I have recntly had to submit a report titled "fall arrest versus belay" for my department. This came as a result of heated discussions about which attachment point to use on the harness for the belay(safety)line. We have some which say we must use the dorsal attachment because of fall arrest legislation and some, myself included, who feel the dorsal is a dangerous option that must be used as a last resort. I have had this discussion with rescuers for years, however I learned a great deal while preparing this report about Canadian fall protection legislation. I wanted to share some of the main points with fellow rescuers because I also learned that there are a lot of teams using the dorsal attachment for belay.
When fall protection legislation was brought into place, there was no consideration given to the impact that such a vague document would have on various groups like rescuers and rope access workers. The problem with the laws is that while they do not specifically mention rescuers, they do not specifically recognize them as exempt. As a result of this rescuers have been forced to use fall arrest practices which are not as safe as the rope rescue practices that have been used safely for years.
The use of the dorsal attachment was the result of engineers and doctors looking at a worst case scenario fall for a worker using fall arrest equipment. This would be a worker using a 6 foot lanyard(no shock absorber) and anchoring it as low as possible before the fall.The worker would als be unconscious. The result is a 12 foot fall. On a 6 foot lanyard this results in a fall factor 2.(Fall Factor=free fall/ length of rope)A fall of this severity is in most cases fatal. The head is thrown violently in a fall like this and they felt that by using the dorsal it would minimize the whiplash hazard as the head will only go forward until the chin hits the chest. The part that was ignored in the study was the fact that the doctor(Dr. M. Amphoux) stated that if fall distance and impact were minimized sternal attachment would be acceptable.If you look at a typical rope rescue incident you can figure out the worst case scenario. This would be when the rope is shortest which would be when the rescuer is first being lowered over the edge. At this point the length of rope in the belay is at least 10 feet. The slack in the belay at this point is , at worst, 1 foot. On my team 1 foot of slack would be unnacceptable but I am over estimating to show the great difference in the two techniques. The resulting fall factor in this case would be 0.1, a fraction of what is seen in fall arrest.
There have been numerous studies over the years on harness induced suspension trauma. All of these studies stress the importance of being able to take the weight off ones legs if stranded on rope.(self rescue) The use of the dorsal attachment makes self rescue extremely difficult.Dorsal attachment is the worst for suspension of any length.
There were drop tests performed at ITRS (international technical rescue symposium) in 2001 by Rigging for Rescue which showed the danger of using the dorsal attachment. When the mainline is attached to the waist connection and the safety to the dorsal, mainline failure results in a violent change in suspension position. This reaction sends the head flying into the litter or wall which the rescuer is facing. On the other hand, a sternal belay results in a gentle setttling in to the belay system.
All of this data seemed useless as we were still bound by the legislation. However, the area of Canadian legislation which addresses this issue of the dorsal attachment isCSA Z-259.1-M90 . In the scope of this document part 1.3 it states "this standard does not include harnesses for use by firefighters or for use in recreational situations, such as mountaineering ". CSA acknowledges that we follow different standards.(NFPA,UIAA)
Alberta Occupational Health and Safety is also breaking new ground in formally recognizing rescuers in their new fall arrest legislation. Part 10 section 121 states "rescue personnel involved in the training and provision of emergency rescue services are permitted to use equipment and practices other than those specified in this part of the regulation ". Even before this new legislation officially comes into play, OH&S does recognize different applications. Rescuers simply need to submit their system to them for approval. OH&S recently gave approval to an individual performing lift evacuation and rescue to use mountaineering equipment. If you look into it a lot of jurisdictions will allow for a similar approval.Interestingly enough, CSA and OSHA(US) are two of the only standards in the world which dictate the use of the dorsal attachment for fall arrest.
People need to realize that they have been misled for years to believe that dorsal attachment is safer. We have been fortunate enough up to this point that there have not been any serious accidents. For once, however, I would like to see the rescue community be proactive instead of reactive.I am not sure how our brothers in the US will deal with this issue with OSHA as I could not get much info from them(OSHA). If any are reading this, however, I would investigate if I could recieve an approval from OSHA.
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11-27-2002, 01:57 PM #1
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Fall Protection legislation and High angle rescue
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