- 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.
418.01 Overhead Sign Supports
- 228 - b. The work shall consist of des igning, furnishing, and erecting a structure, complete with vertical end supports, span members, walkways, sign brackets, foundations, and all necessary material and fasteners for assembling the structures. All material fabrications shall be in accordance with the applicable requirements of Se ctions 401 through 412, 417, 708, and 1040.
c.All overhead sign support stru ctures shall be fabricated in a plant owned and operated by a fabricator sufficiently experienced to manufacture the structures in accor dance with these Specifications. The Contractor shall furnish the name and ad dress of the fabricator, if requested by the Engineer, and evidence of t he fabricator's qua lifications and experience.
418.02 Material Requirements
1.Aluminum cantilevers, trusses, and other sign supports shall be made from the alloys in Table 418.01 and shall conform to the indicated ASTM requirements.
2.Steel sign supports for Type B and C (See Section 417 for type definitions) signs shall be fabricated from structural steel conforming to the requirements of ASTM A 36/A 36M with a maximum working stress of 20,000 psi (140 MPa). After fabricati on, the cantilever members shall be galvanized in accordance with ASTM A 123. Table 418.01 Alloy Requirements Member or Shape Aluminum Alloy ASTM Requirements Extruded tubes for chord and column members 6061-T6 B211/B 211M; B Bracing Members 6063-T6 B221/B 221M; B Extruded Shapes 6061-T6 B211/B 221M; B 308/B 308M Plates 6061-T6 B209/B 209M Post Base and Chord Flange 356.0-T6 Aluminum Alloy Sand Castings 356.0-T6 B26/B26M Aluminum Alloy Permanent Mold Castings 356.0-T6 B 108 Grates 6061-T6 B211/B 211M; B221/B221M Bearing Bars 6061-T6 B211/B 211M; B221/B221M Cross or Crimp Bars 6063-T5 B211/B 211M; B221/B221M Pipe Handrail 6061-T6/6063-T6 B 221M; B 241/B 241M Post and Chord Caps 356.0-F B 26/B 26M Anchor Bolts & Nuts --- A 325 Galvanizing --- A 153 Overhead Sign Supports 418.02 - 229 - 3. Steel sign brackets to be attached to existing bridges shall be fabricated from structural steel conforming to ASTM A 36/A 36M with a maximum working stress of 20,000 psi (140 MPa).
4.Concrete Foundations:
a.The reinforced concrete foundations shall be constructed to the dimensions shown in the shop plans.
b.The materials and construction methods shall be in accordance with the applicable requirem ents of Sections 702, 704, and 707 and as required in the shop plans.
5.Anchor Bolts for Sign Supports: a. The structure manufacture r shall design and furnish all required anchor bolts (as specified below). Each anchor bolt shall be provided with seven (7) heavy hex nuts and two hardened steel flat washers.
1.The Contractor shall furnish an extra bolt sample (including nuts and washers) from each he at of steel used on the project (or multiple projects) to the Materials and Research Division for destructive testing.
2.Anchor bolts shall be straight rods threaded a minimum of 24 inches on the top end and a minimum of 24 inches on the bottom end. The threads of all anchor bolts must be rolled in accordance with standard industry practice.
3.The use of cut threads will not be permitted. Galvanizing the anchor bolts and heavy hex nuts will not be allowed. Prior to shipment, the top 24 inches of the anchor bolt together with its heavy hex nuts and hardened flat washers shall be cleaned and painted with zinc rich paint to a minimum dry film thickness of 4 mils. The type of zinc rich paint and its method of application will be approved by the Department.
4.The minimum foundation design acceptable for cantilever sign structures will be one detailing six (6) – 2 inch (50 mm) diameter anchor bolts (designed for fatigue) of AASHTO M-314, Grade 55 or equivalent steel.
5.The minimum foundation design acceptable for overhead sign support structures will be one detailing four (4) – 2 inch (50 mm) diameter anchor bolts (4 for each support, designed for fatigue) of AASHTO M-314, Grade 55 or equivalent steel.
