflectivity shall meet the color and type of sheeting in Tables 1092-3, 1092 -4 or 1092- 5. Use Department approved transparent film approved by the manufacturer of the reflective sheeting to ensure the materials meet the manufacturer’s warranty and o bligation in Subarticle 1092- 2(B).
M.Digital Printing Use digital Printing instead of silk screening or transparent films when authorized by the Department. Digital print technologies consists of digital re flective sheeting, digital ink systems, and clear overlay film. The manufacturing application process and the materials must be approved by the sheeting manufacturer to e nsure it meets the manufacturer’s warranty and obligation in Subarticle 1092- 2(B). The manufacturer m ay apply all legends and borders on Type E and F signs using digital printing. Use opaque black ink for nonreflectorized message application, as manufactured or recommended by the manufacturer of the retroreflective sheeting.
9-9 Retroreflective sheeting shall consist of white or colored sheeting having a smooth outer
surface and that essentially has the property of a retrorefl ector over its entire surface. Retroreflective sheeting shall conform to all requirements to the FHWA Color Tolerance Charts and AASHTO M 268 when thoroughly dry Digital printed ink systems used to print traffic signs must meet and comply with daytime and nighttime chromaticity (color standards) as recognized in ASTM D4956. Digital printed ink systems must meet 70% of the initial retroreflectivity in T able 1092- 3 and the coefficient of retroreflectivity for color and type of sheeting in Tables 1092- 3, 1092 -4 or 1092- 5. All digital inks and digital reflective sheeting shall be listed on the NCDOT APL and tested on AASHTO Product Evaluation & Audit Solutions test deck for 3 years prior to consideration to ensure the digital printed ink system meets the warra ntee obligation s listed in Subarticle 1092- 2(B) for the respective sheeting grade. Permanent traffic signs printed with digital ink systems will be fabricated with a full sign Protective Overlay Film designed to protect the entire sign from fading and UV degradation. The over laminate will comply with the retroreflective sheeting manufacturer’s recommendations to ensure proper adhesion and transparency and will also meet the reflective film durability in Subarticle 1092 -2(B). Temporary signs printed with black ink only will not require a p rotective overlay film as long as the finished sign is warranted for a minimum outdoor durability of three years by the sheeting manufacturer.
901-4 Sign Quality
Provide signs that present a uniform appearance free from color match problems, non- uniform color, streaks, spots, abrasions, blistering or other defects in the sheeting. Sheeting may be inspected before application to sign blanks, after installation to sign blanks, after completion of the sign in the sign fabricator's facility and after installation. Clean all installed signs before final field inspection. The retroreflective sheeting will be unsatisfactory if it has deteriorated due to any cause except defacement resulting from vandalism or damage resulting from impact by a motor vehicle or other object to the extent that:
A.The sign is ineffective for its inten ded purpose when viewed from a moving vehicle under normal day and night driving conditions, or
B.The coefficient of retroreflection is less than the minimum specified for that sheeting as shown in Tables 1092 -3, 1092 -4 or 1092- 5 when measured by a Departmen t approved retroreflectometer, or
C.The screened message and border or reverse screened background has stained, discolored, streaked, faded, turned dark or has developed cracks, scaling, pitting and/or blistering, or
D.The sign is unsatisfactory with regard to uniform appearance due to cracking, streaking, delamination, blistering, crazing or discoloration of the sheeting, or
E.The sign is unsatisfactory with regard to remaining uniform in color over the entire reflecting surface both day and night and displaying the same color both in daylight and under lights at night.
1.For glass bead material, sheeting will be subjected to a visual test with the human eye as the test instrument. Objectionable non- uniformity of color and reflectivity (retroreflection) under ligh t at night is cause for the sign to be tested for retroreflection to determine compliance with the following requirements:
Source: North Carolina Standard Specifications for Roads and Structures, 2024 Edition. Pages 394–401 of 857.