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(1) Slotted bolt holes to take care of expansion shall be provided as called for on the plans.

(2) Anchor bolt holes may be up to 25 percent greater than the nominal bolt diameter with a maximum of 12-inch greater than the nominal bolt diameter.

(d) Contact with other materials.—Where aluminum alloys come in contact with other metals, the contacting surfaces shall be thoroughly coated with an aluminum-impregnated calking compound, or a synthetic rubber gasket may be placed between the two surfaces. Aluminum alloys shall not be placed in contact with copper, copper base alloys, lead, or nickel.

Where aluminum alloys come in contact with concrete or stone the contacting surfaces shall be thoroughly coated with an aluminum-impregnated calking compound. When bond between aluminum and concrete is desired, the aluminum shall be coated with zinc-chromate paint and allowed to dry before installation.

Where aluminum alloys come in contact with wood, the contacting surface of the wood shall be given three coats of paint as provided in the applicable provisions of subsection 611.24 and the contacting aluminum surface shall be coated with an approved aluminum calking compound.

612.14 Timber Railing. Erection of timber railing shall be in conformity with the requirements of section 613.

612.15 Painting. All steel railing, except beam type railing, shall be cleaned and given one primer coat and two field coats of paint in conformity with the requirements of subsections 611.22 through 611.24. Beam type railing shall be painted in conformity with the requirements of section 606. If galvanizing is shown on the plans in lieu of painting; the requirements of AASHO M111(ASTM A123) or ASTM A525 shall apply. Timber shall be painted with three coats of white lead paint in conformity with the requirements of subsection 611.24.

Method of Measurement

612.16 The quantity to be paid for under this item will be the number of near feet of bridge railing of the several types, complete in place and accepted, measured along the line and grade of the railing from end to end of end posts. It will include all work constructed above the top of the curb and all fastenings and anchors required to attach the railing to the structure. It will include that portion of reinforcement steel for railing which extends into the curb. Lump sum measurement, if called for in the bid schedule, will be in accordance with subsection 109.01.

Basis of Payment

612.17 When the bid schedule contains an estimated quantity for any of the pay items below, the quantity, determined as provided above, will be paid for at the contract price per pay unit or lump sum respectively, for each of the particular pay items listed below that is shown in the bid schedule, which price and payment will be full compensation for the work prescribed in this section. When the plans or special provisions provide for the construction of bridge railing for which the bid schedule contains no estimated quantity or lump sum under any one of the pay items below, such railing will be considered as an integral portion of the structure to which it is attached and will be paid for as provided under the applicable section covering the bridge construction. Payment will be made under: Pay item

Pay unit 612(1) Concrete bridge railing

Linear foot. 612 (2) Steel bridge railing

Linear foot. 612 (3) Aluminum alloy bridge railing Linear foot. 612 (4) Timber bridge railing

Linear foot. 612 (5) Bridge railing

Lump sum. When more than one design of railing is specified for any one pay item, letter suffixes will be included as part of the item numbers and dimensions or other means of identification inserted in parentheses immediately after the pay item names.

Section 613.-TIMBER STRUCTURES

Description 613.01 This work shall consist of timber structures and the timber portions of composite structures, constructed in reasonably close conformity with the lines, grades, dimensions and designs shown on the plans or ordered in writing by the Engineer.

It will include the furnishing, preparing, erecting, and painting of strucural timber of the stress values, sizes, and dimensions specified, treated or untreated as called for in the bid schedule. Also included will be any required yard lumber of the sizes and grades specified and all hardware, as shown on the plans or ordered by the Engineer.

Materials

613.02 Materials shall meet the requirements of the following subsections: Structural timber and lumber

716.01 Hardware

716.02 Paint

708.02 Treated timber

716.03 Structural Shapes, Rods, and Plates. All structural shapes, rods, and plates shall be of structural steel or wrought iron, as specified or indicated on the plans, meeting the requirements prescribed in section 611. All eyebars and castings shall conform to the requirements therefor prescribed in section 611. No welds will be permitted in truss rods, or in main members of trusses or girders.

Construction Requirements 613.03 Workmanship. None but experienced bridge carpenters shall be employed and all framing shall be true and exact. Unless otherwise specified, nails and spikes shall be driven with just sufficient force to set the heads flush with the surface of the wood. Deep hammer marks in wood surfaces will be considered evidence of poor workmanship and sufficient cause for removal of the workman responsible for them. The workmanship on all metal parts shall conform to the requirements specified for those materials.

613.04 Storage of Materials. All lumber and timber on the site of the work shall be stacked to prevent warping. Untreated material shall be open-stacked at least 12 inches above the ground surface and so piled as to shed water. When required by the Engineer, it shall be protected from the weather by suitable covering. Creosoted timber shall be close-stacked and, when required by the Engineer, the stacks shall be covered with a 2-inch layer of earth. The ground underneath and in the vicinity of all stacks shall be cleared of weeds and rubbish.

