“The Half Dome Cables Study” Part 2

Half  Dome – Yosemite Musing
     So from yesterday, in addition to the electronic TRAFx counters set up, the research team also did a manual count. These counts were done from 5:00 AM to 7:00 PM at the Happy Isles trailhead and from 9:00 AM to 4:00 PM on the Half Dome Trail at its junction with the John Muir Trail (aka the split). This is way up the switchbacks after Little Yosemite Valley.  Information recorded with the calibration counts includes: 1) time of day for each passing visitor; and 2) direction of travel of each passing visitor (i.e., arriving or departing the corresponding trail). This data were used to calibrate the TRAFx devices and as input to a computer simulation model of visitor use of the Half Dome Trail and cables route. What they were able to do was to gather accurate data on the actual flow of people every day – they could plot the number of people going up/down from Happy Isles and up/down from the HD-JMT trail split. For example, on a Saturday at noon over 90% of hikers are going up as they pass Happy Isles and the flow doesn’t move into a down flow until 1 pm when most are now heading home.
     Before you say “Duh,” They also ASKED people at Happy Isles where they were going – Half Dome or other destinations.  This one surprised me. On a given Saturday, 567 responded that they were intending to go up the cables; 2131 said they were going elsewhere. Could be Glacier Point, Merced Valley, Cloud’s Rest or just Vernal or Nevada Fall.  Of those, 97% were heading to Half Dome between 5  and 6 am. With only 3% heading to the cables by 10 am. This shows that most folks have the message to LEAVE EARLY. Now since no report is any good without graphs, I present the actual report graph of the Half Dome route. It’s probably too small to read – the vertical is the # of arrivals at the HD – JMT split and the horizontal is time.

The upper line is people heading towards Half Dome at the trail split. Below that is those ONLY going to the cables (others go on elsewhere and are called Outliers). The third line from the top is the mean number Sunday – Friday that are at the split with the bottom one (almost overlapping) is  the Sun-Fri count going to the cables. The observation is that it reflects a 3 am blip as people go up to watch sunrise but the bulk are at the trail split before 10 -11 am.  If you get there by 11 am you are s-l-o-w and will most certainly will face a crowd at the cables.  Anyone still with me? While all this is pretty dry, it does show a scientific methodology that will lend credence to the study. Tomorrow we plow on and look at just how many people actually get to the cables and how many poop out before – as well as a discussion of why/how many people go outside the cables. One you should not miss.
Unrelated thought worth quoting: “I am only a piece of jagged human mist drifting about these rocks and waters Heaven only knows how or wherefore.” – John Muir, 1872
*Mr. Half Dome – Rick Deutsch – www.HikeHalfDome.com


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