6.Regarding Overhead Span and Cantilever Sign Structures, the Contractor’s actual design may require a greater number of anchor bolts, anchor bolts of larger diam eter or both. In all cases, however, anchor bolts must meet AASHTO M-314, Grade 55 or equivalent steel.
7.The design shall allow sufficient space between the shaft supports and the anchor bolts (and/or bet ween the hand hole opening flange and the anchor bolts), to allow the use of deep well sockets which are required when performing proper tensioning of the anchor bolt nuts in accordance with NDOT Specifications.
b.The heavy hex nuts shall me et the requirements of ASTM A- 563 Grade C3 or DH3.
c.The plain hardened steel washers shall conform to the requirements of ASTM F 436 Type 3 or ASTM F 436M Type 3. If Type 3
418.02 Overhead Sign Supports
- 230 - plain hardened steel washers are not available for the specified bolt diameter, mechanically deposited zi nc coated hardened steel washers conforming to the requirements of ASTM F 436 or ASTM F 436M shall be used. Only flat washers shall be used. The use of lock washers will not be permitted.
d.Anchor bolts of the specif ied size for each support shall be supplied in an assembly retained with steel templates (conforming to the requirements of ASTM A 36/A 36M) and nuts (see plan detail) to prevent their movement while the concrete f ooting is being poured to ensure proper bolt spacings and alignment. Welding on anchor bolts will not be permitted. This assembly shall be detailed on the shop plans. The anchor assembly cage shall be placed at the depth shown in the shop plans, properly aligned and secured in place before placing concrete. Once the concrete has set, no adjustments or realignments shall be made to the anchor bolts. Field straightening of anchor bolts will not be allowed. The anchor bolts shall be truly vertical, with no more than a 1/8 inch deviation in 12 inches (3 mm in 300 mm) of length permitted. Anchor bolt projection above the base plate shall allow for the thickness of a hardened flat washer, for the capture of two heavy hex nuts plus 1/2 inch, while allowing no more than two anchor bolt diameters between the top of the conc rete foundation and the bottom of the base plate.
e.The manufacturer of the anchor bolts shall furnish certification and test reports covering the steel used. The test report shall show the following:
1.Chemical analysis of the steel used. (2) Yield strength in pounds per square inch (MPa). (3) Tensile strength in pounds per square inch (MPa). (4) Percent elongati on in 2 inches (50 mm).
5.Percent reduction in area.
6.Overhead Span and Cantilever Sign Design Requirements: a. (1) The overhead span and cant ilever sign structures shall be box or single panel trusses designed in accordance with the latest edition of the Specifications for the Design and Cons truction of Structural Supports for Highway Signs , published by the American A ssociation of State Highway Transportation Officials.
2.All overhead structures shall be designed to be supported by single poles or end frames having no more than 2 vertical main members of a closed cross section.
3.The sign spans, sign locations, and sign mounting heights used for structure calculations sha ll be as shown in the contract.
4.The design areas used for calculations shall be the sign areas shown plus 30% or as noted on the contract.
b.Overhead Span Materials:
1.Designs, materials, and basic member shape, once selected, shall be used throughout the project. Overhead Sign Supports 418.02 - 231 - (2) Overhead Truss Structur es shall be aluminum or steel galvanized after fabrication. Cantilev er Structures shall be of galvanized steel.
c.Footings shall be reinforced concrete with the overhead portion of the structure attached by means of base plates and anchor bolts. The top of each footing shall extend 12 inches (300 mm) above ground level and shall have a 1 inch (25 mm) chamfer on its edges. Footings shall be constructed so that the top surface shall be level [less than 1/4 inch in 3 feet] (6 mm in 900 mm).
d.Footing Design:
1.The contractor shall design a concrete foundation showing foundation dimensions, reinforcement an d anchor bolts for each of the sign structure locations requiring a new fo undation. Foundation design shall be based on test results of soil borings ta ken from the areas of each of the new sign structure locations. Soil borings, soil analysis and foundation design shall be performed by individuals pr oficient in that line of work.
2.The contractor shall submit two complete Geotechnical Engineering Reports showing the soil analysis of the borings taken at each of the sign structure locations: six complete half-size sets of foundation design drawings together with two complete sets of foundation design computations to the traffic engineer for review.
