(1) PROPOSALS AND GENERAL REQUIREMENTS

101. The General Specifications for Steel Railway Bridges of the American Railway Engineering Association, 1920, with additions and revisions, shall apply to movable bridges except as provided otherwise herein.

Responsibility.

102. Unless otherwise provided, the fabricating contractor shall be responsible for the complete installation of the superstructure and the operation of the moving span as far as pertains to the materials, workmanship, and erection, and the designing of parts and details which are not covered by the proposal plans. The Contractor shall furnish and erect the structure ready for the application of power for its operation and to receive trains.

Time of Opening.

103. The normal time for opening the bridge after the ends are released shall be as specified on the proposal drawings for both the main and the auxiliary powers.

Machinery Drawings.

104. Unless otherwise provided, the Contractor shall furnish an outline drawing of the machinery on which are shown the forces acting on the gear teeth, the twisting moment and the bending moment on shafts, and other information necessary for computing the strength of the machinery parts. The Contractor shall make an assembly drawing and detail drawings of the machinery. These drawings shall be so complete that the machinery parts may be duplicated without reference to patterns, other drawings, or individual shop practice.

Torque Curves.

105. The Contractor shall show by curves the torque to be exerted at the motor pinion as follows:

(a) Torque curves for acceleration and for retardation.

(b) A torque curve for the frictional resistance. The torque for starting friction shall not be combined with the torque for acceleration.

(c) A torque curve for any unbalanced condition of the structure. (d) A torque curve for the wind loads.

(e) A torque curve showing the greatest resultant combination of resistances acting at one time. The torque curves of the motors under various operating conditions shall be superimposed on this curve.

Weight and Center of Gravity.

106. The Contractor shall determine the weight and (where necessary) the location of the center of gravity of the moving span, including

Proposals and General Requirements.

parts attached thereto; also of the counterweights, including their frame work. These determinations shall be based on weights carefully computed from shop plans. The computations, accompanied by weight bills, shall be submitted to the Company in form for verification.

Houses.

107. The Contractor shall furnish and build the machinery house. The house for the operator and the signal devices shall be built by the Contractor or the Company as may be stipulated.

Signals and Interlocking.

108. The Company will furnish and install the railway signal system, including the master lever and the devices necessary for interlocking the signal system with the moving span. The Contractor shall furnish and install the devices necessary for interlocking the parts of the bridge machinery with each other and for connection to the master lever. The operating machinery and the electrical parts shall be so designed that the signal system may readily be installed and attached.

Warning Lights.

109. The Contractor shall furnish and install (including wiring) on the moving span and piers, navigation lights and other signals required by the United States Government or other authorities, and shall provide suitable means of access to such lights.

Wrenches.

110. Two sets of wrenches to fit heads and nuts of bolts for the machinery shall be furnished by the Contractor.

Defects.

111. If any defects due to faulty workmanship or erection, or defective material, or design for which the Contractor is responsible, are found within one year after the final test and acceptance, the Contractor shall remedy such defects at his own cost. If necessary, the Company may remedy such defects at the expense of the Contractor.

Classification of Parts.

112. The parts of the bridge shall be classified as follows, and unless otherwise stipulated, paid for as indicated:

(a) Structural steel, by the pound.

(b) Machinery, by the pound.

(c) Engines, boilers and tanks, a lump sum.

(d) Electrical equipment, a lump sum.

(e) Wire ropes and wire rope attachments, by the pound.

(f) Houses for machinery and for operators, a lump sum.

(g) Sheaves for counterweights, by the pound.

(h) Metal in counterweights, by the pound.

(i)

Concrete, by the cubic yard.

(j) Timber deck and track, by the linear foot of track.

(k) Timber walks, by the thousand feet, board measure. Nominal

dimensions of timbers to govern.

(1) Balancing chains, by the pound.

Proposals and General Requirements.

Parts not classified under headings (b) to (1) inclusive, shall be classified under (a), structural steel.

Payment by the pound shall be based on scale weights of the finished material.

113. Parts included in the different classes shall be:

(a) STRUCTURAL STEEL: In addition to the moving span, any parts of rolled or cast steel which can be fabricated by the common shop methods of punching, reaming, drilling, boring, shearing, planing, bending, etc., usual for stationary structures.

Rim girders in swing bridges, segmental girders in rolling bascule bridges and the girders on which they roll, parts supporting the machinery, counterweight frames, counterweight trusses, operating struts, towers, steel framing and plates in houses for machinery and operators, hand rails, stairways, ladders, and specially fabricated track rails, shall be classified as structural steel.

(b) MACHINERY: Winding drums, tread plates, pedestals, wedge bases, center pivot stands, pistons and their cylinders, eccentrics, pivots, trunnions and their cast supports, shafts, spools, gears, racks, bearings, couplings, clutches, brakes (unless part of the motors), discs, cast sheaves and wheels, rollers, cast roller treads and guides, worm gearing, valves, pins about whose axes the connecting members rotate, screws, wedges, toggles, bridge locks, rail locks, indicators, whistles, cranks, axles, hooks, wrenches, turned bolts attaching machinery parts, and similar parts which require machine shop work and which are not included in any other class. Machinery parts attached to structural parts shall be weighed sepa

rately.

(c) ENGINES, BOILERS AND TANKS: Internal combustion engines, steam engines, pumps, compressors, anchor bolts, steam boilers and stacks, air compressor tanks and other tanks, with their fittings and piping.