613.05 Treated Timber. Treated timbers shall be framed before treatment and shall be handled carefully without dropping, breaking of outer fibers, or bruising or penetrating the surface with tools. Cant dogs, hooks, or pike poles shall not be used. In coastal waters, cutting and boring below highwater mark shall be avoided. All cuts in creosote treated piles, timber, and lumber, and all abrasions, after having be carefully trimmed, shall be coated with two applications of a mixture of 60 percent creosote oil and 40 percent roofing pitch or shall be brush-coated with at least three applications of hot creosote oil and covered with

hot roofing pitch. All cuts and abrasions in timber or lumber, that have been treated with an oil-borne or water-borne preservative, shall be given three brush-coats with the same type of preservative used in the original treatment. This requirement may be waived if the timber and lumber are to be painted.

Before driving bolts, all holes bored after treatment shall be impregnated with hot creosote oil by means of an approved bolt-hole treater. Any unfilled holes, after being treated with creosote oil, shall be plugged with creosoted plugs.

613.06 Untreated Timber. In structures of untreated timber, the surfaces named below shall be coated thoroughly with two coats of hot cresote oil before the timbers are assembled: ends, tops, and all contact surfaces of posts, sills, caps, floor beams, and stringers, all ends, joints, and contact surfaces of bracing and truss members. All surfaces of timber bumpers, the back faces of bulkheads, and of all other timber which is to be in contact with earth shall be similarly treated.

613.07 Holes for Bolts, Dowels, Rods, and Lag Screws. Holes for round driftbolts and dowels shall be bored with a bit one-sixteenth inch smaller in diameter than that of the bolt or dowel to be used. The diameters of holes for square driftbolts or dowels shall be equal to one side of the bolt or dowel. Holes for machine bolts shall be bored with a bit of the same diameter as that of the bolt. Holes for lag screws shall be bored with a bit not larger than the body of the screw

the base of the thread. 613.08 Bolts and Washers. Washers of the size and type specified shall be used in contact with all bolt heads or nuts that would otherwise be in contact with wood. Cast-iron washers shall have a thickness equal to the diameter of the bolt, and the diameter of the washer shall be four times its thickness. For malleable or plate washers the diameter or side dimensions of the square shall be equal to four times the diameter of the bolt, and the thickness shall be equal to onehalf the diameter of the bolt. Cast-iron washers shall be used when the timber is in contact with the earth. All nuts shall be checked or burred effectively with a pointed tool after being finally tightened, to prevent turning.

613.09 Countersinking. Countersinking shall be done wherever smooth faces are required. Recesses formed for countersinking, except in railings, shall be painted with hot creosote oil and, after bolts or screws are in place, shall be filled with hot pitch.

613.10 Framing. Subject to the requirements of subsection 613.05 for treated timber, all lumber and timber shall be accurately cut and framed to a close fit so that the joints will have even bearing over the entire contact surfaces without shimming.

Slabbing or trimming of treated piles for fitting sway or sash braces will not be permitted. The spaces intervening between the braces and the smaller piles shall be filled with treated blocks so that the bracing is securely fastened to the piles.

613.11 Framing Bents. Mud blocks shall be firmly and evenly bedded to solid bearing and tamped in place.

Concrete pedestals for the support of framed bents shall be finished carefully so that sills or posts will bear evenly upon them. Dowels for anchoring sills and posts shall be set when the concrete is cast and shall project at least 6 inches above the tops of the pedestals.

Sills shall have true and even bearing on mud blocks, piles, or pedestals. They shall be driftbolted with bolts extending into the mud blocks or piles at least 6 inches. When possible, all earth shall be removed from contact with sills so that there will be a free circulation of air around the sills.

613.12 Caps for All Bents. Timber caps shall be placed to obtain even and uniform bearing over the tops of the supporting posts or piles and with their ends in alinement. All caps shall be secured by driftbolts, set approximately at the center and extending at least 9 inches into the posts or piles.

613.13 Bracing. The ends of bracing shall be bolted through the pile, post, cap, or still. Bracing at intermediate intersections with posts or piles shall be bolted, or spiked with wire or boat spikes, as indicated on the plans. In all cases spikes shall be used in addition to bolts.

613.14 Stringers. Stringers shall be sized at bearings and shall be placed in position so that knots near edges will be in the top portions of the stringers.

Outside stringers may have butt joints with the ends cut on a taper, but interior stringers shall be lapped to take bearing over the full width of the floor beam or cap at each end. The lapped ends of untreated stringers shall be separated at least 12 inch for the circulation of air and shall be securely fastened by drift-bolting where specified. When stringers are two panels in length the joints shall be staggered.

Cross-bridging between stringers shall be neatly and accurately framed and securely toe-nailed with at least two nails in each end. All cross-bridging members shall have full bearing at each end against the sides of stringers. Unless otherwise specified in the contract, cross-bridging shall be placed at the center of each span.

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