Two Tensioned Rope Rescue Systems
For decades, rescue agencies and teams have configured their rope rescue systems around some variation of a fully tensioned main line and an untensioned safety or belay line. Organizations and manufacturers have invested a great deal into research and training to make these rope rescue systems as safe as possible. Tensioned main-untensioned belay rope rescue systems have performed well through many thousands of rescues and training evolutions primarily because main lines rarely fail catastrophically, which is where we encounter the drawback of main- belay rescue systems.
Peak Rescue Institute (PRI) teaches the TTRRS in the technician class utilizing two CMC MPDs. In the Specialist class we teach the TTRRS based both on MPDs and on Super Munter hitches. Of all the devices we have tested with the TTRRS only the MPD and the Super Munter are able to control the sudden transfer of forces that occurs in the event of one rope (or operator) failing.
One of the concerns regarding the TTRRS versus a main-belay system has been the potential for rope damage when transitioning a sharp edge. Since it is easier to cut a rope under tension, some believed that a TTRRS was more likely to suffer rope damage on a sharp edge since both lines are under tension during the operation.
Using both ropes to control the load eliminates the drawbacks found in main- belay systems. Because the load is already borne by both lines, both ropes have already been partially pre-stretched, and because the load on each line is already controlled by a fully competent device such as a Super Munter or a CMC MPD, some of the technique issues encountered in reduced unweighted belay operations are also addressed. If one line fails in a TTRRS, the forces transferred to the other line and the peak force transmitted to the people on the end of the rope are substantially reduced.
Obviously there is a lot going on and I want to cover this thoroughly… so when this project releases this summer we can dedicate more time and conversation. In the meantime, I want to put in a shameful plug in for one the best and hands down superior courses in all the land. Not only are you treated like kings and queens, but because of the student:instructor ratio often being 4:1… the close attention to each student is out of this world. Oh… the food is off the charts too (Ya!!! you are fed like royalty).
Peace on your days!!!
Founder and Visioneer
Rigging Lab Academy