- 920 - SECTION 1070 -- HIGHWAY SIGNS
1070.01 Description
1.Materials authorized for use in constructing highway signs, Type A and Type B, are listed in this Section.
1070.02 Material Characteristics
1.Reflective Sheeting:
a.The reflective sheeting for sign reflectorization shall meet the requirements of ASTM D 4956.
b.All reflective sheeting for Type A and Type B signs shall be Type IV sheeting.
2.Overlay Panels:
a.Overlay panels for Type B signs shall be at least 0.04 inch (1 mm) thick sheet aluminum (ASTM B 209M Alloy 6061-T6) surfaced with reflective sheeting. The type and color of the reflective sheeting shall be as shown in the contract.
b.Panels cut from coil sheet will not be accepted. 3. Letters, numerals, symbols, and borders for “Type B Signs” shall be reflective materials meeting the requirements of ASTM D 4956 for Type IV sheeting direct applied or detachable copy.
4.Signs shall meet the size a nd shape requirements of the Manual on Uniform Traffic Control Devices for Streets and Highways.
5.Reflective background sheeting for all signs shall conform to ASTM D 4956.
6.Routemarkers: a. The State, U.S., and Intersta te Highway routemarkers to be used as legend units on Type B signs shall be fabricated from at least 0.08 inch (2 mm) thick sheet aluminum alloy 6061-T6 (ASTM B 209M) and shall be processed in accordance with the reflective sheeting manufacturer's recommendations.
b.Reflectorized sheeting shall conform to AASHTO M 268. c. Color and sizes of routemarke rs shall be shown in the contract.
d.The routemarkers shall be attached to the sign background in the same manner as the other legend units.
e.Special designs on the Stat e routemarker shall be obtained from the Department’s Traffic Engineer.
7.Supports:
a.Supports for Type A and Type B signs shall be steel beam or wood breakaway posts. The size, shape, construction, and weight per foot (meter) shall be specified in the contract.
b.The sign supports shall be cut off at the same elevation as the top of the sign.
c.The steel beam breakaway posts and stub post steel shall comply with ASTM A 36/A 36M with a working stress of 20,000 psi (138 MPa). Highway Signs 1070.02 - 921 - d. After all post fabrication is completed, the posts shall be hot- dipped galvanized in accordance with ASTM A 123.
e.The steel for base connection plates and fuse plates shall comply with ASTM A 36/A 36M. The fuse plate shall be hot-dip galvanized in compliance with ASTM A 123.
f.The base connection and fu se plate bolts, nuts, and washers shall be as shown in the contract and galvanized to conform with ASTM A 153.
g.The stub post shall be hot-dip galvanized in accordance with ASTM A 123 after all holes have been drilled, slots cut, and base plates welded. The galvanizing shall extend a minimum of 6 inches (150 mm) below the base plate.
h.Treated timber sign posts sha ll conform to the requirements of Subsection 1075.06.
8.Brackets and Fasteners: a. Mounting brackets for Type A signs shall be aluminum alloy 6063-T6 (ASTM B 221M) or steel (ASTM A 36/A 36M) galvanized to conform to the requirements of ASTM A 123. Thickness and dimensions shall conform to those shown on the contract.
b.The steel sign bolts for Type A signs shall be stove bolts 3/8 inch (9 mm) in diameter and in lengt hs as required. The steel bolts, nuts, and washers shall be in accordance with Section 1058.
c.An aluminum angle, 1 1/2 inch x 1 1/2 inch x 0.188 inch thick (38 mm x 38 mm x 4.75 mm thick) for use with extrusheet and extruded sign brackets on wood posts, shall be alloy 6061-T6 complying with ASTM B 308/B 308M.
d.Post clips shall be aluminum alloy 356.0 conforming to ASTM B 108. Post clips and sign bracket bolts shall be aluminum alloy 2024-T4 conforming to ASTM B 211. Locknuts for aluminum bolts shall be aluminum alloy 2017-T4 conforming to ASTM B 211M.
e.The sign brackets and fastene rs specified above shall not be paid for directly but shall be considered subsidiary to the items for which direct payment is made.
