17Grids#
17.1General#
Clause 17 describes the work to be carried out where a grid is required to be installed under the contract.
17.2Fabrication#
Grid frames shall be fabricated to the details shown on Standard Drawings 1565, or an approved design in accordance with Technical Note 18 Design Criteria for Motor Grids.
All steel fabrication shall be carried out in accordance with the requirements of MRTS78 Fabrication of Structural Steelwork.
Components of grids shall be galvanised in accordance with the requirements of MRTS78 Fabrication of Structural Steelwork.
17.3Precast concrete#
Precast concrete components shall be manufactured in accordance with the relevant Standard Drawings or approved design and with the requirements of MRTS72 Manufacture of Precast Concrete Elements.
17.4Material requirements#
17.4.1Steel plate and sections#
Steel plate shall comply with the requirements of AS/NZS 3678 and shall be a minimum of Grade 250.
Rolled steel sections shall comply with the requirements of AS/NZS 3679.1 and shall be a minimum of Grade 300.
RHS section shall comply with the requirements of AS/NZS 1163 and shall be a minimum of Grade 450 LO. CHS sections for fencing shall comply with the requirements of AS/NZS 1163 and shall be a minimum of Grade 350 LO.
All materials shall be supplied in accordance with the requirements of MRTS78 Fabrication of Structural Steelwork.
17.4.2Bolts, nuts and washers#
Bolts shall conform to the requirements of AS 1111.1, nuts shall conform to the requirements of AS 1112.3 and flat washers shall conform to the requirements of AS 1237.1. Bolts, nuts and washers shall be hot-dipped galvanised in accordance with the requirements of AS/NZS 1214.
All fasteners comply with the requirements of MRTS278 Supply of Structural Fasteners.
17.4.3Included road furniture#
Guide posts shall conform to the requirements of Clause 10.
Hazard markers shall conform to the requirements of Clause 14.
Fencing shall conform to the requirements of Clause 11.
Gates shall conform to the requirements of Clause 12.
17.4.4Concrete#
Concrete shall conform to the requirements of MRTS70 Concrete. Precast concrete components shall be manufactured in accordance with MRTS72 Manufacture of Precast Concrete Elements.
17.4.5Steel reinforcing#
Steel reinforcing shall conform to the requirements of MRTS71 Reinforcing Steel.
17.4.6Cement mortar#
Cement mortar shall consist of one part of Type GP cement AS 3972 and three parts of clean, sharp sand with sufficient water added to form a dry packing mortar. Alternatively, a proprietary bagged mortar may be presented to the Administrator for approval.
17.5Construction#
17.5.1General#
The grades, sizes and shapes, as relevant, of the concrete structures, steel components, fixtures, fittings and related road furniture shall be shown on Standard Drawings 1353, 1354, 1355, 1561, 1562, 1563, 1564 and 1565. Grids shall be constructed to the dimensions and other details stated in Clause 9 of Annexure MRTS14.1.
17.5.2Excavation and backfilling#
Excavations shall be carried out in accordance with the requirements of MRTS04 General Earthworks. Where insitu material on or against which concrete abutments and/or slabs are to be constructed is other than rock, the material shall be compacted as for material at the bottom of excavations in accordance with the requirements stated in MRTS04 General Earthworks. Backfilling to abutments and wing walls shall be carried out using selected excavated material in accordance with the requirements stated in MRTS04 General Earthworks.
17.5.3Concrete work#
Concrete abutments and slabs shall be constructed without foundation bedding. Concrete shall be placed, compacted and finished in accordance with the requirements of MRTS70 Concrete. Steel reinforcing shall be placed in accordance with the requirements of MRTS71 Reinforcing Steel. Prior to placing the concrete, all holding-down bolt assemblies and bed rail, where required, shall be securely fixed into their final positions so that they are not displaced during placement of concrete.
17.5.4Precast components#
Precast components shall be installed as indicated on the certified Engineering drawings.
17.5.5Installation of grid frame#
The grid frame shall not be supported by the concrete abutments until three days after the placement of the concrete or until the concrete has reached 50% of the specified 28 day characteristic strength, whichever is the lesser.
17.5.6Installation of fencing#
Fencing shall be constructed in accordance with the details shown on Standard Drawings 1353 and 1561 and the requirements of Clause 11. Gates, where required, shall be installed in accordance with the details shown on Standard Drawing 1353 and to the requirements of Clause 12.
17.5.7Installation of road furniture#
Guide posts shall be installed in accordance with the requirements of Clause 10.
17.5.8Reinstatement#
Following construction of the grids, any disturbed pre-existing formation and/or pavement shall be reinstated to at least the same standard which existed prior to commencement of construction. Additionally, any pre-existing fencing shall be reinstated to at least the same standard which existed prior to commencement of construction.
17.5.9Trafficking of grid#
Traffic shall not use the grid until the specified 28 day characteristic strength has been achieved and seven days from placement have passed.