- 221 - SECTION 417 -- HIGHWAY SIGNS
417.01 Description
1.This work shall consist of all materials and labor necessary to provide, fabricate, and install highwa y signs at the locations shown in the contract.
417.02 Material Requirements
1.Materials for highway signs shall conform to the requirements of Section 1070 and the current adopted version of the Manual on Uniform Traffic Control Devices for Streets and Highways .
a."Type A Signs" are regulatory, warning, guide, and information signs composed of a flat aluminum sheet background surfaced with retroreflective sheeting and the message either directly applied or reverse screened on the sign face, all in the colors specified in the contract. Bridge and hazard markers shall be classified as a Type A sign.
b."Type B Signs" are large guide and information signs mounted along the roadside or on overhead structures and constructed of molded extruded panels or reinforced aluminum, horizontally joined panels with retroreflective sign sheeting and direct applied letters, numerals, symbols, and borders.
c.“Type C Signs” are large guide and information signs mounted on overhead structures and construc ted of molded extruded panels or reinforced aluminum, horizontally joined panels sheeted with retroreflective sign sheeting and direct applied letters , numerals, symbols, and borders.
2.Mounting:
a."Type A Signs" shall be mounted on breakaway posts made from aluminum, steel, or wood as indicated in the contract.
b.Type B ground mounted signs shall be mounted along the roadside as shown in the contract and supported by structural steel beam breakaway posts with the post stub extending into round, reinforced concrete footings.
c.Type B and C overhead signs shall be mounted over the roadway on sign structures, including cantilever structures, with vertical supports installed on reinforced concrete foundations or on sign brackets attached to existing roadway bridges.
3.Retroreflective sheeting for Type A and B signs shall meet the requirements of ASTM D 4956 Type IV.
4.Retroreflective sheeting for Type C signs shall meet the requirements of ASTM D 4956 Type XI.
5.All concrete shall be Class 47B-3000 conforming to the requirements of Section 1002.
6.Before fabrication, the Cont ractor shall prepare and submit complete design drawings for Type B and C signs for approval. These shall include 6 sets of prints and drawings on half size plan sheets (11 x 17 inches [297 x 420 mm]) prepared and signed by a registered Professional Engineer licensed in Nebraska.
417.03 Highway Signs
- 222 - 417.03 -- Construction Methods
1.The Contractor shall prepare t he sheet aluminum for retroreflective sheeting on both Type A, B, and C signs as follows:
a.Paint shall be removed with lacquer thinner or a controlled alkaline cleaning system.
b.The aluminum sheet and extr usheet panels shall be degreased by one of the following methods:
1.Vapor Degreasing--Total immersion of the sign in a saturated vapor of trichlorethylene or perchlorethylene.
2.Alkaline Degreasing--Signs shall be immersed in a tank containing alkaline solutions, controlled and titrated to the solution manufacturer's specifications. Immersi on time shall depend upon the amount of soil present. Metal shall be rinsed thoroughly with running water.
c.Acid Etching:
1.The aluminum sheet and extrusheet panels shall be acid etched in a 6 to 8% phosphoric acid etching solution at 100°F (38 C).
2.After etching, the metal shall be thoroughly rinsed with running cold water.
3.The cold rinse shall be followed by a hot water rinse. A forced hot air drier shall be used to dry the panels.
d.Metal shall not be handled directly, but shall be moved with a mechanical device or clean canvas gloves between all cleaning and etching operations and the application of reflective sheeting. There shall be no opportunity for metal to contact greases, oils, or other contaminants before the appl ication of reflective sheeting.
2.Reflective Sheeting Application: a. Reflective sheeting shall be mechanically applied to properly treated base panels using the sheet ing manufacturer's recommended procedures and equipment.
b.Seams:
1.The Contractor shall apply the reflective sheeting without visible seams or joints.
2.If seams are required, they must be carefully matched for color at the time of sign fabrication to provide uniform appearance and brilliance, both day and night.
3.Signs on which the background color of adjacent sheets or panels is not properly matched will be rejected.
c.After aging 48 hours at 75°F (24 C), adhesion of retroreflective sheeting to the sign surface shall be strong enough to resist stripping from the panel when tested with a stiff putty knife. Highway Signs 417.03 - 223 - 3. The message, legend, and border of Type A signs shall be applied by one of two processes, depending on the kind of sign.
a.Direct Screen:
1.Direct screened processing shall consist of processing the message, legend, and border color on the face of the sign by the silk screen process.