3.The foundation design draw ings and computation shall be signed and stamped by a registered professional engineer, licensed in Nebraska. Acceptance by the State of the foundation design(s) will be based upon this seal and signature. By applying his/her seal and signature to the design drawing and calculations, the engineer affirms that the foundations are of proper design and material to m eet the structural requirements of the specifications.
4.The minimum foundations design acceptable will be as specified in Paragraph 6 of Subsection 418.02.
5.Each structure sign footin g shall be neatly excavated to its design dimensions; only the top two feet (600 mm) may be formed. The excavation shall be dry with all loose material removed before concrete can be placed.
e.The bottom of aluminum supp orting shafts and all anchor bolts shall receive a heavy coating of alumin um filled, resilien t sealing compound completely covering all areas which may contact the concrete. The sealing compound shall be on the Department’s Approved Products List .
f.Corrosion of aluminum caused by contact with dissimilar metals shall be prevented by proper design considerations and installation procedures.
g.Full Span structures shall be lighted with walkways provided in front of and in back of the entir e length of the structure.
1.Sign lighting and electrical equipment for the structure shall be in accordance with the applicable requirements of Sections 401 to 413 and 1073.
418.02 Overhead Sign Supports
- 232 - (2) The walkways shall be continuous to the vertical access point/support and shall be a minimum of 3 feet in width.
3.Walkways shall have a railing along the front side which can be folded when not in use. The fold-down handrails shall be limited to sections that are 12 feet (4 m) or less in length.
4.No part of a walkway or railing in the folded position shall obstruct normal viewing of the sign.
h.Cantilever structures sha ll be lighted and have front and back walkways, continuous over the width of the sign and shoulder and extending to the vertical end support. These walkways shall be at the same level +/- 6 inches (150 mm).
1.Both front and back walkways (closest to cantilever arm) shall extend a minimum of 2 feet (600 mm) beyond the sign's vertical edge.
2.Vertical deflection of the cantilever arm shall be limited to L/120.
i.Vertical sign supports for overhead signs shall be constructed independently of the overhead sign stru cture and/or walkways to allow for future signing changes on the overhead sign structure.
j.For access to the walkway, a ladder or other type of foot support shall be constructed on the end support beginning 9 feet (3 m) above the ground.
k.Connecting bolts on structures will be ASTM A 325 Type I, galvanized.
l.Before fabrication, the C ontractor shall prepare and submit complete design drawings, calculations, and other supporting data for approval. These shall include 6 sets of prints and drawings on half size plan sheets (11 x 17 inches [297 x 420 mm]) and 2 sets of design computations prepared and signed by a registered Professional Engineer licensed in Nebraska.
418.03 Construction Methods
1.General:
a.The Contractor shall take precautions to avoid scarring or marring aluminum or galvanized surfac es. Any such damage which, in the judgment of the Engineer, gives an obje ctionable appearance or contributes to weakening of the structure will be cause for rejection.
b.The Contractor shall remove all casting irregularities from cast parts.
c.Tubing shall be seamless; and exterior and interior surfaces shall be clean, smooth, and free from slivers, lamination, grooves, cracks, or other defects.
d.Poor welding skill, as noted by visual inspection, will be sufficient cause for rejection. Overhead Sign Supports 418.03 - 233 - 2. Fabrication of Sign Structures:
a.Aluminum alloy fabrication shall conform to AWS procedures and the following:
1.Thermal cutting will not be allowed. (2) Material 1/2 inch (12. 5 mm) or less in thickness may be sheared, sawed, or milled. Material over 1/2 inch (12.5 mm) in thickness shall be sawed or milled. Cut edges shall be true and free from excessive burrs or ragged breaks.
3.Material to be bent may be heated to a temperature not exceeding 400°F (205°C) for a period not exceeding 15 minutes to facilitate bending.
4.Bolt holes shall be drilled full size or subpunched 1/8 inch (3 mm) smaller than the nominal diameter of the fastener and reamed to size. Unless otherwise indicated in the c ontract, the finished diameter of the holes shall be not more than 7% greater than the nominal diameter of the fastener.
