Re: Trail Run - Elevation change calculation

KMcK wrote:
I would like to know how the elevation change for a given trail run is calculated.

The organized trail runs I have been in through Pacific Coast Trail Runs give an "Elevation Change". This number doesn't seem to be the difference between the highest and lowest point. It certainly is not the total vertical distance up - the total vertical distance down. All these runs start and end at the same point so using this method the elevation change would be zero.

I have already sent an inquiry to PCTR, but I wondered if anyone else would know how this calculation is done.

Not sure how PCTR does theirs, but I usually do it by using barometric altimeter on my hrm. If I were using a gps with barometric altimeter, I'd probably use that. If it's a straight up climb (not rolling up), I may be able to get decent reads (like benchmarks) at trailhead and top, and take that difference. Like you mentioned, some may refer to the difference between highest and lowest elevation. Some combine up + down into "elevation change". Some may add major "ups" on a map, but beware of what's between the contour lines. Some may use gps (actual readout in the gps). Some may use gps route overlaid on map, and the software generates the elevation profile and total climb and total descent. Some map software takes the route, and generates the profile from the elevations in the gps, others take it from its database underlying its map (electronic). But this really depends on accurate gps route and good data on the electronic map. It's useless on rolling trails that I run because of the steep sides.

I've heard the best elevation estimates probably come from gps that have built-in barometric altimeters (used to use one at work). The gps can set the altimeter at the start, and I believe there's some interaction between the altimeter and gps readings to take weather-related changed in pressure into account, iirc. Or at least that was my understanding a couple years ago when I was making some purchase decisions. Technology - both on the receivers and the system - changes.

And I'm sure there's a few more techniques. These are the only ones I've tried though.

Dot

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