9.Type A and B Backing Material: a. Type A signs shall be fabr icated from Alloy 6061-T6 or 5052- H38 (ASTM B 209M) sheet aluminum.
1.The sign blanks shall be free from laminations, blisters, slivers, open seams, pits from heavy rolled-in scale, ragged edges, holes, turned down corners, or other defects which may affect their appearance or use.
2.All blanks shall be uniform in thickness and flat. (3) All shearing, cutting, and punching shall be done before preparation of blanks for application of reflectorizing material.
i.The sheared edges of all blanks shall be straight and free from tears and raggedness. (ii) All corners shall be rounded as shown in the contract.
1070.02 Highway Signs
- 922 - (iii) All punched or drilled holes shall be round and free from tears, raggedness, or distortion of the metal.
4.Sign blanks cut from coil sheet will not be accepted.
5.All thicknesses shall be as required in the contract. (6) All sign blanks shall be given a chromate conversion coating meeting the requirements of ASTM B 449 Class 2. The chromate coating shall be suitable for use as a paint base and for corrosion protection.
b.Type B Signs shall be fabr icated from extrusheet panels constructed of Alloy 3003-H18 (AST M B 209M) flat sheets and Alloy 6063- T6 or 5052-H38 (ASTM B 221M) extruded stiffeners. The flat sheets shall be at least 0.08 inch (2 mm) thick, and the stiffeners shall have the dimensions shown in the contract. The panels shall be made in widths of 12 inches, 18 inches, 24 inches, and 36 inches (300 mm, 450 mm, 600 mm, and 750 mm) as specified in the contract.
1070.03 Acceptance Requirements
1.Materials for highway signs will be accepted on the basis of compliance with the requirement s of these Specifications. - 923 - SECTION 1071 -- POSTS AND FASTENERS FOR HIGHWAY SIGNING
1071.01 Description
1.This Section covers galvaniz ed or painted enamel steel posts, flexible posts, and zinc or cadmium plated fasteners for use in highway signing for other than Type A and Type B signs.
1071.02 Material Characteristics
1.a. Sign posts shall be a st andard "U" or channel shape. The posts shall be flange type, and the length shall be shown in the contract. The posts may be light or heavy duty.
b.Steel posts for signs shall be made from hot-wrought carbon steel or rail steel conforming to t he requirements specified in ASTM A-702 (Steel B).
c.All holes shall be at least 3/8 inch (9.5 mm) diameter. They shall be punched or dril led in each post and spaced 1 inch (25 mm) from center to center, ±1/16 in ch (+1.5 mm), beginning with the first hole at 1 inch (25 mm) from the top of the post. Punchi ng shall be done so that there will be no cracks or burs radiating from the holes.
d.(1) Painted posts shall be cleaned of all loose scale before finishing and painted with one or more coats of weather resistant enamel (black or green, as specified).
2.The finish shall produce a glossy appearance with satisfactory elastic and adhering properties.
3.The paint film thickne ss shall not be less than 1.5 mils (38 m).
4.After drying, the finish shall not crack or chip from the metal when struck a light blow with a hammer.
5.The paint coating shall show no appreciable change in adhesion or appearance when immersed in water at room temperature for a period of 72 hours.
e.Galvanized posts shall be ho t-dip galvanized after fabrication in accordance with ASTM A 123.
f.Painted posts which have been heavily scratched or marred in shipment and galvanized posts which have their galvanizing damaged shall be rejected.
g.(1) Light-duty post shall be at least 2 inches (50 mm) and not more than 2 1/2 inches (38 mm) wide on the side of the post to which the sign is to be fastened.
2.The post's weight shall be at least 1.12 lb/ft (1.6 kg/m), and the post shall have at least 15 and not more than 20 holes.
3.Light-duty posts shall be painted black or dark green.
h.(1) Heavy-duty posts shall be at least 3 inches (75 mm) and not more than 3 1/2 inches (90 mm) wide on the side of the post to which the sign is to be fastened.
2.The post's weight sha ll not be less than 2.5 lb/ft (3.75 kg/m), and the post shall have at leas t 50 and not more than 60 holes.
Source: Nebraska Standard Specifications for Highway Construction, 2017 Edition. Pages 954–956 of 1,048.