5.The length of the vertical end frames for structures shall be field checked before fabrication.
b.Fabrication of steel materi als (center mounts, cantilevers, and sign brackets) shall be in accordance with the applicable requirements of Section 708. Center mount and cantilever structures shall be galvanized as required by the contract. Sign brackets shall be painted in accordance with the applicable requirements of Section 709 and as required by the contract.
3.Aluminum Welding Requirements: a. (1) The aluminum alloys shall be welded in accordance with the ASTM requirements listed below: Wrought heat-treatable alloys Alloy 6061 Alloy 6063 Cast heat-treatable alloy Alloy 356.0
2.Material used for permanent backing shall be at least equivalent in weldability to the base metal being welded.
3.These Specifications include provisions for welding by the gas metal-arc process and the gas tungsten-arc process.
4.Bare wire electrodes for use with the gas metal-arc process and welding rods for use with the gas tungsten-arc process shall conform to the requirements of Specifications for Aluminum and Aluminum- Alloy Welding Rods and Bare Electrodes, AWS A5.10.
5.Tungsten for the gas t ungsten-arc process shall conform to the requirements of Specifications for Tungsten-Arc Welding Electrodes , AWS A5.12. Filler metals to be used with particular base metals shall be as shown in Table 418.02. Other filler metals may be used as approved by the Engineer.
418.03 Overhead Sign Supports
- 234 - Table 418.02 Filler Metal Requirements AWS Base Metal Use Filler Metal 6061 welded to 6063 ER5356 6063 welded to 6063 ER5356 356.0 welded to 6061 ER4043 356.0 welded to 6063 ER4043
6.(i) Filler metals shall be kept covered and stored in a dry place at relatively uniform temperatures. (ii) Original rod or wire containers shall not be opened until time to be used. (iii) Rod and wire shall be free of moisture, lubricant, or other contaminants. (iv) Spools of wire temporarily left unused on the welding machine shall be kept covered to av oid dirt and grease contamination.
v.If a spool of wire is to be unused for more than a short length of time, it shall be returned to the carton and the carton tightly resealed.
7.(i) Shielding gases shall be welding grade or better. Shielding gas for gas metal-arc shall be argon, helium, or a mixture of the two (approximately 75% helium and 25% argon). (ii) Shielding gas for gas tungsten-arc welding done with alternating current shall be argon. (iii) Shielding gas for gas tungsten-arc welding done with direct current, straight polarity, shall be helium. (iv) Hose used for shielding gases shall be made of synthetic rubber or plastic.
v.Natural rubber hose shall not be used. Hose which has been previously used for acetylene or other gases shall not be used.
b.(1) (i) Joint details shall be in accordance with design requirements and detail drawings. (ii) The location of joints shall not be changed without the approval of the Engineer. (iii) Edge preparation shall be by sawing, machining, clipping, or shearing. Gas tungsten-arc or gas metal-arc cutting may also be used. (iv) Cut surfaces shall meet the American Standards Association surface roughness rating value of 1,000.
v.Oxygen fins, tears, and other defects which would adversely affect the quality of the weld will not be allowed. (vi) Dirt, grease, lubricants, or any organic materials shall be removed from the areas to be welded by cleaning with a suitable solvent or by vapor degreasing. Overhead Sign Supports 418.03 - 235 - (vii) On all edges and surfaces to be welded, the oxide shall be removed just before welding by wire brushing or by other mechanical methods such as rubbing with steel wool or abrasive cloth scraping, filing, rotary planing, or sanding. If a wire brush is used, the brush shall be made of stainless steel.
2.Hand or power driven wire brushes which have been used on other materials shall not be used on aluminum.
3.(i) Where mechanical methods of oxide removal are found to be inadequate, a standard chemical method shall be used. (ii) Chemical removal of aluminum oxide shall be accomplished by one of the chemical treatments recommended in the AWS or the Aluminum Association Welding Aluminum pamphlet. (iii) Welding shall be done within 24 hours after chemical treatment. (iv) When gas tungsten-ar c welding with direct current, straight polarity, is being used, all edges and surfaces to be welded shall have the oxide removed by a standard chemical method.
v.Welding shall not be done on anodically treated aluminum unless the condition is removed from the joint area to be welded.
