Answer: They must be flagged with highly visible materials at least every six feet
Explanation:
If wire rope guardrails are used, then they must be flagged. It is a standard practice to use highly visible material every six feet for best visibility. This practice should be followed, so that the chances of accidents can be lowered.
Moreover, the Wire rope guardrails used should be capable of withstanding a weight of 200 pounds. For its proper installation, adequate amount of clips should be used to make sure that the wire will not snap.