Gene J. from Toronto, Canada has a question that is important to every runner out there: As a runner near near the front of the field, I was a bit confused with cones that were laid out along parts of the course and how the course was measured. The cones were placed close to the right side of the road. Was this meant to keep us runners inside to the right of the cones at all times and is that how the course was measured? It was especially confusing as we rounded corners and turns as most courses are measured to the tangents (i.e. straight line being the shortest distance). There was also single and double lines in many sections of the road. I was unsure whether I could cross the centre lines. I did not cross the lines but did see many others crossing the lines on my way back on the second loop.
My Garmin also gave me a measurement of 42:54km. I know Garmins are inaccurate but a 354metre overage is more than I’ve been out for most of the other marathons I have run which makes me wonder about how the course was measured. I am just curious for my own interest but this might be interesting to others.
First, even though you are from Canada, national certification bodies follow the IAAF rules and so the USATF will have a similar process and rules to Canada’s governing body. USATF rules are very explicit.
Next, be very clear that not all courses are certified (though without much doubt your marathon is). This is a very prescribed process and requires a certified official. There are fees involved and so many lower keyed races never do get their courses certified. Your local 5k or 10k course may have been measured by a driven vehicle, traversed by someone with a GPS or mapped out online. In any case, these are not certified and may be wildly inaccurate. Thus, when someone bemoans poor times or oozes over excessively fast times… I first question the course. On the other hand, if it is certified it will have been assigned an official certification registration number. By the way, if the course needs to change due to road construction or whatever (from one year to another), it must be reassessed for recertification.
If you visit this link you clearly see that all CERTIFIED courses follow the absolute shortest possible route a runner could take. Any other route yields a longer course or gets someone disqualified for cutting a course. Generally a road race does not allow running on the sidewalks (though I have yet to see this enforced) so all measurements are roadway measurements. The tangents to corners are within the street and not over the side walks. What this means is that almost every runner runs longer than the actual race distance. And that distance will vary depending on how far out you are pushed by the crowds or how you follow the leaders versus the shortest tangent route on the course. Even elite runners do not run exactly the shortest distance. In some marathons they have a blue line painted on the pavement the whole way. You can see on TV how they do not always follow this. And every step not on that line, is longer than the certified course.
So, to your questions.
The cones are usually used to denote where you cannot cross a mid-line stripe on a roadway. Often you will see these on out-and-back courses. Ones solely on one side would indicate to me NOT to run “outside” them. It appears from your recount that you ran correctly.
Your GPS is most likely as accurate as it ever was. Within the usual margin of error (which also in my experience would never be as far off as your numbers) these are very accurate. You added over the course of the marathon extra distance with every side-of-street switch, every go-around-that-person-pass, and every weave-over-to-the-water-stop move, etc. So, what do I say? You ran much further than you had to because you did not follow the shortest route. The good news is that using your final official time and your actual distance, you ran a faster pace per mile than you thought.