4.(i) All butt welds requiring 100% penetration, except those produced with the aid of backing, sh all have the root of the initial weld chipped or machined out to sound metal before welding is started from the second side. (ii) Butt welds made with the use of backing shall have the weld metal thoroughly fused with the backing. (iii) Where accessible, backing for welds that are subject to computed stress or which are expos ed to view on the completed structure and which are not otherwise parts of t he structure shall be removed and the joints ground or machined smooth. (iv) In tubular members, butt welds subjected to computed stresses shall be made with the aid of permanent backing rings or strips.
5.The procedure used for production welding of any particular joint shall be the same as t hat used in the proc edure qualification for that joint.
6.Undercut shall not be more than 0.01 inch (0.25 mm) deep when its direction is transverse to t he primary stress in the part that is undercut. Undercut shall not be more than 1/32 inch (0.8 mm) deep when its direction is parallel to the primar y stress in the part that is undercut.
7.No overlap shall be allowed. (8) All craters shall be filled to the full cross section of the welds.
9.Welds having defects greater than the levels of acceptance specified above shall be considered as rejected unless corrected as indicated below.
418.03 Overhead Sign Supports
- 236 - (10) All welding operations, either shop or field, shall be protected from air currents or drafts to prevent any loss of gas shielding during welding. Adequate gas shielding shall be provided to protect the molten metal during solidification.
11.The work shall be positioned for flat position welding whenever practicable.
12.In both the shop and field, all weld joints shall be dry at the time of welding.
13.The size of the elec trode, voltage, amperage, welding speed, gas or gas mixture, and gas fl ow rate shall be suitable for the thickness of the material, design of joint, welding position, and other circumstances attending the work.
14.Gas metal-arc welding shall be done with direct current, reverse polarity.
15.Gas tungsten-arc welding shall be done with alternating current or with direct cu rrent, straight polarity.
16.(i) When the joint to be welded requires specific root penetration, the Contractor shall make a sample joint and a macroetched cross section of the weld to demonstra te that the joint welding procedure used will attain the required root penetration. (ii) The sample joint shall have a length of at least 1 foot (300 mm) and shall be welded with the electrode, polarity, amperage, voltage, speed, gas mixture, and gas fl ow rate that are proposed to be used in production welding. (iii) Tolerance for variation of amperage and voltage shall be plus or minus 10% for amperage and plus or minus 7% for voltage during fabrication. (iv) The Engineer, at his/her discretion, may accept evidence on record in lieu of the preceding test.
17.Where preheating is needed, the preheating temperature shall not exceed 350°F (177°C) for heat-treated alloys and 600°F (315°C) for non-heat-treated alloys. The temperature shall be measured by temperature indicating crayons or by pyrometric equipment. Heat treated alloys shall not be held at the maximum preheat temperat ure or at temperatures near the maximum for more than 30 minutes.
c.Weld Quality:
1.Regardless of the method of inspection, the acceptance or rejection of welds shall be determined by the following conditions:
i.Cracks in welds or adjacent base metal are not acceptable. (ii) Copper inclusion is not acceptable. (iii) Porosity in excess of that allowed by Appendix IV, Section VIII of the ASME Boiler and Pressure Vessel Code will not be acceptable. (iv) Lack of fusion, incomplete penetration, or tungsten or oxide inclusions are acceptable only if small and well dispersed. Overhead Sign Supports 418.03 - 237 - (2) For highway sign structures, the dye penetrant method shall be used on butt welds in columns, main chord members, and on fillet welds connecting columns to bases and main chord members, including the associated flanges, gussets, or main load carrying brackets or members. This method shall also be used on fillet welds connecting flanges to the main truss chord members.
3.The dye penetrant tests shall be performed in accordance with the requirements of ASTM E 165, Standard Methods for Liquid Penetrant Inspection, Method B.
