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The work covered by this section consists of the design, fabrication, furnishing and erection of various types of overhead sign structures with maintenance walkways, and the attachment of Type A and Type B signs to the structure in accordance with the requirements of the plans and the provisions of these specifications.
The supporting structures shall be fabricated from tubular members of either aluminum or steel, but only one type of material may be used throughout the project.
Among the types of overhead sign assemblies included in this specification are: span structures, cantilever structures, and sign structures attached to bridges.
The Contractor shall design the overhead sign assemblies, including footings, and submit shop drawings for approval.
The provisions of Section 900 will be applicable to all work covered by this section.
All materials shall meet the requirements of Division 10 shown below:
Structural steel Section 1072 and 1096
Structural aluminum Section 1096
Class A concrete Section 1000
Steel bar reinforcement Section 1070
Anchor bolts Article 1072-6
Joint sealer Article 1028-2
Zinc-rich paint Article 1080-9
High strength bolts, nuts, and washers Subarticle 1094-1(A)
(A) General:
All overhead sign assemblies shall be fabricated in accordance with the details shown in the approved shop drawings and the requirements of these specifications.
Sign panels for overhead sign assemblies shall be fabricated in accordance with the requirements for Type A or Type B signs, as indicated in the plans, unless otherwise approved by the Engineer.
No welding, cutting, or drilling in any manner will be permitted in the field, unless approved by the Engineer.
Bolt holes and slots shall be drilled to finished size or they may be punched to finished size, provided the diameter of the punched holes is at least twice the thickness of the metal being punched. Flame cutting of bolt holes and slots will not be permitted.
Two coats of a zinc-rich paint shall be used in touching up minor scars on all galvanized materials.
(B) Shop Drawing:
The Contractor shall submit to the Engineer for approval a complete design for each overhead sign assembly, including footings and brackets for supporting the signs, maintenance walkways, and lighting luminaires. Such design shall be based upon the line drawings and wind speed shown in the plans, and shall be in accordance with the "Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals".
Thirteen copies of completely detailed shop drawings and one copy of the design computations for each overhead sign assembly shall be submitted to the Engineer for approval prior to fabrication. Shop drawings shall show complete design and fabrication details, including foundations, provisions for attaching signs, maintenance walkways, and lighting luminaires to supporting structures, applicable material specifications, and any other information necessary for procuring and replacing any part of the complete overhead sign assembly.
The Contractor shall allow at least 50 days for shop drawing approval after they are received by the Engineer. If revised drawings are required, appropriate additional time will be required for review and approval of final shop drawings.
Approval of shop drawings by the Engineer shall not relieve the Contractor of his responsibility for the correctness of his drawings, or for the fit of all shop and field connections and anchors.
(C) Design and Fabrication:
(1) Overhead Sign Assemblies:
Fabrication of all overhead sign assemblies shall be in accordance with the details shown in the approved shop drawings and with the requirements of these specifications.
Overhead sign assembly dimensions shown in the plans were estimated from available project data for bid purposes. The Engineer will determine the actual dimensions from field measurements and will furnish revised plans to the Contractor.
Horizontal components of the supporting structures for overhead signs may be of a truss design or a design using singular horizontal members to support the sign panels. Permanent camber in addition to dead load camber shall be provided in accordance with the "Standard Specifications for Structural Supports for Highway Signs, Luminaires, and Traffic Signals". The shop drawings shall indicate the amount of camber provided and the method employed in the fabrication of the assembly to obtain the camber.
Cantilever sign assemblies shall also meet the following design criteria:
1. Vertical dead load deflection at the end of the arm shall not exceed L/150 due to distortions in the arm and vertical support, where L is the length of the arm from the center of the vertical support to the outer edge of the sign.
2. The horizontal deflection at the end of the arm shall not exceed L/40 due to distortions in the arm and vertical support, as a result of design wind load.
The overhead sign assemblies shall be attached to concrete foundations by the use of galvanized anchor bolts. Anchor bolts shall be furnished with galvanized nuts, flat washers, and lock washers. The anchor bolts shall have a right angle bend or anchor plate with nut at the end to be embedded in concrete.
Attachment assemblies for mounting signs shall be fabricated in a manner which will insure easy removal of the sign panels for repairs.
All overhead sign assemblies which are to be illuminated shall be provided with adequate supporting frames for mounting the lighting luminaires in the positions shown in the plans or approved shop drawings.
(2) Maintenance Walkways:
Maintenance walkways with an open, skid-resistant surface and safety railings shall be provided on all overhead structures unless specifically stated otherwise in the plans. Requirements for design and fabrication of the walkways are shown in the plans. The walkway shall be continuous and shall extend from 3 feet outside the edge of pavement over the shoulder to the farthest edge of any sign on the structure. If a sign is to be located such that it extends more than 3 feet outside the edge of pavement, the walkway shall also extend for the full length of that sign. These walkways shall have a safety railing along the front side which can be folded, when not in use, to a horizontal position which will not obscure the signs. To accommodate lighting luminaires, supports for the walkways shall extend in front of the walkway and railing. If external ballasts are required, provisions shall be made adjacent to the walkway and between the walkway and sign to accommodate ballast boxes for lighting circuits in a manner readily accessible from the walkway. The ballast box, brackets, and fastening devices shall withstand the loading requirements for the walkway, and shall be so mounted that the top of the box will be flush with the top of the walkway.
