I am new to measuring and now realizing how rounding to soon can greatly impact course length. Where on the RRTC can I find the official legths of 5k,10k, etc. For example, some say a 5k= 3.106856mi and others say 3.10686mi. How many decimals is proper or is there and official list of distances.
Original Post

The conversion between metric and English units is easy to remember.

One inch equals 2.54 centimeters exactly.

By calculation you can make up your own conversion tables to however many decimal places you wish.

For example,
5km x 1000 = 5000m
5000m x 100 - 500000cm
500000cm /2.54 = 196850.39 inches
196850.39 inches = 16404.20 feet
16404.20 /5280 = 3.106856 miles

Put your computer to work using 1 inch = 2.54 cm. It works.

I work with at least 6 significant figures, and only round off the final answer. You are right - intermediate rounding is a bad idea.

Here it is worked out:

Last edited by peteriegel
Thanks Pete, I had created me a table, however i wasn't sure how many significant figures to use. I was rounded each step so my numbers never matched. I just wanted to cross check with the RRTC official lengthS.
Another thing: if the course distance is metric, work all metric until the end, exc. for mile splits. Hell, if the course is Imperial (miles), use 1609.344m to figure it out. As a Vice Chair I HATE getting a marathon listed as 26.2xxx miles. That's NOT the official distance, just some American bastardization of same. Ditto for half marathons.
I'm in full agreement with Jim here.

When I calculate my constant, it's in counts per meter.

And as a certifier, it bothers me to get a distance listed in miles to as many decimal places as the calculator will produce. It's a metric distance. Use metric units.
Thanks for all the input as a newbie I greatly appreciate any advice.
Tommy Scalf
I also calculate a metric constant while figuring, thanks to the frequent encouragement of Bob Baumel. He converted me. If it was not for the desire for mile splits everything would be so much easier technically, although the work would increase because there are more kilometers than miles in a given race.
I have tried to convince race directors to use kilometers, even though it's a little more work for a measurer. Once in a while I succeed and they go for kilometers, but guess what usually happens the next year? You got it, they request mile marks because that's what the runners complained about. Where I've had better luck is with hardcore runners, like DCRRC, who understand that with kilometer splits they get helpful information a little more often.
If anyone can think of a good strategy to address this I am all ears.
Educating the RDs will be a real challenge. I recently measured a 10 km called "Green 6.2" with mile splits of course. But then I also remeasured another 10 km and added km splits. The race committee decided not to bit the bullet and set out both mile and km splits.
Thanks to Bob Baumel, almost all the race courses in Oklahoma are done with kilometer splits only. For the marathon/half-marathon, the measurers usually provide mile splits and 5km splits.
The kilometer splits instead mile splits have been done for so long, the runners are use to it. I don't recall hearing any negative feedback.
It would be interesting to hear from Bob on the issues/problems/feedback as Oklahoma converted from mile splits to km splits !!
Last edited by kenhardwick
Honestly, if we as measurers only marked km, the runners would slowly integrate to it. I think we just go ahead and mark by miles because we are used to it as well. Maybe we should tell the directors we mark by the km system it is extra to re-calc and mark in miles. I bet they would welcome the metric system then. LOL
You know it's not a bad idea to only use metric splits on our maps. I feel the runners would then see the advantages for getting even splits for their race.
At some point we need to acknowledge that this is a service activity and that unless the course is ours, we need to be doing that which is "optional" (such as marking intermediate splits) the way the course "owner" wants them done.

Personally I don't see why we mark miles in a 5K. By the time you get to the mile mark, if you're not on your pace, you're probably not going to be. I can also remember running a 15K many years ago with the goal of finishing in less than an hour. It's a lot easier to remember 4 minutes a km then do the math to add 6:26 miles.

One last note: the organizers of the Bank of America Chicago Marathon have asked for the last few years that all of the intermediate mile and kilometer splits be marked and documented. when you add the halfway point and the one mile to go mark, that's SEVENTY intermediate splits.
With the 2012 Trials coming to Houston, does anyone recall how the splits were handled at New York and Boston in 2008? Any set of splits could be problem on a criterium type course.
Tom,

David Katz did NY and Ray Nelson did Boston. You could check with them.
The last men’s and women’s trials courses were both multiple-loop (criterium) courses.

The men’s course, in New York’s Central Park, was certified as NY07004DK. You can get a map online.

The women’s course, In central Boston, was certified as MA07005 RN. Map is also available online.

Both courses have all the miles marked, and also the 5 km points and the half-marathon.

The London Marathon is also marked this way. The next Olympic marathon, to be held in London, will be four loops, and I don’t know what splits will be used.

All of the courses I’ve seen in non-English-speaking countries have only the kilometers marked, and sometimes the Half.
Pete described the splits for the Boston OT course accurately. The course was designed so the bulk of the course consisted of 4 loops of exactly 6-miles each. For example, mile markers 3, 9, 15, 21 shared the same point. That made it easy for the US press to report on the race progress. -- Justin
I'll take credit for that idea

It just happened to work out that the loop was close to 6 miles, so by moving the turnaround points could be made exact.

In NY, the loop in Central Park was fixed, and while it was close to 5 miles was not exact, so the splits were off from one another by several meters. I believe the organizers just used one clock at each set, and moved it down the road after the runners passed by. A similar situation occurred in St. Louis in 2004. In Helsinki 2005 the World Championships course used a loop that was exactly 10 km. Hugh Jones measured that course.

I think you'd have to be damn lucky to have a fixed loop come out to an even metric or Imperial distance, though.
Last edited by jimgerweck
Thanks for all the input. The Trials Committee will be trying for the same sort of loop. No preliminary measurements yet but one of the sites they have in mind appears to be ~ 9 km.
too bad it can't be "stretched" to 10 km or even 6 miles.

One thing I hope they DON'T do is run the men & women at the same time - each will get shortchanged in media coverage that way.
I know this thread veered off topic but just coming back to "Official Distance", I've just reviewed an application for a 10 nautical miler. All the splits are nautical miles. A nautical mile is exactly 1852 m (about 6076 feet). I certified this 10 nautical miler at 18.52 km. It's interesting to note that the official length of a nautical mile is expressed in meters and not feet.
Matthew, do you know how the distance for a nautical mile was derived?
One nautical mile is one minute of longitude at the equator.

This, of course, has been defined against other more recent standards, as we came to know the sizes of things a bit more accurately, but centuries ago it was a rational definition, understood by those who worked the seas.
Last edited by peteriegel
Not really - even our "Imperial" distances are defined metrically. If we'd just get in line w/ the rest of the world, things would be so much simpler.