[Volunteers_fosm] Hiking CATIP System

[Joseph C. Giles]

Having published the CATIP webpage <https://friendsofthesandias.org/projects/projects-trail-building/cienega-armijo-trails-improvement-project-catip/>, I thought I should get more familiar with the trails myself having hiked only Cienega, (parts of) Acequia, Armijo, and Faulty previously. This morning I did a hike of about 7 miles (more discussion later) using a route that included all our parts of 9 trails. 

I encountered no down trees or other obstacles on the thoroughly enjoyable hike.



The weather was perfect. I was very impressed by the trails, the signage installed on them, and the beautiful forest they traverse. Given the clear signage at every intersection and maps placed at many of them by Don Carnicom, I thought it impossible for anyone to get lost; however, a couple of women hikers said they managed to do so briefly. BTW, the 8 women hikers I encountered in 5 groups outnumbered the men 4:1.

The out-of-date maps available on my trusty Garmin GPSMAP 64S do not include any of the new trails. Conversely, Gaia on my iPhone has all of them, so I used both devices to record my track (and keep from getting lost). Other GPS aficionados may be interested in a comparison of the results. 



As you can see, the tracks overlay almost perfectly after importing the Gaia GPX file into my Garmin mapping software. However, as you also can see, the reported distances and elevation gains differ substantially. (Gaia* in the table above refers to the results reported by the Garmin software using the Gaia GPX data.) 

I have my Garmin device set to Auto for tracking. The Garmin manual states: “Auto records the tracks at a variable rate to create an optimum representation of your tracks.” This resulted in 675 data points after I deleted 3 or so recorded while I was loading stuff into my vehicle at the end of the hike. I’ve learned by experience that deleting even a single data point always results in a reduction in reported distance traveled, sometimes by 5% or more, because doing so causes the software to execute some sort of filtering of the data.

The iPhone GPS appears to record once every second. The Gaia GPX file included 1146 points⏤almost twice as many as the Garmin device⏤after I deleted a similar number of points from the end of the file. Strangely, deleting these points did not result in a reduction in reported distance traveled.

I have no explanation for why the reported distances and elevation gains differ so much. I guess the message is that these GPS readings are estimates and not absolutely accurate values.

I encourage everyone to enjoy these wonderful trails.

Cliff Giles


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