M 41-10 Page 6-2276-12 Noise Barrier Walls
6-12.1 Description
This Work consists of constructing cast-in-place concrete, precast concrete, masonry, and timber noise barrier walls, including those shown in the Standard Plans .
6-12.2 Materials
Materials shall meet the requirements of the following sections: Cement 9-01 Aggregates for Concrete 9-03.1 Gravel Backfill 9-03.12 Premolded Joint Filler 9-04.1(2 ) Bolts, Nuts, and Washers 9-06.5(1) Noise Barrier Wall Access Door 9-06.17 Steel Reinforcing Bar 9-07.2 Epoxy-Coated Steel Reinforcing Bar 9-07.3 Paints 9-08 Grout 9-20.3 Concrete Curing Materials and Admixtures 9-23 Fly Ash 9-23.9 Water 9-25 Other materials required shall be as specified in the Special Provisions.
6-12.3 Construction Requirements
6-12.3(1) Submittals
All noise barrier walls not constructed immediately adjacent to the Roadway, and that require construction of access for Work activities, shall have a noise barrier wall access plan. The Contractor shall submit a Type 2 Working Drawing consisting of the noise barrier wall access plan. The noise barrier wall access plan shall include, but not be limited to, the locations of access to the noise barrier wall construction sites, and the method, materials, and equipment used to construct the access, remove the access, and recontour and reseed the disturbed ground. For construction of all noise barrier walls with shafts, the Contractor shall submit a Type 2 Working Drawing consisting of the shaft construction plan, including at a minimum the following information:
1.List and description of equipment to be used to excavate and construct the shafts, including description of how the equipment is appropriate for use in the expected subsurface conditions.
2.The construction sequence and order of shaft construction.
3.Details of shaft excavation methods, including methods to clean the shaft excavation.
4.Details and dimensions of the shaft, and casing if used.
5.The method used to prevent ground caving (temporary casing, slurry, or other means).
6.Details of concrete placement including procedures for deposit through a conduit, tremie, or pump.
7.Method and equipment used to install and support the steel reinforcing bar cage. Noise Barrier Walls 6-12 Page 6-228 M 41-10For construction of precast concrete noise barrier walls, the Contractor shall submit Type 2 Working Drawings consisting of shop drawings for the precast concrete panels in accordance with Section 6-02.3(9)A . In addition to the items listed in Section 6-02.3(9)A , the precast concrete panel shop drawings shall include the following:
1.Construction sequence and method of forming the panels.
2.Details of additional reinforcement provided at lifting and support locations.
3.Method and equipment used to support the panels during storage, transporting, and erection.
4.Erection sequence, including the method of lifting the panels, placing and adjusting the panels to proper alignment and grade, and supporting the panels during bolting, grouting, and backfilling operations. The Contractor shall not begin noise barrier wall construction activities, including access construction and precast concrete panel fabrication, until receiving the Engineer’s approval of all appropriate and applicable submittals.
6-12.3(2) Work Access and Site Preparation
The Contractor shall construct Work access in accordance with the Work access plan. The construction access roads shall minimize disturbance to the existing vegetation, especially trees. Only trees and shrubs in direct conflict with the approved construction access road alignment shall be removed. Only one access road into the noise barrier wall from the main Roadway and one access road from the noise barrier wall to the main Roadway shall be constructed at each noise barrier wall. Existing vegetation that has been identified by the Engineer shall be protected in accordance with s 1-07.16 and 2-01 , and the Special Provisions.
