WIRE ROPE SAFETY FENCE
SPECIFICATION FOR BRIFEN WIRE ROPE SAFETY FENCE
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General Requirements |
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Description of Components |
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Component Manufacturing Requirements |
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Installation |
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List of European & National Standards |
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Drawings |
A.4 INSTALLATION
Excavations
1. Excavations for concrete post
foundations and anchor blocks shall have vertical sides and shall be formed to the line and level described in
the drawings.
Post Foundations and Anchor Blocks
2. Precast concrete post foundations
shall be installed on a firm level base. Any lateral overbreak of the excavations shall be filled with grade C7.5P
concrete.
3. In-situ
concrete post
foundations and anchor blocks shall be constructed using 25 MPa concrete to grade C25P and BS 5328. Temporary formwork
shall be used where the sides of excavations cannot be kept vertical for in-situ concrete post foundations and
anchor blocks. The formwork shall be installed immediately after the excavation. Any lateral overbreak of the excavation
shall be filled with concrete.
4. All anchor frames, posts, sockets
and reinforcing rings shall be positioned to the line and levels described in the drawings and they shall be secured
against displacement during placing of the concrete.
5. Concrete shall be compacted
using internal vibration and shall be thoroughly worked around any embedded metal and into corners of formwork
or excavations to produce a dense mass substantially free from voids and in such a manner as to prevent segregation.
Immediately on completion of compaction exposed surfaces shall be covered for a minimum period of 7 days (unless
the Engineer agrees a shorter period) by covering with a impermeable sheeting set to prohibit excess of moisture.
The sheeting shall be removed at the end of the curing period. Formwork shall be struck without damage to the concrete
not less than 7 days after placing the concrete. Formed and unformed surfaces shall be free from voids, honeycombing
and other defects. Small blemishes caused by entrapped air or water are acceptable.
Posts
6. Posts shall be installed so
that:
- The alignment on plan of the completed fence does not deviate by more than +/- 30mm at any point from that detailed in the drawings.
- The alignment in elevation of the tops of the fence posts do not deviate in any 10m length by more than +/- 10mm form that detailed in the Contract;
- The radiused edges of the posts are presented to the direction of the traffic flow.
7. Driven line posts shall be installed
to the levels detailed in the drawings without damage to the slot in the top of the post.
8. Surface mounted post shall
be installed in accordance with the details given in the drawings.
9. No drilling, cutting or welding
of posts shall be permitted without the prior approval of the Engineer. Excluders shall be fitted on all line posts
installed in the sockets.
Loading Tests of Post Foundations
10. Where directed by the Engineer,
loading tests will be carried out on post foundations installed by the Contractor. Details of the locations where
testing will be required, the foundation type and the number of foundations to be tested will be given by the Engineer.
11. Unless otherwise agreed by
the Engineer, the Contractor shall install the posts and foundations required for tests prior to installation of
the relevant length of safety fence and after completion of the tests, the Contractor shall remove the test posts
and foundations and reinstate the earthworks unless otherwise directed by the Engineer.
12. The Contractor shall establish
and maintain all necessary traffic management procedures and safety measures during installation, test loading
and removal of the test posts and foundations.
Ropes
13. The ropes shall be installed
to the layouts shown on the contract drawings, also to Drawings LB/01, LB/07, LB/11, LB/12, LB/13 and to the following
requirements.
- The two lower line ropes shall be placed on the hooks of each deflection post, interwoven between successive line posts and finally positioned on the locating pegs of each line post;
- The two upper line ropes shall be placed in the slot of each post;
- Ropes shall be joined by rigging screws with a thread engagement of not less than 25mm;
- One end of each tail rope shall be connected to an anchor frame in the anchor block and shall be fitted with a safety check rope which shall be connected to the attachment plate;
- The length of line rope between any anchors shall be not greater than 1385m.
- Two ropes, one upper and one lower, shall be terminated at each intermediate anchor, for a four rope system.
Tensioning
14. All rigging screws on each
line rope shall be adjusted equally to achieve the tension given in Table A appropriate to the ambient temperature,
which shall be agreed with the Engineer. The tension in each rope shall not deviate along its length by more than
+/- 0.5kN from the agreed tension, at the time of installation measured using a tension indicating device approved
by the Engineer.
15. Prior to putting the safety
fence into service the tension in each rope shall be checked and shall be retensioned if necessary to comply with
the requirements of Table A.
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Ambient Temperature |
Rope Tension |
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-10 |
36.0 |
Table A
Relationship Between Rope Tension and Ambient Temperature
Specification Index
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