5-332 SECTIO N 544 – PREFABRICATE D BRIDG E UNIT SUPERSTRUCTURE 544.0 1 DESCRIPTION . This work shall consist of manufacturing, transporting, and erecting concrete and steel composite Prefabricated Bridge Units (PBUs) as shown on the Plan s. The work under this section shall be performed in accordance with these provisions, the Plan s, and Section 501, Section 506 , Section 507 , and Section 508 . 544.0 2 MATERIALS . Materials shall meet the material requirements specified in Subsection 501.02 , Subsection 506.02 , Subsection 507.02 , and Subsection 508.02 . 544.0 3 GENERA L FABRICATIO N REQUIREMENTS . The structural steel furnished under this section shall be fabricated in a p lant meeting the requirements of Subsection 506.03 . After fabrication, the structural steel shall be transported to a location approved by the Agency where the steel will be shop galvanized , metallized , or painted, or where the remainder of the composite superstructure unit will be fabricated. The fabricator or Contractor constructing the reinforced concrete portion of the PBUs shall have demonstrated experience in forming, casting, curing, and finishing performance -based concrete superstructure decks in accordance with Section 501 . 544.0 4 SUBMITTALS . As soon as practical after award of the Contract, all required information shall be prepared and submitted. Fabrication drawings and erection plans shall be su bmitted as separate submittals. Fabrication drawings for the PBUs shall be submitted in accordance with Subsection 105.06 . In addition to the requirements for fabrication draw ings in Subsection 105.06 , the following shall be included:
a.Structural steel information i n accordance with Subsection 506.04 .
b.Dimensions and tolerances of the sections to be fabricated .
c.The location of reinforcing steel, splices, welded wire fabric, mechanical bar connectors, and inserts . Reinforcing steel material lists, material designations, and bending details shall also be included.
d.The type of concrete surface finish and how the finish will be obtained .
e.The concrete curing method, detailing sequence , and duration in accordance with the requirements of Subsection 501.1 5. 5-333 (f) Temporary assembly plan and procedure .
g.Temporary support elevations .
h.Method of supporting the screed .
i.The design of the lifting attachments. A professional engineer shall stamp all calculations. Lifting attachments are not required to be permanently installed in the work and may be removed or left in place at the Contractor’s convenience, provided that the minimum clear cover is met.
j.Transportation, handling, a nd storage details along with calculations to substantiate that the PBUs will not be cracked or damaged by handling or transport. A professional engineer shall stamp all calculations. 544.0 5 INSPECTION . Structural steel shall be inspected by the Agency in accordance with Subsection
106.04 and Section 506 .
Concrete elements furnished and the work performed herein shall be inspected by the Agency. The inspector shall have the authority to reject any material or work that does not meet the requirements of these specifications. Advance notification of at least 14 calendar days shall be provided by the Contractor to the Engineer and the Structural Concrete Engineer concerning the proposed intention to commence work. A minimum notification of 5 working day s shall be provided by the Contractor to the Engineer and the Structural Concrete Engineer to confirm the fabrication start date. 544.0 6 FABRICATION .
a.Forming Members . Forms and formwork shall meet the requirements of Subsection 501.0 8. Relative bearing elevations shall be within ± 0.01 feet of that shown on the Plan s.
b.Structural Steel . Structural steel shall be fabricated in conformance with Section 506. All diaphragms shown on the Plan s shall be installed prior to placing any concrete formwork.
c.Welding . All welding shall conform to the requirements of Subsection 506.10 .
d.Reinforcing Steel . Bar reinforcement shall be furnished and installed in conformance with Section 507.
e.Concrete . Concrete mix and proportioning shall meet the requirements of Subsection 501.03 for Performance -Based Concrete, Class PCD. Concrete shall be produced and te sted in accordance with Subsection 501.04 through Subsection 501.07 . 5-334 (f) Pre-Production Meeting . Unless the Engineer deems, in writing, that a pre -production meeting is unnecessary, then a pre -production meeting shall be held a minimum of 7 calendar day s prior to beginning concrete placement. The pre -production meeting shall be attended by, but not be limited to, the crew supervisor, Contractor project manager, concrete producer, Engineer , Construction Structures Engineer, and Project Manager .
g.Placing Concrete . Concrete placement shall conform to the requirements of Subsection 501. 09. Concrete shall not be deposited in the forms until the Agency representative has approved placement o f the reinforcement and inserts. The concrete shall be vibrated internally, externally, or a combination thereof to the required consolidation. The vibrating shall be done with care and in such a manner that:
1.Concrete is uniformly consolidated
2.Displacement of reinforcement and inserts is avoided
3.Acceptable finish surfaces are produced
h.Curing . Curing shall meet the requirements of Subsection 501.1 5.
i.Removal of Forms . Forms shall not be removed until the curing period has ended.
j.Concrete Finishing . Finishing shall conform to the requirements of Subsection 501.1 4.
k.Dimensional Tolerances .
