Frequently asked questions
Why weave the lower ropes?
To provide a system dynamic deflection that is not unduly affected by length between anchorages, straight rope systems being prone to high deflection characteristics when long fence length.
What s the minimum horizontal and vertical curve radius?
The minimum radius of installation on horizontal curves is 200m, however, an arrangement of strategically placed intermediate anchorages can be incorporated in the scheme design to allow tighter radii to be handled. The minimum vertical sagging curve radius is 3 kilometers.
Does post spacing affect deflection?
Yes, the dynamic deflection will be reduced when small post spacings ( 1m minimum) are used, and increase to a maximum when a post spacing of 3.2m or greater is used.
What is the minimum and maximum fence length?
The minimum length of fence installed on High Speed roads at full height is 40m, but there is a requirement to provide tested Terminal sections of up to 26.8m each in length at each end of the fence section. There is no fixed maximum length, but crossover sections or intermediate anchorages may be desirable on certain schemes for convenience of layout.
Can the fence work in all temperatures?
Yes , but in very cold climates special attention will need to be given to anchorage block sizes, particularly in poor soil conditions. In hot weather conditions where rope temperatures are in excess of 40 deg C Brifen will advise the appropriate tensioning practice to be adopted.
After an impact , do you need to replace the rope?
It is not normally necessary after car impacts, unless any of the individual wires are broken or severely thinned . Goods vehicle impacts may be expected to give more damage, however.
Does rope stretch or lose tension over time?
The rope is prestressed to minimize loss of tension of a system, but some tension checking is advised, in accordance with the Maintenance Manual.
Does the rope act as a “Cheesewire” on Motorcyclists?
No known cases officially reported of this happening with Brifen; the primary danger for Motorcyclists who fall from their machines is the intermediate posts; this is true for all post and Beam Safety Fences. A suitable motorcycle rider protection system has been installed on Brifen and we can advise on this.
Is it vandal proof?
Brifen rope is under high tension and cannot safely be dismantled without the use of special tools.
Can Brifen connect to other systems?
Yes, it can connect to other metal Safety fences by use of tested Transition units.