(d) ELECTRICAL EQUIPMENT: The switchboard with its attachments and electrical parts beyond (whether on or off the moving span), such as motors, controllers, solenoids, conductors, conduits and their fittings, lamps, blow-outs, cut-offs, circuit breakers, contactors, switches, trolley poles, trolley wheels and contact shoes.

Electrical equipment carrying the current to the switchboard from the source of power will be covered by a separate contract.

(e) HOUSES FOR MACHINERY AND OPERATORS: All parts of such houses except steel framing and plates.

(f) WIRE ROPES AND WIRE ROPE ATTACHMENTS: Ropes with their attached sockets, and fastenings of the ropes to the trusses and counterweights, including pins and equalizing devices.

(g) COUNTERWEIGHT SHEAVES: Cast or built sheaves, together with their axles and bearings.

(h) METAL IN COUNTERWEIGHTS: Only cast iron and scrap metal used in counterweights.

(i) CONCRETE: Concrete and reinforcing bars used in counterweights, and concrete in pockets of column bases and similar places. No deductions shall be made for enclosed metal.

Proposals and General Requirements-Design.

(j) TIMBER DECK AND TRACK: Placing and permanently fastening the timber deck and track. Unless otherwise specified the Company will furnish the deck and track material and fastenings, except rail-locks, specially fabricated rails, and special devices to hold the deck in place.

(k) TIMBER WALKS: Furnishing and placing lumber in walks, platforms, etc., together with nails, bolts, and other fastenings.

(1) BALANCING CHAINS: Chains and their fastenings used for balancing the counterweight ropes.

Types.

201.

(2) GENERAL FEATURES OF DESIGN.

Movable bridges preferably shall be of the following types:

The type to be used will be determined by the Engineer. Pin connected trusses shall not be used.

Counterweight.

202. The counterweight shall be sufficient to balance the moving span and its attachments in any position. In vertical lift bridges, the counterweight ropes shall be balanced by chains unless otherwise specified. Aligning and Locking.

203. Movable bridges shall be equipped with suitable mechanism to align them accurately and to lock them securely in position so that they cannot be displaced either horizontally or vertically under the action of traffic. The operating mechanisms of end lifts and rail locks shall be independent.

Auxiliary Power.

204. Bridges operated by mechanical power shall be equipped with auxiliary power. The auxiliary power shall be hand or mechanical, as determined by the Engineer.

Interlocking.

205. The bridge operating devices shall permit interlocking with the signal system. They shall be so interlocked with each other that the operations, both for opening and closing the bridge, must be performed in a predetermined order.

Insulation of Track.

206. The connections of parts in contact with the track shall be such as to prevent all possibility of short circuiting of track signals. Houses for Machinery and Operators.

207. If mechanical power is to be used for operating the bridge, a suitable house shall be provided for the machinery and the operator. The house shall be large enough for easy access to all machinery. The

General Features of Design.

house shall be fireproof and weatherproof. There shall be at least one window in each side of the house.

The floor shall be built of concrete. It shall be smoke tight and have a non-slip surface.

If the operator is not located in the machinery house, or if the bridge is hand operated, a house shall be provided for him. The type of construction shall be the same as that specified for the machinery house, except that for hand-operated bridges with the house located off the bridge structure, fully fireproof construction will not be required.

Provision shall be made for the heating apparatus to be installed by the Company in the operator's house.

If stipulated, a 5-ton capacity hand operated overhead traveling crane shall be installed in the machinery house.

Stairways and Walks.

208. Metal stairways, platforms, and walks with railings shall be provided, for access to the operator's house, machinery, trunnions, counterweights, lights, bridge seats, and similar parts. Ladders may be installed only where stairways are not feasible. In vertical lift bridges, ladders and walks shall be installed to give access to the moving span in any position from either tower. Hand railings shall be made of gas pipe not less than 11⁄2-inch size. Stairways and ladders shall be of metal. The treads may be channels filled with concrete.

Materials Used.

209. Materials in machinery and similar parts shall be as follows: ROLLED STEEL OR FORGED STEEL: For trunnions, shafts, axles, bolts, nuts, keys, cotters, pins, screws, worms, piston rods, and crane hooks.

Shafts up to 6 inches in diameter may be either rolled or forged; shafts larger than this shall be forged. Shafts larger than 31⁄2 inches in diameter shall not be cold rolled.

FORGED STEEL OR CAST STEEL: For rim girder tread plates, levers, cranks, connecting rods, and rollers.

FORGED STEEL: For pinions and equalizing levers.

CAST STEEL: For pivot stands, couplings, wedges, wedge bearings, trailing wheels, end shoes, racks, tracks, winding drums, gears, brake wheels, sheaves on lift bridges, trunnion bearings and shaft bearings and hangers. Large sheaves may be built of structural steel and cast steel.

TOOL STEEL: For parts which require hardening or oil tempering, such as pivots, friction rollers, ball bearings and springs.

PHOSPHOR-BRONZE: For pivot discs, worm wheels, linings of the trunnion bearings of bascule and lift bridges, linings of other large bearings carrying heavy loads, and such gears and nuts as are required to be of bronze.

PHOSPHOR-BRONZE, BRONZE, OR BABBITT METAL: For the linings of journal bearings and of other rotating or sliding parts.