This group wants a third cable added to Half Dome. What happens if it is still overcrowded? A fourth cable? You might as well do what the first ascender George Anderson wanted and chisel a set of steps into the granite. We did Half Dome before the permit system on the day after Labor Day. That late in the season, the cables had a reasonable number of people on them. Even so, I would not do Half Dome again unless I wore a climbing harness and clipped into the cables. Otherwise, if someone above you falls, you could get knocked off, too.