4.Dye penetrant inspection may be omitted if the Inspector examines each layer of weld metal with a magnifier (3X power minimum) before the next successive layer is deposited.
5.Dye penetrant inspection will be required and performed at the Contractor's expense. Personnel performing liquid penetrant inspections shall be qualified as required in AWS. In all cases where the dye penetrant method is done by the Contractor, t he inspector must be present when the inspection is made.
d.(1) The Contractor may make the corrections shown in Table 418.03 when a weld is defective. These corrective measures shall be approved by the Engineer before work begins. Table 418.03 Welding Defects Problem Corrective Action Defective weld Remove and replace the entire weld. Cracks in weld or base metal Determine full extent of crack by dye penetrant method of other positive means. Remove crack throughout its length and depth and reweld. Excessive porosity, lack of fusion Remove defective portions and reweld. Copper or tungsten inclusion Remove defective portions and reweld. Excessive concavity of crater, undercut, undersize weld Clean and deposit additional weld metal. Overlap Reduce by removal of excess weld metal.
2.The Contractor shall remove the defective areas by chipping or machining. Oxygen cutting shall not be used. Before rewelding, the joint shall be inspected to assure that all of the defective weld has been removed. If dye penetrant has been used to inspect the weld, all traces of penetrant solutions shall be removed with solvent, water, heat, or other suitable means before rewelding.
e.Qualification of Procedures, Welders, and Welding Operators:
1.Joint welding procedures which are to be employed in executing contract work under these Specifications shall be previously
418.03 Overhead Sign Supports
- 238 - qualified by tests described in Part B, Section IV, of the ASME Boiler and Pressure Vessel Code. The qualifications shall be at no additional cost to the Department. The Engineer, at his/her discretion, may accept evidence of previous qualifications of the joint welding procedures to be employed.
2.All welders and welding operators to be employed under these Specifications shall be previous ly qualified by tests as described in Part V, Section IX, of the ASME Boiler and Pressure Vessel Code. The Engineer, at his/her discretion, may accept evidence of previous qualification of the welders and welding operators to be employed. The same process and type of equipment that is required for execution of the construction work shall be used in qualifying welders and welding operators.
f.Steel welding shall be in accordance with Section 708. 4. Inspection of Single Panel or Box Truss Sign Structures: a. The Contractor shall inspect single panel and box trusses in accordance with Section 708. All mill te st reports and certifications shall be furnished to the Engineer before any requests for shop inspection are made.
b.To determine compliance with these welding procedures, all welds shall be visually inspected and a random sample of welds shall be chosen by the inspector to be investigated using dye penetrants.
5.Fastening to Supports:
a.In fastening a sign to the sup ports, the Contractor shall follow the recommendations of the manufactu rer of the extrusheet panels as to frequency of post clamps and torque on nuts.
b.The Contractor shall exercise care in handling and erecting signs so damage is prevented. The Cont ractor shall replace at no additional cost to the Department any sign which is damaged before final project acceptance.
6.Field Installation of Sign Structures:
a.The Engineer or his designat ed representative shall be present at all times during pole installation. T he Contractor shall notify the Materials and Research Division and Traffic Engineering Division to arrange for inspection no less than 3 days prior to pole installation. No poles installed without proper inspection will be acce pted by the state for final payment.
b.Proper Tensioning of Si gn Structure Anchor Bolts and Connecting Bolts In order to provide the corr ect tension to anchor bolts, the Contractor will be required to hav e on hand the following items:
1.A standard combination wrench (box end/open end) 24 inches in length for snug tightening of bolts less than 1 ¾” diameter and a Standard Combination wrench 36 inches in length for bolts equal to or greater than 1 ¾” diameter.