6-12.3(3) Shaft Construction
The Contractor shall excavate and construct the shafts in accordance with the shaft construction plan. The shafts shall be excavated to the required depth as shown in the Plans. The excavation shall be completed in a continuous operation using equipment capable of excavating through the type of material expected to be encountered. If the shaft excavation is stopped, the Contractor shall secure the shaft by installing a safety cover over the opening. The Contractor shall ensure the safety of the shaft and surrounding soil and the stability of the side walls. A temporary casing, slurry, or other methods acceptable to the Engineer shall be used as necessary to ensure such safety and stability. When caving conditions are encountered, the Contractor shall stop further excavation until implementing the method to prevent ground caving as specified in the shaft construction plan. When obstructions are encountered, the Contractor shall notify the Engineer promptly. An obstruction is defined as a specific object (including, but not limited to, boulders, logs, and man made objects) encountered during the shaft excavation operation, which prevents or hinders the advance of the shaft excavation. When efforts to advance past the obstruction to the design shaft tip elevation result in the rate of advance of the shaft drilling equipment being significantly reduced relative to the rate of advance for the rest of the shaft excavation, then the Contractor shall remove the obstruction under the provisions of Section 6-12.5 . The method of removal of such obstructions, and the continuation of excavation shall be as proposed by the Contractor and accepted by the Engineer.
6-12 Noise Barrier Walls
M 41-10 Page 6-229The Contractor shall use appropriate means to clean the bottom of the excavation of all shafts. No more than 2 inches of loose or disturbed material shall be present at the bottom of the shaft just prior to beginning concrete placement. The Contractor shall not begin placing steel reinforcing bars and concrete in the shaft until receiving the Engineer’s acceptance of the shaft excavation. The steel reinforcing bar cage shall be rigidly braced to retain its configuration during handling and construction. The Contractor shall not place individual or loose bars. The Contractor shall install the steel reinforcing bar cage as specified in the shaft construction plan. The Contractor shall maintain the minimum concrete cover shown in the Plans. If casings are used, the Contractor shall remove the casing during concrete placement. A minimum 5-feet head of concrete shall be maintained to balance soil and water pressure at the bottom of the casing. The casing shall be smooth. Where the top of the shaft is above the existing ground, the Contractor shall case the top of the hole prior to placing the concrete. Concrete for shafts shall conform to Class 4000P. The Contractor shall place concrete in the shaft immediately after completing the shaft excavation and receiving the Engineer’s acceptance of the excavation. The Contractor shall place the concrete in one continuous operation to the elevation shown in the Plans, using a method to prevent segregation of aggregates. The Contractor shall place the concrete as specified in the shaft construction plan. If water is present, concrete shall be placed in accordance with Section 6-02.3(6)B .
6-12.3(4) Trench, Grade Beam, or Spread Footing Construction
Where the noise barrier wall foundations exist below the existing ground line, excavation shall conform to Section 2-09.3(4) , and to the limits and construction stages shown in the Plans. Foundation soils found to be unsuitable shall be removed and replaced in accordance with Section 2-09.3(1)C . Where the noise barrier wall foundations exist above the existing ground line, the Contractor shall place and compact backfill material in accordance with Section 2-03.3(14)C . Concrete for trench, grade beam, or spread footing foundations shall conform to Class 4000. Cast-in-place concrete shall be formed, placed, and cured in accordance with Section
6-02 , except that concrete for trench foundations shall be placed against undisturbed
soil. Cast-in-place footings shall have a longitudinal slope no steeper than 1V: 6H, unless otherwise shown in the Plans or Standard Plans . The excavation shall be backfilled in accordance with item 1 of the Compaction Subsection of Section 2-09.3(1)E . The steel reinforcing bar cage and the noise barrier wall anchor bolts shall be installed and rigidly braced prior to grade beam and spread footing concrete placement to retain their configuration during concrete placement. The Contractor shall not place individual or loose steel reinforcing bars and anchor bolts, and shall not install anchor bolts during or after concrete placement.