The walkway sections are to be connected rigidly where sections join to avoid an uneven walking surface. The walkway shall be attached directly to the walkway brackets.
A 4 inch x 4 inch safety angle shall be installed in back of and parallel to the walkway and shall extend the entire length of the walkway, except in the area occupied by ballast boxes. The safety angle shall be designed to withstand a loading in keeping with the walkway.
Folding safety railing shall be fabricated in lengths not exceeding 10 feet and shall be installed for the full length of the walkway. Each folding safety railing post shall be joined to walkway supports through a hinge assembly of appropriate design which will rotate freely. The hinge assembly shall have a locking or latching device and shall hold the railing in a steady manner, free of movement while in the raised position. Maximum allowable displacement from vertical at the top of the railing shall be 1 inch.
Fixed safety railing shall be installed along the sign side of the walkway from the beginning of the walkway to the edge of the first sign. Fixed safety rails shall be provided between signs when they are greater than 12 inches apart. One fixed safety rail shall be provided below any sign having a clearance between the bottom of the sign and the walkway grating of greater than 24 inches and less than 42 inches. Two fixed rails shall be provided when the clearance between the bottom of a sign and the walkway exceeds 42 inches.
The open ends of the walkway shall have a galvanized steel coil safety chain attached on one end near the top of the safety railing, and on the other end to the walkway hanger, or other fixed member of the structure. When the railing is folded, the chain shall not hang below the walkway bracket.
Where offsets in the walkway and safety railing are necessitated by variable luminaire offsets, safety chains shall be provided between the offset handrail sections.
(3) Footings:
Footings shall be designed for the combined effects of dead and wind loads and may be either spread type or pole type. Spread footings shall be designed for a maximum soil bearing of 3 ksf, unless otherwise allowed by the "Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals". If, in the judgement of the Engineer, the soil in a given footing excavation is not adequate for 3 ksf bearing pressure, or any other bearing pressure noted on approved footing drawings, the Contractor may be required to change his footing design to meet actual soil conditions at no cost to the Department.
(D) Location:
The Engineer will establish the location of each overhead sign assembly longitudinally. The Contractor will be responsible for the proper elevation, offset, level, and orientation of all sign assemblies.
(E) Footings for Overhead Sign Assemblies:
The Contractor shall perform all excavation and backfill necessary for footing construction to the elevations and dimensions shown in the plans or as directed by the Engineer.
All backfill shall be thoroughly compacted in 6 inch layers. The Contractor shall remove all excavated material that is not needed from the site.
Footing excavation for overhead sign assemblies shall conform to the applicable provisions of Section 410. The sides of the excavation for pole-type footings shall conform as nearly as practicable to the required dimensions. Concrete for pole-type footings shall be placed against undisturbed soil, unless otherwise permitted by the Engineer. If, in the judgement of the Engineer, significant discontinuities in the required configuration of the excavation for pole-type footings are created by the removal of boulders, or as a result of other causes, the excavation shall be backfilled and compacted as provided for in Section 410. The footings shall then be re-excavated to the proper dimensions. Shoring, if used to stabilize the sides of excavation for pole-type foundations, shall have been approved by the Engineer prior to its use.
Footings for overhead sign assemblies shall be constructed in accordance with Section 825. All footings shall be constructed of Class A concrete. Where rectangular forms are used, the forms shall have a chamfer strip at all corners for at least that distance protruding above ground level. The chamfer shall measure one inch along the diagonal face. Anchor bolts positioned in the form shall be securely braced, and held in proper position and alignment. Concrete surfaces to be exposed above finished ground shall have a rubbed finish in accordance with Subarticle 8256(D). Overhead sign assemblies shall not be erected on footings until the concrete has reached a minimum compressive strength of 3,000 psi. Concrete compressive strength shall have been evidenced by nondestructive test methods, or by compressive strength tests made in accordance with AASHTO T22 and T23. Equipment used for nondestructive tests shall be furnished by the Contractor, and shall have been approved by the Engineer.
The space between the top of the footing and the bottom of the base plate shall be filled and neatly finished with a non-shrinking grout approved by the Engineer.
The work covered by this section will be paid for at the contract lump sum price for "Overhead Sign Assembly ______". Such price and payment will be full compensation for all work covered by this section including but not limited to all design, fabrication, construction, transportation, and erection of the complete overhead sign assembly, supporting structure, hardware, lighting support brackets, maintenance walkways, and footings;preparing and furnishing shop drawings; and attaching the signs to the overhead sign assembly.
Payment will be made under:
Overhead Sign Assembly _____ Lump Sum