Course Distance Accuracy!?!?

rassha01

Although most here probably don't consider a 5k "long distance" I thought the premise of my post would also fit longer distances.

Has anyone signed up for a race with a goal in mind and come to find out that the race was not the actual distance as advertised? I ran a 5k over the weekend that I signed up for some time ago to try and break the 21 minute mark. I did PB it but my time was 21:17, only a 2 second gain from my previous. I was a little disappointed in myself after putting in all the work just to get a lousy 2 seconds. Well come to find out the course was actually 3.3 miles and now I feel a little cheated!! Anyone else have a similar experience or am I just being 2 anal?

It was for a good cause though :happy:

davemunger

Nothing more frustrating than an inaccurate course. Ideally a course should be a little long, but not much. A 3.1-mile 5K should be about 3.11 miles, just to make sure it's not short! If there's anything worse than a long course it's a short one. Imagine if you had hit your goal only to learn the course was 3.0 miles. Then you'd never know if you could have made it.

At least with a long course if you PR you know it is legit.

That said, Garmins are not perfectly accurate, and runners don't necessarily run the course perfectly, so it is entirely possible that someone's Garmin got the length wrong and your course was correct. You can search the USATF website to see if it is certified, but the site is a little difficult to use:

http://www.usatf.org/events/courses/search/

_Josee_

Someone told me once about course beeing mesured weirdly: like a curve would be taken on the "inside" (shortest part)... So if you are running it on the other side, you'll be running a longer distance. Also, add some zigzaging you might need to do to get pass some other runners and that kind of thing...

That may add up quite a bit... Just a thought.

KeithAngilly

If the course was certified by USATF, then this may help:

http://www.usatf.org/Products-/-Services/Course-Certifications/USATF-Certified-Courses/Procedures-Manual/The-Shortest-Possible-Route.aspx

GPS is definitely not accurate enough to determine is a course is measured properly, unless the course is really way, way off.

ATT949

Although most here probably don't consider a 5k "long distance" I thought the premise of my post would also fit longer distances.

Has anyone signed up for a race with a goal in mind and come to find out that the race was not the actual distance as advertised? I ran a 5k over the weekend that I signed up for some time ago to try and break the 21 minute mark. I did PB it but my time was 21:17, only a 2 second gain from my previous. I was a little disappointed in myself after putting in all the work just to get a lousy 2 seconds. Well come to find out the course was actually 3.3 miles and now I feel a little cheated!! Anyone else have a similar experience or am I just being 2 anal?

It was for a good cause though :happy:

"the course was actually 3.3 miles" - how do you know that it was 3.3 miles?

arc918

A must read for those who think their Garmin or iPhone is the last word on distance!

http://www.clevelandmarathon.com/resources/userUploads/CertifiedCoursevsGPSAccuracy.SRV_1338321859.pdf

rassha01

Although most here probably don't consider a 5k "long distance" I thought the premise of my post would also fit longer distances.

Has anyone signed up for a race with a goal in mind and come to find out that the race was not the actual distance as advertised? I ran a 5k over the weekend that I signed up for some time ago to try and break the 21 minute mark. I did PB it but my time was 21:17, only a 2 second gain from my previous. I was a little disappointed in myself after putting in all the work just to get a lousy 2 seconds. Well come to find out the course was actually 3.3 miles and now I feel a little cheated!! Anyone else have a similar experience or am I just being 2 anal?

It was for a good cause though :happy:

When I checked my GPS when I got home it said I had run 3.3
"the course was actually 3.3 miles" - how do you know that it was 3.3 miles?

I checked my record on Endomondo when I got home and it said I had run 3.3. In disbelief I mapped it out on google earth as I have done with many other courses I have ran and it was actually a bit longer. I checked with another local that ran it and his Garmin said 3.27. I realize that all of these can be off but they are usually fairly accurate for other races, 0.2 miles seems quite a bit to be off for a 5k. Also, it was not a certified course as it was a small fundraiser for a local yellow ribbon society so I doubt they took a lot of care in measuring.

rassha01

A must read for those who think their Garmin or iPhone is the last word on distance!

http://www.clevelandmarathon.com/resources/userUploads/CertifiedCoursevsGPSAccuracy.SRV_1338321859.pdf

Looked forward to the article but it seems to have been removed. = (

arc918

Google up: "In GPS we trust"

rassha01

Did some searching/reading after I tried the previous link = ) Just seems odd that at most other races it was fairly accurate and this one was glaringly off. Oh well just seeing if anyone else had similar experiences.

SonicDeathMonkey80

This happened to me at a HM in June. My phone's GPS said I did it in 1:35 and I nearly pissed myself. How it got to be 9 minutes off is beyond me, but I don't trust the distance measurement anymore. Instead I use my Garmin as a training tool to analyze splits, HR, pace, and terrain.

davemunger

I checked my record on Endomondo when I got home and it said I had run 3.3. In disbelief I mapped it out on google earth as I have done with many other courses I have ran and it was actually a bit longer. I checked with another local that ran it and his Garmin said 3.27. I realize that all of these can be off but they are usually fairly accurate for other races, 0.2 miles seems quite a bit to be off for a 5k. Also, it was not a certified course as it was a small fundraiser for a local yellow ribbon society so I doubt they took a lot of care in measuring.