6-12.3(5) Cast-In-Place Concrete Panel Construction
Construction of cast-in-place concrete panels for noise barrier walls shall conform to Section 6-11.3(4) . For noise barrier walls with traffic barrier, the construction of the traffic barrier shall also conform to Section 6-10.3(2) . The top of the cast-in-place concrete panels shall conform to the top of wall profile shown in the Plans. Where a vertical step is constructed to provide elevation change between adjacent panels, the dimension of the step shall be 2 feet. Each horizontal run between steps shall be a minimum of 48 feet. Noise Barrier Walls 6-12 Page 6-230 M 41-106-12.3(6) Precast Concrete Panel Fabrication and Erection The Contractor shall construct the precast concrete panels in accordance with Section
6-02.3(9) , and the following requirements:
1.Concrete shall conform to Class 4000.
2.Except as otherwise noted in the Plans and Special Provisions, all concrete surfaces shall receive a Class 2 finish in accordance with Section 6-02.3(14)B .
3.The Contractor shall fully support the precast concrete panel to avoid bowing and sagging surfaces. After receiving the Engineer’s review of the shop drawings, the Contractor shall cast one precast concrete panel to be used as the sample panel. The Contractor shall construct the sample panel in accordance with the procedure and details specified in the shop drawings. The Contractor shall make the sample panel available to the Engineer for acceptance. Upon receiving the Engineer’s acceptance of the sample panel, the Contractor shall continue production of precast concrete panels for the noise barrier wall. All precast concrete panels will be evaluated against the quality of the accepted sample panel. The sample panel shall be retained at the fabrication site until all precast concrete panels have been fabricated and accepted. After completing precast concrete panel fabrication, the Contractor may utilize the sample panel as a production noise barrier wall panel.
4.In addition to the fabrication tolerance requirements of Section 6-02.3(9) , the precast concrete panels for noise barrier walls shall not exceed the following scalar tolerances: Length and Width: ± ⅛ inch per 5 feet, not to exceed ¼ inch total. Thickness: ± ¼ inch. The difference obtained by comparing the measurement of the diagonal of the face of the panels shall not be greater than ½ inch. Dimension tolerances for the traffic barrier portion of precast concrete panels formed with traffic barrier shapes shall conform to Section 6-10.3(2) .
5.Precast concrete panels shall not be erected until the foundations for the panels have attained a minimum compressive strength of 3,400 psi.
6.The bolts connecting the precast concrete panels to their foundation shall be tightened to “snug tight” as defined in Section 6-03.3(32) .
7.After erection, the precast concrete panels shall not exceed the joint space tolerances shown in the Plans. The panels shall not exceed ⅜ inch out of plumb in any direction. The Contractor shall seal the joints between precast concrete panels with a backer rod and sealant system as specified. The Contractor shall seal both sides of the joint full length. The top of precast concrete panels shall conform to the top of wall profile shown in the Plans. Where a vertical step is constructed to provide elevation change between adjacent panels, the dimension of the step shall be 2 feet. Each horizontal run between steps shall be a minimum of 48 feet.
6-12.3(7) Masonry Wall Construction
Construction requirements for masonry noise barrier wall panels shall be as specified in the Special Provisions.
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M 41-10 Page 6-2316-12.3(8) Fabricating and Erecting Timber Noise Barrier Wall Panels Construction requirements for timber noise barrier wall panels shall be as specified in the Special Provisions.
6-12.3(9) Access Doors and Concrete Landing Pads
The Contractor shall install access doors and door frames as shown in the Plans and Standard Plans . The Contractor shall install the access doors to open toward the Roadway side. The door frames shall be set in place with grout conforming to either Section
9-20.3(2) or 9-20.3(4) and placed in accordance with Section 6-02.3(20) , with the grout
completely filling the void between the door frame and the noise barrier wall panel. All door surfaces shall be painted in accordance with Section 6-07.3(9) except that primer shall be applied by the steel sheet supplier using methods and paint system as recommended by the manufacturer. Primer shall be compatible with the remaining coats as specified in Section 6-07.3(9) . All primer coated exposed metal surfaces shall be field painted with the remaining Section 6-07.3(9)A paint system coats. The top coat, when dry, shall match the color specified in the Plans or Special Provisions. The Contractor shall construct concrete landing pads for each access door location as shown in the Plans. The concrete shall conform to Section 6-02.3(2)B . Access door deadbolt locks shall be capable of accepting a Best CX series core. The Contractor shall furnish and install a spring-loaded construction core lock with each lock. The Engineer will furnish the permanent Best CX series core for the Contractor to install at the conclusion of the project.
