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The work covered by this section consists of furnishing and installing a high mount standard 75' or greater in height with a lowering device and portable drive unit.
(A) High Mount Standard:
The standard may be either a multisided or round tubular member. The Contractor shall furnish to the Engineer 8 copies of completely detailed drawings and 1 copy of the complete design computations for each height of standard for approval prior to fabrication. The drawings shall show all details relating to pole, access hole, base, anchorage, and lowering device. The drawings shall also show references to ASTM specifications or to other material specifications for each type of material used. All drawings shall be signed and dated by the manufacturer's authorized representative and they shall be clearly identified with a drawing number.
Full and complete information regarding location, type, size, and extent of all welds shall be clearly shown on the drawings. For groove welds, the particular detail and process to be employed in production of the work shall be indicated. For prequalified joints, use of the Bridge Welding Code letter classification designation of the joint (B-Lzb-S etc.) will satisfy this requirement.
The total weight in avoirdupois (pounds) and metric (kilograms) shall be noted on the drawings for each component and the total assembly.
The Contractor's attention is directed to the fact that it will take approximately 10 weeks to secure approval after submission of the complete drawings and computations.
The design of the support including base plate and anchorage shall conform to AASHTO "Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals" except the welding design and fabrication shall be in accordance with Article 107220 of the Standard Specifications. The support is to be designed for a wind velocity as required by AASHTO unless noted otherwise on the plans.
Fabrication of the support shall be in accordance with the details shown on the approved shop drawings and with the requirements of the specifications.
The support shall be fabricated of steel and shall be hot-dipped galvanized after fabrication has been completed.
The galvanizing shall conform to ASTM A153 for fasteners and to ASTM A123 for other structural steel.
All welding of steel components shall conform to the Standard Specifications with the following exception. Partial penetration longitudinal groove welds on shaft sections having a minimum throat of 60% of the thickness of material being joined will be acceptable provided the qualification requirements of the Bridge Welding Code are met. However, full penetration will be required on longitudinal groove welds within 6 inches of circumferential welds and in areas where a shaft section telescopes over another shaft section. No field welding of any part of the assembly will be permitted.
A handhole with hinged and lockable door shall allow easy access to all components in the base of the standard. Opening of the door shall not require the use of special tools or wrenches. The handhole shall be large enough for removal of the circuit breaker and the hoist gearbox and winch assembly (minimum 9" x 18"). The door hinge and lock mechanism shall be sturdy enough to prevent vandalism and shall not be subject to freeze-up or binding due to corrosion or too-tight fit. Locking shall be achieved with a conventional "pad-lock". Built in locks or latching mechanism for the door will not be acceptable.
(B) Lowering Device:
The Contractor shall furnish to the Engineer eight (8) copies of completely detailed drawings of the lowering device with manuals describing the assembly, erecting and operating procedures. This shall include precise instructions on stringing the cables and leveling the carrier ring.
Each high mount lighting standard shall have a device to lower the luminaires from the operating position at the top of the standard to a service position approximately 3' above the base of the standard. The device shall include a head-frame, carrier ring, and winch assembly. The lowering device shall be designed for the number of luminaires as shown on the plans, each weighing and each having a projected area as specified in the section titled "High Mount Luminaires".
The head frame shall be mounted on the standard with a slipfitter and set screws and shall have sheaves or rollers for the lifting and power cables. It shall also have sockets to automatically secure the carrier ring in the raised position and the entire assembly shall have a hood for protection from the weather. Latching and unlatching shall be attained by alternately raising and lowering the carrier ring.
Sheaves shall be non-corrosive materials with bronze bushings and stainless steel shafts. Suitable retainers shall be provided to assure that the cables stay in correct position.
The carrier ring shall have slipfitter tenons equally spaced for mounting the luminaires. It shall be automatically latched to the head frame when raised into position by suitable pins and sockets which will prevent the luminaires from swaying, turning, vibrating, or otherwise moving out of proper position. The carrier ring shall also have spring loaded roller arms to guide the ring during raising and lowering operations. The springs shall be stainless steel and the rollers shall be nylon. A weatherproof junction box shall be mounted on the ring for connection of individual luminaire circuits to the electrical power supply cable. The junction box shall include a flanged inlet for connection of the power supply cable. The inlet and cable connector shall be of the locking type and shall be weatherproof.
The winch assembly shall be a self-locking worm-gear type designed for operation with a portable power unit. The winch drum shall automatically reverse the lay of the hoist cable and not allow uneven build-up or tangling.
