DAMAGE FROM STEPPING ON YOUR ROPE
Several years ago the German Alpine Club investigated the damage to ropes caused by stepping on them with boots. They concluded that a rope could not be noticably damaged by such action. However, they did not do away with German tradition - the guilty party still has to pay for a beer. Similar tests were performed using crampons.
A 90° angel iron was used as the edge and a multifall rope (minimum number of nine falls) draped over the edge. A person weighing 80 kg stepped on the rope and rolled three time back and forth with full body weight. This process was repeated 13 times at a spacing of 1.5 cm. The rope then underwent the UIAA drop test. The damaged area was placed at the orifice, the carabiner edge of the test apparatus. In another test the damaged area was placed in the free length of the rope. In both instances the number of falls held was still nine.
While one cannot say that stepping on the rope did not cause damage, one can say that it is negligible.
This test was more difficult to execute. An 80 kg person stepped on the rope with new crampons, which rested on a stone surface and twisted the foot. While the rope cross section deformed, the crampon point was not able to penetrate the rope. In order to be more certain, the crampon point was hammered into the rope until the point could be felt on the other side. The mantle fibes were then removed with a hard pointy tool until the tip of the crampon was visible (see figure). This was again done 13 times at a spacing of 1.5 cm. The test results were the same as above - the rope still held nine falls.
With regular crampon use and no obious damage to the mantle, there is no need to retire a rope, if a climber steps on it with a crampon. Keep in mind that these tests are done on a rock base. Stepping on a rope in snow can well be ignored. In almost every instance, the rope rolls sideways and because of the soft base, there cannot be any penetration.
Some ice climbers sharpen the points of their crampons like a knife, much sharper than when they are purchased. The test was repeated with such a crampon point, which not only had a very sharp point but also sharp edges like a knife. This point penetrated the rope with the same ease as a pointed, sharp knife. The result: the rope held only four falls. While this is of some concern, a rope is still unlikely to be cut over a rock edge after such damage occurs. Furthermore, the damaged area has to be over such an edge, an unlikely event. Again it is questionable whether this damage could be reproduced when stepping on the rope in snow.
The conclusion is that damage to a rope by stepping on it has been clearly exaggerated, even with crampons.