Another much less combersome way to meet the requirement and to speed the work is to use a retractable reel if circumstances permit. I've been on projects where the 100% tie off rule was a part of the contract language in addition to being an Osha rule, and it was strictly enforced.
Mark is right, if one unhooks from an anchorage point without having a second harness anchorage secure, there is a potential for a fall and the person in the harness has violated the 100% rule. The retractable reels fix that an allows for much more freedom of movement.
The retractable reels have improved greatly in the past few years. There are now lightweight models that are worn on the back of the harness at the D ring, so wherever the harness wearer travels, his retractable reel goes with him. I had up to 30-40 guys in harnesses with retractable reels recently on a bridge job and there was neary a complaint. The few subcontractor guys in double lanyards grumbled now and then, and I can see why; watching the guys in retractable reels vs the guys with double lanyards was night and day in terms of production, safety and effort.
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