Measuring Track portion of a 5km Course

I would have no problem certifying a 5k with the track measured as described. Granted, a vinyl tape may be somewhat less accurate than a steel tape, but the error is small, and is only a fraction of the overall distance.

I would not certify a calibration course laid out using a vinyl tape.

I hope they let you ride the bike. Taping around the bends without a curb in place is likely to be a major pain.

Pete/Ken, Would an alternate approach if not allowed to ride on the track be to walk the bike around the track? The constant would be a little smaller, but as noted, the error and the portion of the course so measured are also small. I suppose you could determine a walking constant.
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Why not measure the distance from the 5k finish to the track finish line? Then you would know the distance to the 300-meter start line of the track. You would then have to measure only a small portion of one turn.

Or why not use a calibrated measuring wheel? Just about anything would be easier, and probably more accurate, than taping around a curve.

Like Pete, I would not have a problem with the use of the vinyl tape for your purpose. Vinyl tape tends to stretch, so your measured distance will likely display a smaller value than a steel tape.

You may be able to save some time by using the track markings. The track is appears to be a standard 400 meter length (check with the HS track coach) and your path is mostly along the inside of lane one. You can take measurements in three sections and use some math to get your distance on the track. If you join lane one in the center of the arc and finish at the 50yd line, then the distance on the track in lane is approximate. 300 meters.

Hope this helps. -- Justin

PS. To measure around a bend, you could use cones. Position the cones on the track and run the measuring tape along the side of the cones. jk

I measured a course that started and finished at the 200m mark of a track, with the runners starting going clockwise (opposite direction of normal track race) to the 100m start line, then finishing coming in and running from the 100m to the 200m mark in the normal (counterclockwise) direction.

While I had full access to the track, I felt the track surveyor's measurements were probably more accurate than any ride I could perform, so measured from the 100m start out onto the road portion of the course and back, and just added 400m to that distance.

If we can't assume a track is the correct distance, the whole sport is in trouble.
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If we can safely assume that tracks are correct, are we wasting our time certifying them?

Pete, I don't think we do certify tracks very often. Most of them have a certificate of accuracy from the builder/surveyor. I've witnessed a measurement of one or two while they were being built and the equipment used far exceeds a calibrated bike, or even a steel tape around a curve, for accuracy and precision.

I've certified a handful of tracks, and I have never found a track owner who possesses a certificate of accuracy from the track builder. The track used in the Atlanta Olympics was the sole exception.

I think this might be one case where you could measure a course just as accurately with Google Earth as you could with a bicycle. The inside edge of the track is probably visible in the satellite imagery. I bet you could be within a meter, and probably lot closer, with a GE measurement.
On a bike you have the issue of spending half your ride trying to maintain a constant offset from the inside edge of a turn. Plus, you have calibrated on a surface that is very different from the one you are measuring on.

I just tried this on a 400 meter track which I measured earlier this year with a calibrated measuring wheel.

Using Google Earth I got 399.42 meters. I used the length-width method, and the length at the inner line was 397.54 m. I added 1.85 m to account for the 30 cm offset.

Things got a tad blurry when trying to find the outer edge of the inner line.

Close but no cigar.

My measuring wheel measurement of the track may be seen by downloading OH10005PR from the USATF course search web site. All calculations are on the map. The track was measured because they had lost their original surveyor's certificate and had somebody who wanted to go for a Guinness record of 11 marathons in 11 days.

Boy, the lines on that track from OH10005PR are hard to see. I measured one of my local tracks instead. Followed the inside edge of lane 1 all the way around and got 399.42m. Then did the 0.3m offset calculation to get 401.30m.

So I decided maybe lane 1 is a little hard to follow since it is next to the grass. I followed lane 2 all the way around and after the (lane width - 0.3) offset calculation I got 401.56m, assuming a 42" lane width.

To be 1.5 meters long I would need to have added over a fifth of a lane width to the measurement. Something's fishy, either GE or the track.