2.A deep well impact socket for final tightening, for each size nut being installed. Overhead Sign Supports 418.03 - 239 - (3) A torque multiplier (plate reaction style) with the following minimum requirements: Gear Ratio: 60:1 Torque Ratio: 52:1 Output Capacity: 8000 ft.-lb. Anchor bolt hold-down nuts and connecting bolt nuts shall be tightened by the turn-of-the-nut method as described below, but only after determining that the le veling nut/flat hardened washers for the anchor bolt are in full contact with the underside of a level base plate. Turn-of-the-Nut Method (a) Snug tighten and final tighten all nuts in a “star” pattern.
b.Using the appropriate combination wrench, apply full effort of a workman to the end of the wrench to “snug tighten” the nut.
c.Mark the location of one corner of the nut on the base plate.
d.Using the torque multiplier and the mark placed on the base plate; for nuts that are equal to or greater than 1 ¾”, tighten the nut onto the anchor bolt by giving the nut 1/6t h of a turn (this is equal to turning the nut onto the anchor bolt a distance equal to the length of one flat or until the next corner of the nut is even with the mark on the base plate). For nuts less than 1 ¾” diameter, use a 1/3rd of a turn.
e.Install a “lock nut” or “jam nut” on each of the anchor bolts by repeating steps (a) through (c).
f.After the top nuts are fully tightened, all leveling nuts should be retightened to assure that full contact has been maintained with the bottom of the base plate. Connecting bolt nuts shall be tightened by the same turn- of-the-nut method as described for anchor bolts with the exception that the bolt head must be held stationary while applying the torque multiplier. Nuts shall be rechecked for tightness by the Contractor no less than 14 days, nor more than 30 days following installation in the presence of the Engineer. After the structure has been checked, lock nuts shall be installed to keep the nuts from working loose.
c.The Contractor shall dress, as necessary to provide a proper seating of the bases, the areas of t he foundation concrete upon which the shafts are to be set before the erecti on of the aluminum vertical end supports. The bottoms of the supporting shafts and all anchor bolts shall receive a heavy coating of aluminum filled, resilient sealing compound, completely covering all areas of aluminum which may contact the concrete. The compound used shall be on the Department’s Approved Products List .
d.The Contractor shall assemble the truss sections in the field on the ground and adjust them with shims to provide the camber called for in the contract. While assembled, the tru ss shall be erected on the end frames in one piece.
e.The end supports shall be erected on the leveling nuts to a truly vertical position and then the t op nuts securely tightened to the plate.
418.03 Overhead Sign Supports
- 240 - The grout shall not be placed until the truss has been erected, adjusted, and bolted to final position. The final proj ection of the base plate above the concrete foundation shall be no greater than the thickness of two leveling nuts.
f.After the structure has b een erected and completed and all signs mounted, the area between the top of the foundation and the bottom of the anchor base plates of the vertical end supports shall be filled using a high strength, non-shrink, grout from the Approved Products List. The grouting shall be placed the same day that the uprights are installed on the foundation.
7.Overhead Sign Electrical Requirements:
a.Signs requiring electricity w ill be identified in the contract.
b.The luminaires shall be on the Department’s Approved Products List.
c.The sign lighting luminaires shall be mounted as shown in the contract and in accordance with the manufacturer's instructions.
d.The lamps shall be 150 watt high pressure sodium unless shown otherwise in the contract.
e.All conductors shall be copper and shall be installed in conduit. The feeder cable shall be a minimum No. 8 gauge diameter THWN with a 30 ampere circuit breaker at the servic e entrance. Each sign structure shall be controlled by a 15 ampere 2 pole NEMA 3R breaker at a location convenient for maintenance of the luminaires.
f.Each sign structure shall have a photoelectric control mounted near the sign. The relays for switching t he line current to the lighting fixtures shall be mounted near the circuit breaker or as directed by the Engineer. Separate photocells are not required when sign lighting is tied into the roadway lighting.
g.Structure electrical equipment and material, when required, shall be in accordance with the applicable requirements of Section 1073.
8.a. The Contractor shall prov ide manufacturer-designed steel or aluminum box-truss overhead sign supports or steel brackets attached to a roadway bridge for Type B and C signs.
b.The structures that will su pport the Type B and C signs shall be constructed in conformance with Se ctions 417, 702, 704, 707, and 708 and as described in the contract.
9.When two 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 walkway. Sign posts and vertical supports used as sign stiffeners shall be cut off flush with the top of the sign.
