Measuing A 400 meter track, revisited...

You shouldn't add in a 0.001 for a properly measured track. My understanding is that they are made with a SCPF designed in. I recall that when Roger Bannister broke the 4-minute mile in May 1954, surveyors measured it at 0.5 inches oversize so Bannister ran an extra 2 inches.

Jeff,

The definitive tome on all of this seems to be the IAAF Facilities Manual. It's a huge document, comes in 2 volumes. Here is a link which, I hope, gets you close to the questions you are asking:

Track measurement specs

If the link just gives the whole book, then look on around page 34-36. Apparently there is a "28 point measurement" you are supposed to use. (Not you, or me, but a surveyor!) But they are talking about IAAF certification, and for all the marks on the track, and that's not what we are doing. Anyway when all that is completed, the computed distance is to be not less than 400.000 meters, and not more than 400.04 meters. So one part in 10,000 over is ok and it may not be less.

I really don't know how we should handle any SCPF. I didn't apply a SCPF. Mike Sandford recently wrote about measuring a track and he did apply one, based on information about tape accuracy etc.

I found the track length I did recently to be 399.9 meters. Ouch, that's awkward! Perhaps a survey with good instruments and methods would find that it is 400 meters after all, but I just reported what I found, and race directors can do with that what they will.

One more thing: the IAAF manual states that if you're using a steel tape to measure distances, you are supposed to measure the tape's temperature before and after each measurement using a "contact thermometer." I don't know what that is or how hard it would be to find one. I only hope that my run-of-the-mill thermometers, that I lay down near where I am measuring, get me at least close to a correct value.

Track measurements have been a raging pain for as long as I can remember. Because they are initially laid out with a very small SCPF, any measurements of which we are capable are as likely to show shortness as longness. We simply can't split the hairs that fine.

If our taping per the "Taping a Track" instructions comes up with a measurement very close to the desired 400.00 m, I'd suggest that we consider the track length as certified per our check. How close? I'd say if we get anything between 400.04 and 300.96 m, that would be good enough to confirm that the track layout was initially OK. Call it "400m" and note the actual length obtained somewhere on the certificate.

I'd suggest that certifiers take an even strain and certify the track using this criterion. It should serve the need of any non-track-meet event likely to be using the track.

I don't expect this to come to pass, but it makes sense to me.

I agree with Pete. If we measure a track by using the "taping a track" method (steel taping from center of curve to center of curve, and two width measurements) and come up with a distance that is very close to 400m, then we should just assume that the track was laid out correctly and is 400m.

But the question is, what to do if this measurement technique comes up with 396m? Are we going to certify it at 396m? I don't think we should do that without taking an actual measurement of the track distance, either by measuring around the track with a steel tape or with a calibrated measuring wheel.

A big assumption of the "taping a track" technique is that the turns are semi-circles. If we discover that a track is not laid out correctly to 400m, I think all assumptions about how it was laid out must be tossed, and it should be measured directly.

My preference would be to not certify any track that does not check out to its nominal length.

You can't always get what you want.

We lack the expertise and resources to measure tracks to a standard like IAAF's.

Running events on a track can produce two kinds of american records: track records and long distance running (LDR) records. For american track records, the application includes a track certificate from a licensed surveyor. Here's an example of a track certificate for the Boston University indoor track. (Click the image to see the complete certificate.)



The BU track certificate includes the data to show the location of the finish lines, break lines, starting lines for the 200, 400, 500, 800, 1000, mile, 4x400 relay, 4x800 relay on the oval and well as the hurdle locations for the straight inside the oval.

The track certificate is sometimes misplaced but should be available from the track's athletic department, the original track designer or from the company that striped the track.

American LDR records may be set on tracks that have been certified using the RRTC measurement techniques. If the track measurements were made entirely with a steel tape, and a bicycle was not used, then I would not include the Short Course Prevention Factor in the calculations. (The SCPF would be used to correct for wheel wobble associated with a bicycle measurement.)