Here's a link to my measurement of lane 2.
http://tinyurl.com/37cssha

Google Maps shows a bad approximation of the path. You'll have to view it in google earth to see the real path I measured.

Tried a different track near me. The measurement with Google Earth came out to 399.06m by measuring lane 2 and then adjusting for the offset. Below shows the measured path, but again you have to open in google earth (not google maps) to see the real path.

http://tinyurl.com/25v9x37

I'm definitely going to have to head out to both these tracks with my steel tape and measuring wheel.

Went to the track this morning to take a measurement. Steel taped from the 100m mark to the finish, calibrated my wheel using that cal course, measured the inside line of lanes 2 and 5 all the way around, and then adjusted the measurements based on the measured lane widths.

Final results
length of track based on lane 2 measurement: 399.833m
length of track based on lane 5 measurement: 399.947m
length of track based on Google Earth measurement: 401.56m.

So Google Earth was off by about 0.37%. It should be noted that this is an error caused purely by the imprecision of GE's imagery and scaling, not by any inability to follow the true path(which of course is another source of error for Google Earth measurements).

Thanks all for your responses to my original question. I did get permission to ride my bike on the track and completed the measurement without any difficulties.

In riding my bike from "Finish" on track at 50 yrd line , riding 300+ meters on the track and out to the road, the distance based on counts was 365 meters. Measurement using Goggle Earth was 363 meters.

Most track markings are much more accurate than anything we could do.
There have over 200 measured marks that you can use (400m hurdles, relay zones, start lines, etc.) all of these are standard distances and available online.
Only the IAAF Certifies tracks for accuracy.
Also as a reminder tracks with curbs are measured 30 cm from the curb in lane 1. All other lanes are measured 20 cm from the outer edge of the white line of the lane to the left.
Tracks without a curb are measured 20cm from the outer edge of the white line to the left in all lanes including where a curb would go.

That brings up an interesting point David. How are most tracks laid out? Are they laid out assuming there will be a curb (.3m from the outside edge of lane 1 is 400m) or assuming there will not be a curb (.2m from the outside edge of lane 1 is 400m).

For my middle school track that I measured above, the two measurements of the loop .3m from the outside edge of lane 1 came out to 399.83m and 399.94m. The loop .2m from the outside edge of lane 1 would be 399.20m and 399.32m. There is no curb on the track.

Are all tracks laid out with the .3m offset even if no curb is installed?

Mark
You have identified one of the great problems with track measurements.
There are many, many (too many) high school tracks that are measured incorrectly in the US. This is how it works sometimes: A school district wants to build a new track. They hire different subcontractors to build the foundation, the irrigation, the rubber, surveyor, and stripper (line painter).
The surveyor is usually state licensed with no clue about the measurement rules (curb vs. no curb. Because of the expense and logisitcs, most high school tracks are built without a curb but the surveyor measurers it as though it would have one!

I believe that many modern tracks are constructed with temporary curbs. Sockets are set on the inner line, and when track meets are held, a big pile of aluminum segments are plugged into the sockets and voila! a curb!

This makes football more safe, as off-field tumbles by players do not land the athletes on a curb.

If you see sockets, it can be presumed that the track was laid out with a 30 cm offset. As David says, whether this was actually done is open to question.

David is dead right about potential problems. I've measured several tracks and have yet to find an owner who can produce a certificate of accuracy generated by the original track measurer.

Our method of verifying the accuracy of a track is pitiful compared to what should be done by the people who construct and measure the track.

Last time I looked at the IAAF site, I recall that a full-dress verification of accuracy for a top-of-the-line track costs in the neighborhood of $25000.

The IAAF charges $10,000 for a Class 1 Certification and $1,000 for a class 2. This does not include the amount that facility owners would need to pay the surveyor.
http://www.iaaf.org/mm/Documen..._CertSys10_18102.pdf