418.04 Method of Measurement
1.Overhead Sign Supports are measured by the Each.
2.The foundation design and geotec hnical work, including but not limited to borings, analysis, designs, and submittals of the required drawings Overhead Sign Supports 418.05 - 241 - and reports, will not be measured for payment, but shall be considered subsidiary to the item "Overhead Sign Support, Location _____”.
3.Concrete for overhead sign support foundations is measured by the cubic yard (CY).
4.Reinforcing steel for over head sign support foundations is measured by the pound (Ib).
418.05 Basis of Payment
1.Pay Item Pay Unit Overhead Sign Support, Location _____ Each (ea) Sign Structure Foundation Design, Each (ea) Location _____ Class _______ Concrete for Cubic Yard (CY) Sign Support Foundations [Cubic Meter (m3)] Reinforcing Steel for Pound (Ib) Sign Support Foundations [Kilograms (kg)] Concrete for Foundation Cubic Yard (CY) [ C u b i c M e t e r ( m3)] Reinforcing Steel Pounds (lbs) [ K i l o g r a m s ( k g ) ]
2.The anchor bolt and/or anchor bolt assemblies required for the overhead sign support shall not be paid for directly, but shall be considered subsidiary to "Overhead Sign Support, Location _____".
3.The sign structure grounding sy stem is subsidiary to the item “Reinforcing Steel”.
4.Excavation for foundations is s ubsidiary to the item “Sign Structure Foundation Design, Location _____".
5.Soil borings and soil analysis fo r the sign structure foundation is subsidiary to “Sign Structure Foundation Design, Location _____".
6.Payment is full compensation for all work described in this Section. - 242 - SECTION 419 -- TRAFFIC CONTROL MANAGEMENT AND SURVEILLANCE
419.01 Description
1.When the pay item "Traffic Control Management" is shown in the contract, the Contractor shall acco mplish the requirements in Section 419.02, Paragraph 1 and 2. This pay it em will only be utilized when directed by the Engineer.
2.When the pay item “Surveill ance of Temporary Traffic Control Devices” is shown in the contract, then the Contractor shall accomplish the requirements in Section 419.02, Para graph 1 and 3. This pay item will only be utilized when directed by the Engineer.
3.The Contractor shall be alert at all times to any and all deficiencies in the placement and maintenance of any traffic control devices and shall take immediate action to correct any deficiencies.
419.02 Construction Methods
1.Traffic Control Personnel a. The Traffic Control Manager shall be qualified by having attended and having satisfactorily passed the examination which accompanies the training course for Traffic Control Supervisor or Traffic Control Technician offered by the American Traffic Safety Services Association (ATSSA) or the Basic Traffi c Control or Advanced Traffic Control courses offered by Nebraska LTAP. The training shall have been completed no more than 4 years prior to working on the project. Other certifications may be accepted if approved by the Engineer. The Traffic Control Manager shall also possess a current valid Flagger Ce rtification Card. Documentation of the Traffic Control Manager's training or certifications shall be provided to the Engineer prior to the installation of any traffic control devices on the project.
b.The Assistant Traffic Cont rol Managers shall be qualified by certification according to the Department’s certificat ion program for Assistant Traffic Control Managers, the training shall have been completed no more than 2 years prior to working on the project. The Assistant Traffic Control Managers may be qualified by having attended and having satisfactorily passed the examination which accompanies the training course for Traffic Control Technician or Traffic Contro l Supervisor offered by ATSSA or the Basic Traffic Control or Advanced Traffic Control courses offered by Nebraska LTAP. The training shall have been completed no more than 4 years prior to working on the project. Do cumentation of the Assistant Traffic Control Manager's training or certificatio ns shall be provided to the Engineer. The Assistant Traffic Control Manager shall also possess a current valid Flagger Certification Card.
c.Department Ce rtification Program:
1.In order to be qualified according to the Department’s Certification Program, the prospective Assistant Traffic Control Manager must:
i.View the video “Traini ng and Certification of Assistant Traffic Control Managers.”
Source: Nebraska Standard Specifications for Highway Construction, 2017 Edition. Pages 261–275 of 1,048.