6-12.3(10) Finish Ground Line Dressing
The Contractor shall contour and dress the ground line on both sides of the noise barrier wall, providing the minimum cover over the foundation as shown in the Plans. The Contractor shall contour the ground adjacent to the barrier to ensure good drainage away from the barrier. After the access roads are no longer needed for noise barrier wall construction activities, the Contractor shall restore the area to the original condition. The Contractor shall recontour the access roads to match into the surrounding ground and shall reseed all disturbed areas in accordance with the Section 8-01 and the Special Provisions, and the noise barrier wall access plan.
6-12.4 Measurement
Noise barrier wall will be measured by the square foot area of one face of the completed wall panel in place. Except as otherwise noted, the bottom limit for measurement will be the top of the trench footing, spread footing, or shaft cap. For Noise Barrier Type 5, the bottom measurement limit will be the optional construction joint at the base of the traffic barrier. For Noise Barrier Type 7, the bottom measurement limit will be base of the traffic barrier. For Noise Barrier Types 8, 11, 12, 14, 15, and 20, the bottom measurement limit will be the base of the wall panel. Noise barrier wall access door will be measured once for each access door assembly with concrete landing pad furnished and installed. Noise Barrier Walls 6-12 Page 6-232 M 41-106-12.5 Payment Payment will be made for each of the following Bid items when they are included in the Proposal: “Noise Barrier Wall Type __”, per square foot. The unit Contract price per square foot for “Noise Barrier Wall Type __” shall be full pay for constructing the noise barrier walls as specified, including constructing and removing access roads, excavating and constructing foundations and grade beams, constructing cast-in-place concrete, and masonry wall panels, fabricating and erecting precast concrete, and timber wall panels, applying sealer, and contouring the finish ground line adjacent to the noise barrier walls. “Noise Barrier Wall Access Door”, per each. The unit Contract price per each for “Noise Barrier Wall Access Door” shall be full pay for furnishing and installing the access door assembly as specified, including painting the installed access door assembly and constructing the concrete landing pads. “Removing Noise Barrier Wall Shaft Obstructions”, estimated. Payment for removing obstructions, as defined in Section 6-12.3(3) , will be made for the changes in shaft construction methods necessary to remove the obstruction. The Contractor and the Engineer shall evaluate the effort made and reach agreement on the equipment and employees utilized, and the number of hours involved for each. Once these cost items and their duration have been agreed upon, the payment amount will be determined using the rate and markup methods specified in Section 1-09.6 . For the purpose of providing a common proposal for all bidders, the Contracting Agency has entered an amount for the item “Removing Noise Barrier Wall Shaft Obstructions” in the bid proposal to become a part of the total bid by the Contractor. If the shaft construction equipment is idled as a result of the obstruction removal work and cannot be reasonably reassigned within the project, then standby payment for the idled equipment will be added to the payment calculations. If labor is idled as a result of the obstruction removal work and cannot be reasonably reassigned within the project, then all labor costs resulting from Contractor labor agreements and established Contractor policies will be added to the payment calculations. The Contractor shall perform the amount of obstruction work estimated by the Contracting Agency within the original time of the contract. The Engineer will consider a time adjustment and additional compensation for costs related to the extended duration of the shaft construction operations, provided:
1.The dollar amount estimated by the Contracting Agency has been exceeded, and;
2.The Contractor shows that the obstruction removal work represents a delay to the completion of the project based on the current progress schedule provided in accordance with Section 1-08.3 .
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Source: Washington Standard Specifications for Road, Bridge, and Municipal Construction, 2024 Edition. Pages 581–586 of 1,151.