1.Geometry of PBU s.
a.The l ength of each unit shall be within a tolerance of ± 3/4 inch (i.e. a djacent unit lengths shall not vary by more than 3/4 inch ).
b.The width shall be within a tolerance of ± 3/8 inch.
c.The d eck thickness shall have a tolerance of + 3/8 inch, - 1/4 inch .
d.The allowable d eviation from diagonals shall be ± 3/4 inch (horizontal) .
e.The allowable d eviation from end squareness or skew shall be ± 3/4 inch (horizontal) . 5-335 f. The tolerance for g irder spacing within a unit shall be ± 1/2 inch .
g.The tolerance for h orizontal alignment , measured as the deviation from a straight line parallel to the centerline of the unit, shall be ± 3/8 inch .
h.The tolerance for i nsert location s shall be ± 3/8 inch .
2.Reinforcing .
a.The tolerance for reinforcing s pacing shall be ± 1 inch (non -cumulative) .
b.The tolerance for reinforcing clear c over on the top and bottom mat shall be ± 1/4 inch.
3.Field Installation .
a.The v ertical deviation between units prior to closure pour concrete placement shall not exceed 1/4 inch.
b.The allowable d eviation in joint width between units shall be ± 1/2 inch.
l.Acceptance of Units . Individual precast units will not be accepted for any of the following reasons:
1.Fractures or cracks passing through the deck
2.Camber that does not meet the requirements in the approved fabrication draw ings
3.Honeycombed open texture
4.Dimensions not within the allowable tolerances as specified
5.Separation of the concrete deck from the steel girders
6.Defects that indicate proportioning, mixing, and molding not in compliance with the specifications
7.Damaged ends wher e such damage would prevent making a satisfactory joint
8.Units with cracks within any part of the concrete that are greater than 0.03 inches in width
9.Significant damage to the units during transportation, erection, or construction as determined by t he Engineer
10.Units not fabricated in accordance with the Contract 5-336 (m) Repairing and Patching . Units that contain minor defects caused by manufacture or handling may be repaired at the manufacturing site. Minor defects are defined as holes, honeycombi ng, or spalls which are 6 inches or less in diameter and do not penetrate deeper than 1 inch into the concrete. Surface voids or bug holes that are less than 5/8 inch in diameter and less than 1/4 inch deep need not be repaired. Repairs shall be made using an overhead and vertical concrete repair material satisfactory to the Engineer. The repair material shall be cured as specified by the manufacturer. Repairs shall be approved by the Engineer.
n.Crack s. Crack widths less than 0.01 inch in width shall be sealed with a penetrating sealer using Agency approved materials and procedures. Crack widths measuring 0.01 inch to 0.03 inch in width shall be epoxy injected using Agency approved materials and procedures. At the Engineer’s discretion, cracked members sh all be repaired or replaced at the Contractor’s expense.
o.Labeling . Each unit shall be clearly and permanently labeled on the underside of the deck (in the vicinity of the upstation end diaphragm) with the following information:
1.Manufacturer
2.Date of manufacture
3.Mark number
p.Production Site Handling . Units shall not be lifted, moved, or otherwise disturbed until the curing period is complete and the concrete has reached full design strength.
q.Pre-Assembly . The units shall be pre -assembled at the fabrication location to ensure proper match between adjacent units before shipping to the project site, to the satisfaction of the Agency.
r.Shipping . Units shall not be shipped until the minimum 28 -day strength is attained and they have been stamped by the Agency. The Contractor shall give the Engineer 48-hours’ advance d notice of the loading and shipping schedule. The units shall be secured on the vehicle in order that no fatigue cracking will occur during tran sport. The Contractor shall secure the necessary hauling permits. 544.0 7 HANDLING . PBUs shall be handled, stored, and shipped in such a manner as to minimize chipping, cracks, fractures, discoloration, and excessive bending stresses. Units damaged by ha ndling, storage, or shipping shall be replaced at the Contractor’s expense. Field cured test cylinders for production site handling and shipping strength verification purposes shall be tested either at the Agency’s Materials Testing and Certification Section Central Laboratory or at an independent laborat ory approved by the Engineer. An Agency representative shall witness all tests. 5-337 If an independent lab is proposed to be used to test the field cured cylinders, the Contractor shall submit documentation p roviding verification for the following:
a.That calibration of the compression machine has been performed in accordance with ASTM C39, Section 5
b.That the compression machine meets the requirements of ASTM C39
c.That the technician who will be performing the test is proficient in the test methods The Agency at any time reserves the right to perform an independent proficiency of the technician for the test methods used and review of the testing facility. 544.0 8 INSTALLATION .
a.General Requirements . The PBUs shall be fabricated in accordance with the applicable section s of the specifications for each respective item. Construction procedures and p ermissible variations other than those contained herein shall be submitted for approval.