A terminator shall be provided for joining the hoist cable and 3 suspension or lifting cables. Means to compensate for variations in the lengths of the 3 lifting cables shall be provided. The hoist and lifting cables shall be stranded high strength stainless steel extra flexible aircraft type. The hoist and lifting cables shall meet structural requirements of Military Specification MILW83420D and the center strand shall not protrude more than .06 inch after the cable is cut.
The power supply cable shall be rated for suspension and shall have approved strain relief fittings at each end. At the base of the standard a locking type plug with waterproof cover shall be provided to connect to a short power supply cable stubbed from the circuit breaker panel.
(C) Portable Drive:
The portable drive unit shall be a heavy duty reversible electric motor with torque limiter type drive of adequate capacity complete with a grounding type cord, suitable couplings for attaching the unit to the winch assembly, and a sturdy storage container for the unit and accessories involved. One portable drive unit shall be provided for the completed project. The drive unit shall have a lever switch controller with clearly marked UP and DOWN positions. The controller shall be connected to the drive unit with a cord of sufficient length to let the operator stand a minimum of 15' from the base of the high mount during lowering or raising operations.
The portable drive unit shall be shop assembled and shall have all rough edges removed. The mounting or adjustment bolts shall allow hand tightening.
The complete unit shall be supplied in a durable metal storage case with all equipment and instructions for operation. The case shall be the approximate size as shown on the plans, it shall have a continuous hinge on the lid, and sturdy carrying handles on each end. A hasp with padlock shall be furnished as shown on the plans. The case shall be constructed of 16 gauge formed and welded steel with bracing to prevent warping. It shall be painted inside and outside with a durable quality paint. The storage case shall have an identification label as noted in the plans.
(D) Circuitry:
An enclosed circuit breaker shall be installed in the base of the high mount standard. This breaker shall be rated 480 VAC, 2 pole, 30 ampere unless noted otherwise on the plans.
The supply cord originating from the circuit breaker shall have a female twist lock connector for testing the luminaires at ground level, during lowering operation using the portable drive unit, and when in the raised position during normal night operation.
The junction box mounted on the lowering ring shall have a flanged inlet to accept the female twist lock connector from the supply cord. The plugs, flanged inlets, and connectors for the supply cable and drive unit shall allow grounding and shall be weatherproof.
The wiring for each high mount luminaire shall be installed separately from the luminaire to the junction box. Series or loop circuitry will not be allowed.
A transformer, branch circuit breaker, and receptacle shall be provided as a power source for the portable drive.
An equipment grounding conductor shall be provided in the supply cable. Wiring for each luminaire shall include an equipment grounding conductor.
(E) Operation:
The operation of the lowering device shall be demonstrated by the Contractor by raising and lowering the carrier ring with luminaires a minimum of five (5) times for each high mast. The raise and lower demonstration shall include latching and unlatching at the top and connection of test cables at the bottom. Twisting of the cables, failure of the carrier ring to latch or unlatch, unlevelness of the carrier, or hang-up of guide arms will be sufficient reason for the Engineer not to accept the lowering device.
Suitable blocking and slings shall be used to prevent warping of the high mount standard during storage and transportation. The Contractor shall assemble all parts and string all cables in strict accordance with the manufacturer's instructions.
The top of the standard shall not be out of plumb more than one half of one percent of its height.
Assembly instructions and any special tools, blocks, washers, etc. shall be included in the portable drive storage case.
All dirt, stains, marks, etc. shall be removed prior to erecting the high mast.
1401-4 MEASUREMENT AND PAYMENT.
The quantity of high mount standards with lowering devices to be paid for will be the actual number of standards which have been installed and accepted. High mount lighting standards with lowering device, measured as provided above, will be paid for at the contract unit price each for "__________ High Mount Standard" of the appropriate height.
Such price and payment will be full compensation for all work of furnishing and installing the standard, lowering device, winch, wiring, cables, brackets, and hardware.
The quantity of portable drive units with storage cases to be paid for will be the actual number of portable drive units which have been furnished and accepted. Portable drive units with storage case, measured as provided above, will be paid for at the contract unit price each for "Portable Drive Unit". Such price and payment will be full compensation for all work of furnishing the drive, transformer, power cord, storage case, and operating manuals.
Payment will be made under:
"__________ High Mount Standard" Each
Portable Drive Unit Each