B741 - TEMPORARY CONCRETE BARRIERS - OPSS 741

Transcription

1 B OPSS GENERAL Temporary concrete barrier (TCB) is a portable barrier system consisting of freestanding precast concrete segments that are positively connected together to form a continuous barrier system. Policies and descriptions for the various types of TCB systems accepted for use and specified on provincial highway projects are provided in the Roadside Design Manual. The systems are designed and crash tested for placement on paved surfaces, and paved surfaces should extend at least one metre beyond the back of unrestrained TCB systems TCB Restraint Systems TCBs are often used to provide separation between traffic and work zones, or at the edge of bridge decks. In locations where the offset from back of TCB to edge of excavation, edge of structure, scaffolding, temporary protection (support) system or sign support is less than one metre, it may be necessary to restrain the barrier to minimize deflection. Restraining details have been successfully crash tested to NCHRP Report 350 TL-3 for the Type M TCB. The three restraint systems acceptable for use in MTO contracts include the following: 1) Pinning to asphalt pavement (or concrete); 2) Strapping to concrete pavement or bridge deck (with or without asphalt overlay); 3) Bolting through concrete bridge deck (with or without asphalt overlay) Only the TCB Type M connection should be used with restraint systems. Unrestrained TCB should be transitioned to restrained TCB as shown on the applicable OPSD. Similarly, unrestrained TCB should be transitioned to permanent concrete barrier as shown on the applicable OPSD. The three TCB Restraint System tender items cover only the supply, installation, and removal of the restraint system. Temporary Concrete Barrier and Temporary Concrete Barrier, Relocation tender items are computed separately. Designers should refer to Roadside Design Manual for guidance on when to restrain TCB. January 2018 Page 1 of 5 CDED B741

2 TCB, Reduced Deflection System In locations where the offset from back of TCB to edge of excavation, edge of structure, scaffolding, temporary protection (support) system or sign support is less than one metre, the reduced deflection TCB may be used instead of the restrained system. The Type X TCB does not require any restraint systems and has been successfully crash tested to NCHRP Report 350 TL-3 and AASHTO MASH TL-3. Only the Type X TCB should be used for reduced deflection TCB and transitions to freestanding TCB as shown on the applicable MTODs REFERENCES Roadside Design Manual TENDER ITEMS Temporary Concrete Barrier Temporary Concrete Barrier, Relocation Temporary Concrete Barrier, Drainage Gap Temporary Concrete Barrier Restraint System, Pinned Temporary Concrete Barrier Restraint System, Strapped Temporary Concrete Barrier Restraint System, Bolted Temporary Concrete Barrier, Reduced Deflection Temporary Concrete Barrier, Reduced Deflection, Relocation (Normal, each, PQP) The tender item "Temporary Concrete Barrier" is used for the following work: a) Supplying and transporting the barriers to the site; b) The initial installation and including any additional barriers required for subsequent staging; and c) Removal of barriers after construction has been completed. The tender item "Temporary Concrete Barrier, Relocation" is used for the following work: a) Relocating the barriers within the work area as required for staging or seasonal shutdown for carryover projects; and b) The temporary storage of barriers at the site or other designated locations as necessitated by staging or seasonal shutdown for carryover projects. January 2018 Page 2 of 5 CDED B741

3 741.4 SPECIFICATIONS The requirements for TCBs and TCB restraint systems are contained in OPSS SPECIAL PROVISIONS Refer to Chapter 'E' of this Manual to review the applicable standard special provisions. Non-standard special provisions are required to specify and provide payment for: TCB that is to remain on a project upon its completion; The identification of specific temporary storage sites for TCB that cannot be accommodated within the project limits during staging or seasonal shutdown on carryover projects; and Restoration of asphalt and concrete surfaces that are disturbed during the installation and removal of TCB restraint systems STANDARD DRAWINGS Applicable standard drawings are contained in the 900 series of the Ontario Provincial Standards Drawings (OPSD) and 900 series of the Ministry of Transportation Ontario Drawings (MTOD) DESIGN TCB should be used on a paved surface, such as asphalt or concrete. TCB drainage gaps should only be used when justified based on the results of a hydraulic analysis. Prior to the 60% completion stage of detail design, the designer should send to the Ministry s Design and Contract Standards Office and Bridge Office the proposed location and quantity of TCB restraint systems along with a typical section(s) showing lane widths, shoulder widths, and offset of the TCB to edge of the excavation or structure. In constrained areas where it is necessary to reduce the width of the level area behind the TCB to the upper edge of each wall of an excavation or temporary protection (support) system to less than one metre, an Engineer shall design and provide January 2018 Page 3 of 5 CDED B741

4 documentation according to the Policies in the Roadside Design Manual, for use during construction according to Ontario Regulation 213/ COMPUTATION These are Plan Quantity Payment items. Quantities are computed in metres. Measurements are scaled or measured along the centreline of each installation. The unit of measurement for TCB drainage gaps is each complete installation. Transitions from restrained TCB to unrestrained TCB are included in the computed length for the appropriate TCB restraint system. Transitions from reduced deflection TCB to unrestrained TCB are included in the computed length for reduced deflection TCB. When a transition from unrestrained TCB to permanent concrete barrier is included in the contract, the length of the transition is included in the computed length for the appropriate TCB restraint system DOCUMENTATION TCBs are depicted on the contract drawings with the designation TCB or TCB Relocation shown adjacent to the symbol. Detail the station and offset for the start and end of each change in direction and/or offset of TCB. Show the locations of the TCB drainage gaps on the contract drawings with the OPSD reference and station shown adjacent to the symbol. Temporary Concrete Barrier - This item pays for the supply of the precast units, the total cannot exceed the largest number of units in place at any one time during the contract. Measurement is from end to end of all locations, restrained and unrestrained. Temporary Concrete Barrier, Relocation - This item will be comprised of all relocations during the contract. Measurement is from end to end of each individual relocation. Temporary concrete barrier lengths, temporary concrete barrier, relocation lengths, temporary concrete barrier, reduced deflection lengths, and temporary concrete barrier, reduced deflection, relocation lengths are computed and entered on the Quantities-Miscellaneous" sheets, showing station to station and location, left or January 2018 Page 4 of 5 CDED B741

5 right of centreline. Provide offsets if required. For contracts that include multiple construction stages, the quantities shall be broken down by each individual stage. Enter each TCB drainage gap installation in the Quantities Miscellaneous sheets as a separate line entry under the appropriate column heading showing station and location, left or right of centreline. Provide offsets if required. For contracts that include multiple construction stages, the quantities shall be broken down by each individual stage. TCB restraint system locations are depicted on the contract drawings with the appropriate OPSD number shown adjacent to the symbol. The limits of restraint shall be clearly indicated. The applicable standard drawings shall be included in the contract. TCB restraint system lengths are computed and entered on the Quantities- Miscellaneous" sheets under the appropriate column heading, showing station to station and location, left or right of centreline. Provide offsets if required. Total each column and transfer the tender totals to the tender document. For contracts that include multiple construction stages, the quantities shall be broken down by each individual stage. Reduced deflection TCB system lengths are depicted on the contract drawings with the designation TCB-RD shown adjacent to the TCB symbol. The minimum 32 m long transitions required on each end of the TCB-RD system are depicted with the designation TCB-RD-T shown adjacent to the TCB symbol. Detail the station and offset for the start and end of each change in direction and/or offset of TCB-RD and TCB-RD-T Documentation Accuracy Station and quantity entries are recorded to the nearest whole metre. Offsets when required are recorded to 0.1 of a metre. Spot checking required. January 2018 Page 5 of 5 CDED B741