2.The color material to be used and the dry film thickness to be obtained shall be as recommended by the manufacturer of the reflective sheeting.
3.The color of the sign face, message, legend, and border shall be as shown in the contract.
b.Reverse Screen Process:
1.Reverse screen processing shall consist of processing an opaque or transparent color over the sign face to form the legend and border.
2.The opaque or transparent process color material to be used and the dry film thickness to be obtained shall be as recommended by the manufacturer of the reflective sheeting.
3.The color of the sign face, legend, and border shall be as shown in the contract.
4.Extrusheet Panels:
a.The extrusheet panels for eac h sign shall be of the length and width specified in the contract.
b.The width of the top, intermediate, and bottom panels shall be in the sequence shown in the contract for each sign.
c.There shall be no longitudinal gap between panel joints on the sign face, and the face of the panels shall be in the same plane on the sign face.
d.The ends of all panels in any one sign shall be perpendicular and in line. The ends shall be free from burrs.
e.The surface of all sign pane ls shall be flat and free of flaws.
f.The sign shall be attached to vertical supports as shown in the contract.
g.The vertical supports shall be flush with the top of the sign.
5.Type B Sign Legends:
a.Letters, numerals, symbols, and border for Type B signs shall be directly applied.
b.Large letters, numerals, and symbols may be fastened to the panel face with self-plugging type rivets, 1/8 inch (3 mm) in diameter and of all aluminum construction, when they cannot be directly applied.
1.Rivet length shall be as recommended by the manufacturer for the combined thickness of each legend material and the structural panels to which they are applied.
417.03 Highway Signs
- 224 - (2) After a rivet is set, the st em, if remaining, shall be trimmed flush with the rivet head in a manner recommended by the rivet manufacturer.
6.Height of all signs shall be as shown in the contract.
7.The Engineer will upon request establish by stake (or mark on the pavement) the location of each sign and will also establish the elevation of the edge of the roadway if it does not exist.
b.Sign Offsets: (1) In urban areas signs shall be mounted so that any edge of the sign which is adjacent to a roadwa y will be 2 feet (600 mm) outside of the curb where there is a barrier type curb.
2.On rural freeways (inter state), the edge of any sign shall be at least 35 feet (10.7 m) from the edge of the r oadway, excluding exit gore signs.
3.On rural expressways, the edge of any sign shall be at least 30 feet (9.1 m) from the edge of the roadway, excluding exit gore signs.
4.On urban freeways or expressways, the edge of any sign shall be at least 30 feet (9.1 m) from t he edge of the roadway, excluding exit gore signs.
8.Type B and C signs shall be erected so that the sign face is vertical and positioned as shown in the contract. On curved alignments, the angle of placement should be determined by the course of approaching traffic rather than by the roadway edge at the point where the sign is located.
9.Sign Fasteners:
a.Type A signs shall be fastened to sign posts with threaded bolts as described in Section 1071.
b.Type B and C signs shall be fastened to the supports in accordance with the recommendations of the extrusheet panel manufacturer. All supports shall be cu t off flush with the top of the sign.
10.Breakaway Posts:
a.The Contractor shall drill w ood posts as shown in the contract to provide a breakaway feature.
b.Steel Posts: (1) The Contractor shall fabricate steel beam breakaway posts in accordance with Section 708.
2.Mill test reports shall be submitted to the Engineer before fabrication.
3.The saw cut for the breakaway hinge should be made on the job site to avoid deformation of the pre-cut post in shipping.
4.The saw cut shall be free of galvanizing material. (5) The saw cut and any damage to galvanizing shall be repaired in accordance with Method 2 of Section 1061.
6.Any deformation of the post shall be cause for rejecting the post. Highway Signs 417.04 - 225 - (7) The fuse plate bolt shall be tightened by the turn-of-the-nut method described in Subsection 708.03. The base connection assembly shall follow the procedure outlined in the contract which shall include rechecking the torques until all bolts in the base have the described torque. This procedure shall be repeated immedi ately preceding the final inspection of the project.
8.Footings for roadside mounted signs on steel beam breakaway posts shall be concrete.
i.The footing shall be circular in shape and of the diameter and depth shown in the contract. (ii) Before placing concrete footings, stub posts shall be placed so the posts are plumb and correctly spaced. (iii) Footings shall be no higher than 4 inches (100 mm) above the ground to prevent snagging. (iv) Footing construction shall be in accordance with the applicable requirements of Se ctions 702, 704, and 707.
