B741 TEMPORARY CONCRETE BARRIERS - OPSS 741

Transcription

1 B741 TEMPORARY S - OPSS GENERAL Temporary concrete barriers (TCBs) are precast units that are installed with interlocking devices connecting consecutive sections. The following types of connections are acceptable for use on roadways with posted speeds less than 70 km/h: I-Lock Type J Type M Type T The following types of connections are acceptable for use on roadways with posted speeds of 70 km/h and greater: Type J Type M Type T The contractor shall select the type of TCB according to the specification and applicable special provisions TCB Restraint Systems TCBs are often used to provide separation between traffic and work zones. In locations where inadequate offset is available to allow for deflection of the TCBs (e.g. at edges of excavations, edges of structures, or adjacent to structures not designed for impacts), 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 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 shall be used with restraint systems. February 2014 Page 1 of 5 B741

2 Unrestrained TCB shall be transitioned to restrained TCB as shown on the applicable OPSD. Similarly, unrestrained TCB shall 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 the Roadside Safety Manual for guidance on when to consider restraining TCB REFERENCES Roadside Safety Manual Highway Design Bulletin 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 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. February 2014 Page 2 of 5 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) DESIGN TCB drainage gaps shall only be used when warranted based on the results of a hydraulic analysis. Prior to the 60% completion stage of detail design, the designer shall 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 COMPUTATION These are Plan Quantity Payment items. Quantities are computed in metres. Measurements are scaled or measured along the centreline of each installation. February 2014 Page 3 of 5 B741

4 The turned down and/or flared end treatment is included in the computed length. Energy attenuators are not included in the computed length. 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. 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 including end sections. 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, including end sections. Temporary concrete barrier and temporary concrete barrier, relocation lengths are computed and entered on the Quantities-Miscellaneous" sheets, showing station to 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. 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 February 2014 Page 4 of 5 B741

5 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 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. February 2014 Page 5 of 5 B741