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121st HM – Course Measurement / Garmin accuracy test

My 121st HM was run today under rather difficult climatic conditions. But in the summer months when there are no events to run, I like to do something interesting with the runs to keep me engaged.

This is what I did.

Picking up on our newly acquired skills in Course Measurement, on Friday I got Vivek Soni, Dipesh Gindra and Himanshu Vinchhi to join me on the Eastern Express Highway at the usual spot where Highway Runners schedule their usual monthly supported runs.

Armed with the tools that we needed to get the job done, we measured a 450 meters course using a steep tape and marked the calibration course in 50 meters segments. We drove nails on the road and used paint to mark them.

We then did the constant readings on the Jones Counter and after arriving at the days working constant, we measured 5 km in 1 km segments. At each Km mark, we drove nails and painted them.

We thus ended up with a 5K measured route.

Today, I reached the spot at 5.10 am and started my run at 5:30 am. It was my intention to get as much of the cool weather as possible. I ran to the 5K mark and it was still dark. I missed the nail on the group and overshot the distance by about 200 meters. I had the pleasure of meeting Shyam Tallamraju on the route. I also had met him earlier this week at TCS expo, two times in one week with an accomplished runner.

On my return leg, the others of Highway Runners had also started and the water station support was up and available.

I wore two Garmins on my hand. This time I did something that was not done in my earlier studies. I wore my Vivosmart and 920XT on the same wrist to prevent any misapprehension that my one arm separates itself and travels further than my other hand :-)

My purpose of choosing EEH for this study was two-fold

I wanted a straight as an arrow route so as to prevent any issues with not having taken the SPR ( Shortest Possible Route ) especially when curves are involved.

I wanted an open to sky space so that multipath deflection from tall buildings does not skew the GPS signals

The results are as under:
My Vivosmart recorded a distance of 23.23 Kms:

My 920XT recorded a distance of 22.72 Kms:

I know that I ran a measured course of 21.50 Kms at the most after accounting for the overshooting of the turnaround point.

So there, for those who live and swear and run and organise running events using GPS technology., yet another study to prove that the distances can vary a lot.

I had the privilege of meeting Breeze Sharma after his return from the Mt Everest expedition.

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