Measuring a marathon

Is the RD expecting to have the same start and finish for the two races?

First, two different calibration course are ok. However, why not setup a cal course close to the race as you may have to make an adjustment after the post cal.

I suggest you measure from the start to the finish of the half. Then compare the two rides and use the shorter for this certified distance. Calibrate the bikes and make an adjustment if necessary.

Now for the marathon - If the races have a common finish, measure from the finish of the half, 1/2 of 21.0975km for the marathon turn. Again, compare your rides and use the shorter. Calibrate the bikes and make an adjustment at the turn.

Mile marks or km marks can be done by both riders or each can do one.

Mark yes the same start and the same finish line for both races.

J. A.,
Don't take this job if they really do insist on co-located start/finish with no out-and-back section to accomplish the co-location. It is virtually impossible to do this.

I went through this with the Manchester (NH) Marathon & Half-Marathon and after cruising many roads and routes throughout a hot summer, I couldn't get the two start lines closer than 16 feet apart. At that point, I told the RD to start them both at the longer of the two starts, if they really needed to have them start together.

However, if you do take this job, set an hourly rate and make it a career.

If the two courses are relatively short, like a 5k and 10k, you can do a lot of measuring online in order to find routes that will have the same start and finish lines and be close to the correct distances (if you're lucky). But with a marathon/half the online measurements are not accurate enough to get you close enough.

I would measure the half from the finish back to the start because it sounds like the start is where you have flexibility. Then I would measure the marathon from the turn-off point (you have recorded the turn-off point distance during the half measurement) to the finish following whatever course you have found most likely to be close enough.

That's all I would try to do in one day. I would return home and start measuring adjustments to the marathon online to try to find a course that will end up close. Since you are measuring only adjustments, the online measurements should be able to get you pretty close. Of course, in the end you need to return to the course and measure the adjustment for real. Like Ron says, trying to figure out an adjustment by measuring on-site will take forever, and there is no way I would do it.

Before I did any of this though, I would have a long talk with the RD so he understands this is not an easy task, and it will be priced accordingly. And also that when you are finished, the distance on the certificate will read something like 43.213km, not 42.195km.

J.A.,
Ron is right on that-- the likelihood of getting both start and finish in the same place AND having no turnaround on the course is next to zero.

This may be a case where you have to educate the RD and nudge things in the right direction. I would start with some online measurement as Mark suggests. How much discrepancy do you get with the course they've suggested-- are there some good alternatives, etc. Sometimes you can't measure the whole thing online, there may be places you just can't see from aerial imagery that's available. But if you're lucky you can at least know a little bit of what you might find when you measure.

Depending on how much flexibility you'll have on start and finish, you might end up needing two turnaround points, one for the half and one for the marathon. But with luck you may only need one for the marathon. That's better because, presumably, the marathon is moving at a slightly slower pace and a turnaround is correspondingly less of a pain for the runners.

One idea for convincing the RD to go with a turnaround: if you have any possible turnaround area where there is a wide street, you can lay out a semicircular turnaround with a large enough radius that the runners will hardly have to slow down. (First measure for a point turnaround and then you can redesign for a smooth turnaround; some of us have done that a lot and can help with the math of that if you need).

Don't expect to complete this in one day, it is a major undertaking. Perhaps the first day you will just collect all the information you need to plan your next steps.

Gene's suggestion is good-- if you lay out a handy cal course it will make a world of difference as you proceed.

Question, do they want all of the kilometers or just the multiples of 5 (which is more common)?

On the question of one marking kilometers and one marking miles, I wouldn't suggest it-- do whatever you do together so that the two of you can compare measurements. I wouldn't even mark miles or kms on the first measurement, but be sure both of you stop at the same points (or use that neat Guido Brothers trick). You can stop and take readings at arbitrary points along the way.

J.A.,
When I measured the Manchester courses, the RD needed the finish lines at a specific location, so I first measured the half, finish to start.

Like your situation, the two courses followed the same route up to about 12.9 miles. The first half was easy. Measuring backwards, I made a mark where the two courses diverged and recorded my distance, and finished the half measurement. Then I went back and measured from that point forward around the remainder of the marathon course as laid out by the RD. Of course, the two start lines were at different places. I then measured the difference between the two starts and went looking for an adjustment to compensate for the difference.

Fortunately (I think), my day job was in Manchester. Each night, I'd go online to plot a potential adjustment, then after work the following day, I'd calibrate my bicycle and check the change. Without exageration, this went on for well over a month. When I got to 16 ft apart, I called it quits.

Be sure to set your fee realistically. You'll be doing this for awhile.

Ron

J.A.,I recently encountered a similar situation. Fortunately, the courses are only 5K and 10K. It took me nearly 30 minutes to convince the organizers that having the start and finish of both races contiguous requires an out-and-back section for one of the courses (logically, the 10K).

As has been suggested, you may be wading into rough waters with this, depending on how savvy your client is. Ron says "set your fee realistically". I would be inclined to set an hourly rate and then provide an estimate of hours, with some upper limit that is agreeable to all. To take into account the fact that the time could go beyond the limit you set, I recommend you have the client sign a brief agreement that says something like: "Hourly rate: X; Estimated hours: hours will be billed as required by the scope of work up to a maximum of Y; any requirement for hours beyond Y will be negotiated via conversation with the client at the time that Y is reached." I do this for the course design and permitting work that I do.

Mark suggests that you may be able to get "close enough for jazz" to have the two contiguous S/F locations by using on line imagery measurements, and he concludes that this may be difficult. I would say "next to impossible" unless you get very lucky with the configuration of the streets that can be permitted for the event. I prefer Bob Thurston's example of a wide turn in the out-and-back section. You could do the math to calculate the turn, or you could just measure to a point and map out an arc around the turn without adding much difference, or you could simply paint an arc on the pavement, measure it from fixed objects every few yards, record these points, and call it a day. Anything else could drive you around the bend trying to do what non-measurers have a hard time grasping the difficulty of, IMO.

Hi Ron,
I see you said you got to 16 feet but you do not say whether it was for the marathon or for the half that was 16 feet off. The reason I am wondering is because I looked at the certificate for both the half and the marathon and they both show the correct km listing but if one was 16' off the km distance would be different than what is on the certificate or am I missing something?
I think we maybe going thru a high school parking lot as a last resort where we can control the distance somewhat and have a water stop and maybe put a band.

J. A.,
I just went back to my maps and the difference was actually about 18 feet.

Anyway, I didn't make any adjustment to either course. I created separate start lines, one for the marathon and the other for the half, just as the courses were measured.

When the race director insisted that both races had to start together, I simply told her to use the start line for the marathon, which resulted in the runners in the half running an extra 18 feet.

Ron

I measured a marathon and half marathon here in the UK with start and finish lines the same for both races.I spent ages trying to get the two races the same,but in the end had to settle for the marathon being about 30 ft over. One of my club mates ran 3:00.01 .I didn't have the heart to tell him that he probably had got sub 3 after all.

Pity!