11.When 2 or more signs are required on an overhead sign support, the bottom of all signs shall have the same elevation so they will be horizontally aligned with each other. All signs shall be hung at a minimum of 2 feet (600 mm) above the sign support walkway. Sign posts and vertical supports used as sign stiffeners shall be cut off flush with the top of the sign.
417.04 Method of Measurement
1.Providing, fabricat ing, and installing Types A, B, and C signs shall be measured by the square foot (m2).
2.Providing and installing breakaway steel supports for Type A and Type B signs shall be measured by the pound (Kg) of unplated, unwelded, and undrilled steel. The pounds (Kg) of st eel shall be the weight per foot (m) multiplied by the length of sign s upport above the stub post required at each location. Connection shall be subsidiary to this item.
3.Providing, fabricat ing, and installing wood supports for Type A and Type B signs shall be measured for payment by the linear foot (meter). The quantity to be paid for shall be the actual support length used or as ordered by the Engineer.
4.Providing and constructing conc rete footings for a steel beam breakaway post for Type A and B signs will be measured by the each for each post.
417.05 Highway Signs
- 226 - 417.05 -- Basis of Payment
1.Pay Item Pay Unit Type A Sign Square Foot (SF) [Square Meter (m2)] Type B Sign Square Foot (SF) [Square Meter (m2)] Type C Sign Square Foot (SF) [Square Meter (m2)] Install Type A Sign Square Foot (SF) [Square Meter (m2)] Install Type B Sign Square Foot (SF) [Square Meter (m2)] Install Type C Sign Square Foot (SF) [Square Meter (m2)] Structural Steel for Sign Suppo rts Pound (lb) [Kilogram (kg)] 4 x 4 Inch Wood Sign Support Linear Foot (LF) [Meter (m)] 4 x 6 Inch Wood Sign Support Linear Foot (LF) [Meter (m)] _____ Sign Support Footing Each (ea) 2. Furnishing and installing 40 inch (1 m) long stub posts and the required reinforcing steel shall be subsidiary to the "_____ Sign Support Footing".
3.Connecting and mounting hardware shall be subsidiary to the relevant pay item.
4.Payment is full compensation for all work described in this Section. - 227 - SECTION 418 -- OVERHEAD SIGN SUPPORTS
418.01 Description
1.a. "Overhead Sign Support, Location _____" shall consist of:
1.Providing all materials to construct overhead sign supports.
2.Transporting all sign support materials to the project site. (3) Constructing all trusses and other sign support structures as shown in the contract (including attachment of sign brackets to the structure).
4.Providing the Department copies of the manufacturer's designs of the overhead sign support structure. Steel cantilever and steel truss or aluminum box truss structures shall be manufacturer-designed. Bridge brackets shall comply with the design provided in the contract.
5.(i) Providing the design for the concrete foundation for the sign support. (ii) The foundation shall be continuous between the vertical end supports of the sign struct ure when the foundation is located in the median and will requir e impact attenuators. (iii) Foundation design shal l be based on test results of soil borings taken from the location of each overhead sign support. Soil borings, soil analysis, and foundation design must be performed by individuals proficient in that line of work. (iv) The Contractor shall submit two (2) complete Geotechnical Engineering Reports showin g the soil analysis of the borings taken at each of the sign support locations, eight (8) complete 1/2 size sets of plans of the foundation design drawings, and eight (8) complete sets of reports on the foundation design computat ions to the Engineer for review.
v.The foundation design drawings and computations must be signed and stamped by a regist ered Professional Engineer licensed in Nebraska. Acceptance of the foundat ion design(s) by the Department will be based upon this seal and signature.
b.Aluminum or steel trusses that span multi-lane roadways and when shown in the contract, shall be provided with a sign lighting system in accordance with Sections 401 through 412.
c.Steel cantilevers shall be in stalled at the si de of the roadway with the horizontal member overhanging the roadway and shoulder.
d.Steel sign brackets shall be attached to existing roadway bridges spanning the roadway and when shown in the contract, shall be provided with a sign lighting system in accordance with Sections 401 through 412.
e.Plans shall be augmented by Contractor-furnished working drawings submitted in accordance with Subsection 105.02.
2.Full Span and Cantilever Sign Structures: a. The overhead sign supports shall be steel or aluminum box or single panel truss structures.
Source: Nebraska Standard Specifications for Highway Construction, 2017 Edition. Pages 255–260 of 1,048.