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View Full Version : Anyone run Seattle Half this past weekend? Tunnel induced over-mileage?



ULTRACHROME
11-30-2010, 03:16 PM
Just ran the half this past weekend. As expected, I lost my signal after entering the tunnel and reacquired it just as I was exiting. If I remember correctly the mile 4 marker was in the tunnel and I was quite surprised to see the 310XT reporting about 4.3. Mileage total ended up being 13.61.

Just mapped the route using mapmyrun.com (http://www.mapmyrun.com/route/us/wa/seattle/489129115469314384) and it too seems to think the course was a little long measuring 13.39mi.

My two previous halfs (Mercer Island and Missoula) measured between 13.19 and 13.24mi. Eugene Marathon measured 26.39. So I'm used to seeing it measure a few extra tenths over long distances.

Anybody else see this kind of error with a long tunnel?

DATEZZ
11-30-2010, 03:42 PM
When a gps loses signal at one point and then regains it at another point it will connect those 2 points with a straight line. If the tunnel was relatively straight and you did not make any major turns before signal was regained then the mileage would be correct. There would be no error from going thru the tunnel.

ULTRACHROME
11-30-2010, 04:12 PM
When a gps loses signal at one point and then regains it at another point it will connect those 2 points with a straight line. If the tunnel was relatively straight and you did not make any major turns before signal was regained then the mileage would be correct. There would be no error from going thru the tunnel.

The results on connect.garmin.com (http://connect.garmin.com/activity/58437788?sms_ss=email&at_xt=4cf583efeec8864c,0) agree with what you're saying. The tunnel is pretty straight.

Given that I noticed the extra mileage in the tunnel when I had no signal, it seems the error would have occurred prior to the tunnel.

CARRINGTONCYR
01-18-2011, 07:07 PM
When running Marathons or Half Marathons always keep in mind that the course is measured based on the shortest possible route that a runner could possibly take on any given course. Its not at all unusual to run "extra" distance especially when you're running in a crowd of other runners. Its not always possible to run the "ideal" route.

That fact combined with poor satelite reception while running down 5th Avenue in downtown Seattle, as well as heavy tree growth through the Arboritum section of the half Marathon is what gave you your extra distance. Over the course of "13.1" miles, given the terrain that you ran through, I'd say an extra .3 miles for GPS error plus .2 miles actual extra distance run is not out of the question.