604 CONCRETE TRAFFIC BARRIERS
- Construct concrete traffic barriers.
Crusher Run Aggregate CR-6 901.01 Aggregate 901.01, Size No. 57 Curing Materials 902.07 Form Release Compound 902.08 Portland Cement Concrete 902.10, Mix No. 3 Portland Cement Concrete 902.10, Mix No. 6 PVC Pipe 905 Reinforcement Steel 908 Preformed Joint Fillers 911.02 Borrow Excavation 916.01 Geotextile 919 Reflective Delineators QPL
- Use concrete mix No. 6 to construct all concrete traffic barriers, end transitions, and footers unless otherwise specified. Before beginning work, construct a sample panel approximately 2 ft x 2 ft x 3 in. using the proposed concrete mix design. After 28 days, the concrete shall match Federal Standard No. 595, Color 37722 or lighter. Submit the panel and mix design to the Office of Materials Technology for approval. Keep the approved sample panel at the construction site to be used by the EngineerAny person designated by the Administrator or the procurement officer, acting directly or through his duly authorized representative, such representative acting within the scope of the particular duties assigned to him or of the authority given him. to compare the color of the concrete barrier to the sample panel for adjustments and approval.
- Submit a sample panel for each source of supply.
- Use cast-in-place construction. Excavate to the required depth and to a width that will permit the installation and bracing of forms where necessary. Remove all soft and unsuitable material, and replace it with suitable material. Properly shape the subgrade and compact it as specified in Section 208.
- 604.03.01 Concrete Barriers. Forming of the footer or concrete barrier may be by either the fixed form or the slip-form method. Do not construct the footer and the barrier section monolithically.
- (a) Fixed Form Method. Use steel forms with a tolerance in grade and alignment of 1/4 in. in 10 ft. For bifurcated and transition sections, other forming materials may be used as directed.
- Thoroughly clean and coat the forms with form release compound each time they are used.
- Saw or form construction and contraction joints at 20 ft intervals with a minimum of 10 ft. For saw time requirements, refer to 520.03.14(c)(1). Place expansion joints where specified or as directed. Ensure that all joints in footers and walls align.
- Finish concrete as specified in 604.03.03 except apply a broom finish to the surface when forms are stripped in less than 24 hours. Remove the face forms for finishing as soon as the concrete can retain its shape.
- After removing the forms, immediately repair all honeycombed and damaged areas.
- (b) Slip-form Method. Use approved slip-form equipment. The equipment shall have internal vibrating capability and automatic guidance controls to follow line and grade references. On vertical and horizontal curves, set an additional intermediate support in the field to establish an acceptable reference line. Do not use ski or shoe sensors. This method shall not be used within 5 ft. of either side of a utility junction box. Use the fixed form method.
- Mix concrete as specified in 915.03.04. Ensure that the consistency of the concrete after extrusion will maintain the shape of the barrier without support. Provide surfaces that are free of pits larger than 3/16 in. diameter and that require no further finishing other than a broomed finish.
- Whenever a tear occurs during the operation of the slip-form equipment, repair it immediately or remove and replace as directed.
- Saw or form construction and contraction joints at 20 ft intervals in the barrier and footer with a minimum of 10 ft, except in the area of miscellaneous structures 6 ft will be permitted. Saw the joints 1/8 in. wide and at least 2 in. deep. Place expansion joints as specified or as directed.
- 604.03.02 Curing. Cure and protect concrete as specified in Section 420.
- 604.03.03 Finished Surface. Finish concrete as specified in Section 420. The completed barriers shall be within 1/4 in. in 10 ft from the specified horizontal and vertical lines. The barrier shall present a smooth, uniform appearance.
- 604.03.04 Reflective Delineators. Install reflective delineators on the concrete traffic barrier as specified.
604.04 MEASUREMENT AND PAYMENT.
- The payment will be full compensation for all test panels, excavation, removal of existing asphalt mix, disposal of excess or unsuitable material, reinforcement, drilled holes, drainage appurtenances, geotextile, No. 57 aggregate, conduit, boxes and fittings, backfilling, and for all material, labor, equipment, tools, and incidentals necessary to complete the work.
- The removal and disposal of unsuitable material will be measured and paid for at the Contract unit price for Class 2 Excavation, which price includes the cost of using suitable excavation as replacement material. When Borrow or Selected Backfill is authorized as replacement material, payment will be made at the Contract unit price for the respective items.
- The removal of existing concrete traffic barriers will not be measured unless specified elsewhere in the Contract DocumentsThe written agreement executed between an Administration and the successful bidder, covering the performance of the work and furnishing of labor, equipment and materials, by which the Contractor is bound to perform the work and furnish the labor, equipment and materials, and by which the Administration is obligated to compensate him therefore at the mutually established and accepted rate or price. The Contract Documents shall include the Invitation for Bids, Notice to Contractors, Instructions to Bidders, Proposal, Contract Forms and Bonds, General Provisions, Specifications, Supplemental Specifications, all Special Provisions, all Technical Provisions, all Plans and Notices to Proceed, also any written Change Orders and Supplemental Agreements that are required to complete the construction of the work in an acceptable manner, including authorized extension thereof.
- 604.04.01 Concrete Traffic Barriers will be measured and paid for at the Contract unit price per linear foot. Measurement will be along the center line of the top of the barrier.
- 604.04.02 Concrete Traffic Barrier End Transitions will be measured and paid for at the Contract unit price per each.
- 604.04.03 Reflective Delineators will be measured and paid for at the Contract unit price per each.
SPECIAL PROVISION INSERTS
The following Special Provision Inserts update Section 604 after the official publication of the Standard SpecificationA written description of functional characteristics, or the nature of a construction item to be procured. It may include a. Updated documents may be found within the Standard and Supplemental Specifications for Construction and Materials on the MDOTMaryland Department of Transportation SHA web page.
- SPI-Section 604-Concrete Traffic Barriers. Dated 5/11/2018.