NOTE: tracks have different shapes. An IAAF track has two straights of 84.39 meters and two curves with a radius of 36.80 meters. The equal quadrant tracks have two 100 meter straights and two 100 meter curved sections. Newer tracks are designed to fit a full soccer or lacrosse field. Some tracks, known as broken back curves, may have multiple radii for the curves.

Hope this helps. --- Justin

Readers interested in seeing how some RRTC measurements of tracks came out should access the archive of past issues of Measurement News. Search the index for "track."

In Issue #57, January 1993, they will find the following text. If you actually search for and read MN#57 you will find page 24, which contains a bit of discussion.

Very interesting topic. It seems for a track record to be upheld I feel it must have a certificate like the one Justin has shown. However, this is not the case now. Maybe a good topic at this years convention.

I do agree with Pete, that we really should get out of the business of certifying tracks.

It would be interesting to know if there is a "findable" center point for the semicircular parts of a track. Of course the IAAF manual specifies exactly how these points are to be marked (certain diameter pipe, buried, etc) but I doubt if that's followed universally. Those points would offer an easy way to check the turn radius at a number of points, and resolve whether the track uses a single radius or something else.

For a rough check, look at the track on Google Earth. For that matter, measure it!

Later - I gave it a try. The track is located at:

40deg 01' 5.43"N
83deg 03' 14.1"W

I came pretty close to 400 m. Don't forget the 20 cm offset from the inner painted line

What did you get?

Never mind - I got 400.01 m. I used an interval or 3 to 4 meters on the curves, and shot the straightaways in one full length. I put the cursor directly on the inner line as best I could. I am amazed at the coincidence. I expect dumb luck had something to do with it.

I also rotated the image to fill my screen and enlarged it to better see the inner line.

I see no particular use for what I learned except that I reinforced my faith in Google Earth.

quote:

Originally posted by Bob Thurston:
It would be interesting to know if there is a "findable" center point for the semicircular parts of a track.

Bob, Take a look at Dr. Wayne Armburst's manual titled "Track Marking Using the Computomarx System."

http://www.computomarx.com/Manual.htm

Look for the section titled LOCATING THE CENTERS OF CURVES.

Hope this helps. -- Justin

FINDING THE CENTERS OF THE ARCS AT THE ENDS OF THE TRACK

1. Assume that the end arcs are circular.

2. Measure the distance between the parallel straightaways. Always measure to the track side of the inner line.

3. Half of the distance obtained in step 2 will be the radius of the arc.

4. Go to the midway point of the end arc and lay out the arc radius length along the central axis of the track. The center of the track field will lie halfway between the two straightaways.

5. Locate the arc center using the lengths previously.

6. Using the arc center as a fixed point, measure to several points along the inner curved line of the track. All of these measured lengths should be the same – if the arcs are circular.

You may have to fiddle a bit, but the above should get you there.

We have measured several road races that started or ended on tracks. We do it using calibrated bikes. We sit on the seat and push the bike with our feet, keeping our weight on the bike and the front wheel on the innermost white line. I realize we are not certifying a track, but a race course. If asked to obtain certification of a track, I wouldn't. If asked to measure a track for information, I'd use Pete's tape method and check it with our bike method. I wouldn't use an SCPF if I could keep the front wheel on the innermost white line.

A few more practical points:

Many high school fields are now covered with artificial turf. It makes locating a precise point a little tricky. I've used pieces of foamcore board, maybe 10" square or larger, fastened to the field by 4 nails. Like 12d or larger. you can mark a point on the foamcore with a ballpoint pen. It's pretty stable.

Fields often have teams or groups practicing on them. Usually a little diplomacy seems to work; at least they can adjust when they do which activity to accommodate what you're doing.