b.Erection Plan . Cranes, lifting devices, and other equipment for erecting PBUs shall be of adequate design and capacity to safely erect, align, and secure all membe rs and components in their final positions without damage. The Contractor is solely responsible for the methods and equipment employed for the erection of the PBUs. The Contractor shall submit construction draw ings in accordance with Subsection 105.06 for the methods and sequence of PBU erection, the temporary bracing, and the equipment to be used for the erection. The erection plan shall include the necessary computations to indicate the magnitude of stress in the segments during erection and to demonstrate that all of the erection equipment has adequate capacity for the work to be performed. The erection plan shall contain provisions for all stages of construction, including temporary stoppages. The PBUs may be used to support equipment prior to placement of the closure pour concrete only with written permission of the Engineer. The proposed use of the PBUs for support of equipment shall be detailed in the erection plan. Submittal of the erect ion plan is for documentation purposes only and shall in no way be construed as approval of the proposed method of erection. Unless otherwise directed by the Engineer, the Contractor shall follow the erection plan as submitted. 5-338 (c) Erection of Units . Erection of units shall not proceed until substructure concrete has been cured for the minimum length of time specified in the Plan s or appropriate specifications. Units shall be installed to the correct line and grade as shown on the approved drawings and as indicated in the approved erection procedure. Prior to setting units and to avoid torsion stresses, bearing elevations within a given PBU shall be adjusted to match relative elevations used during the deck cas ting operations. After all the units are erected, they shall be inspected to ensure the correctness of their location.
d.Matching Elevation of Units During Erection . Adjacent units shall match elevation within 1/4 inch vertically (along longitudinal edg es) and 1/4 inch vertically at the end of units.
e.Filling and Sealing Longitudinal Joints . Prior to the placement of closure pour concrete or grout material, the surface of the joint shall be free of any material, such as oil, grease, or dirt, which may prevent bonding of the sealing materials.
f.Sealing of Lifting Holes . After the units are in their final locations, a bonding agent shall be applied and the lifting holes filled with a Type IV mortar . A removable form shall be provided at the bottom su rface of the deck to retain the grout.
g.Loading . Units may be loaded upon erection and before the joints are sealed only with written permission of the Engineer and in accordance with the approved erection procedure. Once the joints are sealed, no further loading or unloading of the units will be allowed until the joint material has properly and finally cured and as approved by the Engineer.
h.Final Repairs . After the installation work is complete, remaining concrete defects, holes for inserts, and lifting holes shall be repaired as indicated and approved by the Engineer.
i.Grout . Grout shall be placed in accordance with the requirements of Subsection 540.11 . 544.0 9 METHO D OF MEASUREMENT . The quantity of Prefabricated Bridge Unit Superstructure to be measured for payment will be the number of linear feet installed in the complete and accepted work. Measurement will be the end -to-end length of the structural steel girder along the centerli ne per unit. 5-339 544.1 0 BASIS OF PAYMENT . The accepted quantity of Prefabricated Bridge Unit Superstructure will be paid for at the Contract unit price per linear foot. Payment will be full compensation for detailing, fabricating, repairing, quality con trol testing, transporting, handling, and installing the materials specified, including concrete, reinforcing steel, structural steel, shear connectors, mechanical connectors, and shims; for designing and installing lifting devices and any other material c ontained within or attached to the members; for any grouting work required; for furnishing and implementing the erection plan; and for furnishing all labor, tools, equipment, and incidentals necessary to complete the work. Payment will be made under: Pay Item Pay Unit
544.10 00 Prefabricated Bridge Unit Superstructure ................................ ................. Linear Foot
5-340 SECTIO N 546 – PRE-EXCAVATIO N OF ABUTMEN T PILES 546.0 1 DESCRIPTION . This work shall consist of drilling a hole to remove all subsurface material and backfilling in designated areas to provide suitable pile placement or driving conditions. 546.0 2 MATERIALS . Materials shall meet the requirements of the following subsect ions: Sand Borrow and Cushion ................................ ................................ ......................... 703.03 546.0 3 CONSTRUCTIO N REQUIREMENTS . The pre -excavation of abutment piles shall consist of augering, pre -boring, or some other means of excavation to produce an excavation to the depth and diameter specified in the Cont ract. The excavation shall be maintained to allow for backfilling with sand in accordance with the Contract . Temporary casing will be considered an acceptable option. Unless otherwise specified in the Plan s, the entire pre -excavation shall be filled with sand and the temporary casing shall be removed prior to installing piles. 546.0 4 DEFINITIONS .
a.Earth . In addition to the definition of earth in Subsection 101.02 , cobbles, boulders, and densely packed gravel will be considered excavation of earth.
b.Rock . All excavation of bedrock as determined by the Engineer. 546.0 5 METHO D OF MEASUREMENT . The quantities of Pre -Excavation of Abutment Piles, Earth and Pre-Excava tion of Abutment Piles, Rock to be measured for payment will be the total number of linear feet of excavation to the depth specified in the Contract or as ordered by the Engineer, measured to the nearest linear foot.
a.Earth . Where Structure Excavation and Pre -excavation of Abutment Piles, Earth occur jointly or separately at the same location, measurement for Pre -excavation of Abutment Piles, Earth will be made only below the lower limits of Structure Excavation.
b.Rock . The quantity of Pre -excavation of Abutment Piles, Rock to be measured for payment will be below the top surface of bedrock as determined by the Engineer.
Source: Vermont Standard Specifications for Construction, 2024 Edition. Pages 746–753 of 1,380.