GPS is usually not off by that much; sounds like the course was a little long. Yes, GPS is not as accurate as wheeling the course but when several runners' GPSs agree, that suggests the course is not right. I give race directors the benefit of the doubt if my GPS is within 0.1 mile but anything over that, especially if several GPSs agree, is probably due to a faulty course layout.

arc918

GPS accuracy can be really be sucky if the course has tall building around or tree coverage.

That being said, a perfectly accurate course can be all messed up if somebody puts a cone in the wrong place or something.

davemunger

GPS accuracy can be really be sucky if the course has tall building around or tree coverage.

That being said, a perfectly accurate course can be all messed up if somebody puts a cone in the wrong place or something.

True, but if multiple GPSs are in agreement, and also agrees with a mapmyrun or similar plotting of the course, then to me that suggests that the race director screwed something up.

arc918

GPS accuracy can be really be sucky if the course has tall building around or tree coverage.

That being said, a perfectly accurate course can be all messed up if somebody puts a cone in the wrong place or something.

True, but if multiple GPSs are in agreement, and also agrees with a mapmyrun or similar plotting of the course, then to me that suggests that the race director screwed something up.

I agree, it's just all the "my GPS read 26.32, Chicago was long" posts that drive me nuts.

davemunger

I agree, it's just all the "my GPS read 26.32, Chicago was long" posts that drive me nuts.

AMEN!

bert16

I ran a 5K in August that was most definitely short, which was super frustrating. Sort of impossible to PR if you don't actually run 3.1 miles! And the ridiculous thing was that the course was a simple straight out and back; how can the race organizer not correctly figure out where the turnaround point should be?!?!? It was 2.92 mi by my Garmin; I asked three other people with Garmins on and they were within 0.02 mi of my Garmin. The time was another indicator; the pace was just much faster than what I was running at the time. Similarly, I ran a (completely disastrously organized on so many levels) 15K (9.3 mi) a couple years ago that was way short... my Garmin clocked it at 9.11 mi.

I'm an aerospace engineer, so have no delusions about the accuracy of GPS, but given the overall time (and implied pace) and others complaining of the same issue with their devices, those errors were too great to chalk up to GPS. For my 5K turkey trot last Thursday, my Garmin clocked 3.17 mi, but I'm assuming that's a combo of my weaving through people near the start, running the wider part of the course at times, and GPS error in the city. And no worries, since I PR'ed, anyway!

Soooo... yes, it happens, and it sucks when it does; you just stand a better chance on a certified course. Happy running! :flowerforyou:

ATT949

Although most here probably don't consider a 5k "long distance" I thought the premise of my post would also fit longer distances.

Has anyone signed up for a race with a goal in mind and come to find out that the race was not the actual distance as advertised? I ran a 5k over the weekend that I signed up for some time ago to try and break the 21 minute mark. I did PB it but my time was 21:17, only a 2 second gain from my previous. I was a little disappointed in myself after putting in all the work just to get a lousy 2 seconds. Well come to find out the course was actually 3.3 miles and now I feel a little cheated!! Anyone else have a similar experience or am I just being 2 anal?

It was for a good cause though :happy:

When I checked my GPS when I got home it said I had run 3.3
"the course was actually 3.3 miles" - how do you know that it was 3.3 miles?

I checked my record on Endomondo when I got home and it said I had run 3.3. In disbelief I mapped it out on google earth as I have done with many other courses I have ran and it was actually a bit longer. I checked with another local that ran it and his Garmin said 3.27. I realize that all of these can be off but they are usually fairly accurate for other races, 0.2 miles seems quite a bit to be off for a 5k. Also, it was not a certified course as it was a small fundraiser for a local yellow ribbon society so I doubt they took a lot of care in measuring.

Per other posters, rainmaker has a good article on this.

When a course gets USTFA certified, they cover the course with a measuring wheel and, since the road course is empty, they can hit all of the tangents.

In contrast, when relying on a GPS, not only do you have the inaccuracy of the GPS (I've got well over 100k miles on half a dozen GPS receivers and the best I've seen is 7' precision) but you've got to run around other runners as well has hit try to hit the tangents.

Or, like I did in February, there's always the "brilliant" move of forgetting to hit the stop button after the race!

rassha01

Thanks for all the responses!! Think I will set my goals for bigger events and run the smaller ones just for fun. :laugh:

DavidMartinez2

If there's anything worse than a long course it's a short one. Imagine if you had hit your goal only to learn the course was 3.0 miles. Then you'd never know if you could have made it.

This happened to me at my Turkey trot 10K last week. Fortunately I was warned it might be "a little" short so I checked my Garmin at the finish line: 5.9 miles. I kept running until it read 6.21

SonicDeathMonkey80

If there's anything worse than a long course it's a short one. Imagine if you had hit your goal only to learn the course was 3.0 miles. Then you'd never know if you could have made it.

This happened to me at my Turkey trot 10K last week. Fortunately I was warned it might be "a little" short so I checked my Garmin at the finish line: 5.9 miles. I kept running until it read 6.21

Same at my halloween 10K - it was four laps around a 1.5mi jogging trail. When I asked about the distance, the race director said nobody would care about the 0.2mi difference, so I just kept going til 6.21 like you did. Military folks putting on events can be pretty lazy - all he had to do was start us and then move his crap down a little ways.