You'll often find that there is a more or less permanently installed high jump landing right where you'd like to measure for the long dimension of the track. Not sure what is the best way to handle this. I constructed a straight line tangent to the inner edge of the inner line, checked to be sure the line was perpendicular to the long dimension (by equal triangles on both sides comparing offset from inner line). Then I could measure from that line to a concrete border just outside the end of the end zone. Do-able but plenty of room for error. Mike Sandford recently wrote about this high jump area problem also.

Once Bob Baumel and I checked a track in Washington DC after an article appeared about how it was laid down incorrectly but then fixed. I remember that we did find those center points and made a bunch of checks for consistency of the radius. I think we used the method Pete describes, but maybe Bob can correct me. (By the way we did find that the track, as we found it, was indeed corrected to 400 meters.)

Justin's information is helpful, thanks for that.

Are surveyors certificates based on rail on (30 cm in from stripe) or rail off (20 cm in from stripe)?

The "measure line" lies 20 cm from the outer edge of the inner painted line on an uncurbed track and 30 cm from the outer edge of the curb on a curbed track.

The surveyor's certificate refers to the length of the measure line.

Thanks everyone for great discussion on this issue. It is real helpful.

Currently, we are still perusing the original engineers certificate. I got a lead via Google by finding a news article on the funding for the most recent resurfacing of this track. It gave the name of the company that landed that contract and did the work. They resurfaced the track, and painted new lane stripes and multicolor indicators and stenciled notes on the track indicating where major metric events start and finish. They probably can not do all that without solid documentation. Maybe they'll share...

Meanwhile I followed Pete's suggestion and made a "virtual measure" via Google earth. That's a good exercise. My virtual tape did not need to be temperature adjusted, but I have no assurance my terminus points were placed exactly where I'd place them in real life. But the result was pleasing: 399.99 meters. By golly, this IS a 400 meter track.

Its not so big an issue now, but a few decades ago a big question we always had when running or working out on a strange track was: Is it 440 yards or 400 meters? I trust that our methodology can answer that question definitively. So, I believe our track measuring work does have some bona-fide value!

JJ

1. We are not in the business of Certifying tracks - Period.

2.There is no short course prevention factor when surveyors measure a track. For IAAF Certification a track can be anywhere from 400.00 to 400.04m long.

3. Every top international measurer I know will use the standard bike method when a segment of the course (start and or finish) is on the track. I don't have a problem with using track measurements instead of the bike method if there is good documentation for the track especially if there are loops involved. It's a toss up if we should be using the SCPF. The addition would be minor. A properly measured track is a great deal more accurate then anything we can do. Also remember that some tracks are measured to have a curb. The running line on a curbed track is 30 cm out and only 20cm out for non curbed track

Bob,

Tried the link you gave for track measurement and it did not work for me.

The Liberty Bell Track at Science Hill High School in Johnson City has a removable rail on the inside of Lane 1. During track season it is on...some of the time. I have not put a micrometer on the lane widths but if I did, what should I expect to see if Lane 1 was designed for 30 cm and all the other for 20 cm?

Oscar

Oscar, Bob has pointed us to a fabulous information source. But the link is tricky. Try going here:

http://www.iaaf.org/about-iaaf/documents/technical

Take a look at the Facilities Manual.

JJ

I like page 4 of the Facility Manual

Oscar,

On a previous discussion on this topic, David Katz reminded us of a very simple way to answer your question: check the stagger between lanes 1 and 2, compare that to the stagger between lanes 2 and 3. If the track is designed for a rail these will be different (1 to 2 stagger will be less); if not, all staggers will be the same.

Took my wheel to Liberty Bell Track and sure enough the Lane 1-2 400 m offset was 5.99 m and the 2-3 was 6.46 m and after that, each successive offset was about .15 m less which I finally realized was because the only lane that goes all the way around to make 400 m is lane 1. I had measured that 20 years ago and it never made sense till now. Thanks, Bob!

So am I correct that if Lane 1 is 400 m at 30 cm in, then pi D means it is significantly less at the outer edge of the inner most stripe?
400 - (30 cm * 2 * 3.1416) = 398.115 meters.